Animal Physiology

The discipline of beast physiology is underpinned by the concept of homeostasis of the intra- and extracellular environments, neural and endocrine systems for homeostatic regulation, and the various physiological systems including ionic and osmotic balance, excretion, respiration, circulation, metabolism, digestion, and temperature.

From: Encyclopedia of Environmental , 2008

Animate being Physiology

C.E. Cooper , P.C. Withers , in Encyclopedia of Ecology (Second Edition), 2008

Animal Physiology

Animal physiology is the study of how animals piece of work, and investigates the biological processes that occur for brute life to exist. These processes tin be studied at diverse levels of system from membranes through to organelles, cells, organs, organ systems, and to the whole creature. Animal physiology examines how biological processes function, how they operate under various ecology weather, and how these processes are regulated and integrated. The study of animal physiology is closely linked with anatomy (i.due east., the relationship of function with construction) and with the basic concrete and chemical laws that constrain living too as nonliving systems. Although all animals must function inside basic concrete and chemical constraints, in that location is a variety of mechanisms and processes by which different animals work. A comparative approach to brute physiology highlights underlying principles, and reveals diverse solutions to diverse environmental challenges. It tin can reveal similar solutions to a common trouble, or modifications of a particular physiological system to part under diverse weather. The discipline of fauna physiology is diverse and hither the major areas of research and investigation are outlined.

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TROPICAL SOILS | Boiling Tropical☆

S.W. Buol , in Reference Module in Earth Systems and Environmental Sciences, 2013

Chemical and Mineralogical Composition of Soils

Of the chemical elements essential for plant and animal physiology, only carbon, oxygen, and hydrogen, are derived direct from air and water. Nitrogen and to some extent sulfur are derived from the air only must be present as inorganic ions in the soil before they can be utilize by plants. The other essential elements are obtained from the dissolution of minerals in the soil. Essential element bearing minerals are derived from the geologic cloth within which the soil is formed. An inadequate supply of any essential element limits institute growth. The most frequent limitations result from insufficient plant-available nitrogen, phosphorus, potassium, calcium, or magnesium.

Practically no nitrogen is present in soil minerals. Nitrogen enters the soil as ammonium and nitrate dissolved in rainwater or via fixation from the air past nitrogen-fixing microbes in the soil. Some nitrogen-fixing microbes in the soil are symbiotic and the nitrogen they excerpt from the air is incorporated into their legume plant host. Other nitrogen-fixing microbes are non symbiotic, and the nitrogen they extract from the air is incorporated into their cells. Nitrogen is besides present in the organic residues of dead organisms in and on the surface layers of soil. Plants practise not ingest the organic forms of nitrogen simply as microbes in the soil decompose organic residues and exhaust carbon dioxide to the air inorganic forms of nitrogen are released into the soil solution and become available to growing plants, leach into the groundwater during periods of excessive rainfall, or render to the air as nitrogen gas during periods when the soil is saturated with water. Constitute-bachelor nitrogen contents in soil are transient and closely related to the nitrogen content in the organic residue and the rate at which the residue is decomposing.

Phosphorus is nowadays in merely a few minerals in the soil. Apatite, a soluble calcium phosphate mineral capable of supplying establish-available phosphorus, is the most common source of phosphorus and most arable in soil formed in limestone. Iron and aluminum phosphate minerals are extremely insoluble and do non release phosphorus rapidly enough for rapid plant growth. Soils with loftier atomic number 26 and aluminum contents tend to blot phosphate applied every bit fertilizer and decrease its availability to plants. This is a serious trouble in attempts to fertilize food crops in many soils in the tropics.

Potassium is nowadays in mica and feldspar minerals. These minerals are rather easily decomposed in the soil environment and consequently are sparse in soils formed in siliceous materials and sediments that have been repeatedly transported and deposited on the land surface.

Calcium and magnesium are most abundant in carbonate minerals associated with limestone and some carbonate rich sandstone. Carbonate minerals are likewise relatively unstable when subjected to weathering and therefore most abundant in soils formed directly from limestone, some sandstone, and recently deposited sediments derived from carbonate rich rock.

Soil pH is a measure out of the acidity or alkalinity of h2o in the soil and has a direct effect on how rapidly many of the essential elements are available to growing plants. In the absence of carbonate minerals, most soils in the boiling tropics are acrid in reaction and simply limited quantities of essential elements present in the soil are available for establish growth. Acrid soils with pH values less than approximately 5.two also accept a concentration of aluminum ions that is toxic to most, merely not all ingather plants. Additions of lime (finely ground calcium and calcium:magnesium carbonates) are desirable and often necessary to reduce or eliminate aluminum toxicity, heighten the pH of the soil, and increment the availability of the essential elements to most crop plants growing in acid soils.

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TROPICAL SOILS | Humid Tropical

S.W. Buol , in Encyclopedia of Soils in the Environment, 2005

Chemical and Mineralogical Composition of Soils

Of the chemical elements needed for plant and animal physiology, only carbon, oxygen, hydrogen, nitrogen, and to some extent sulfur are derived from air and water. The other essential elements are obtained from the minerals in the soil. Mineralogical properties of soils are derived from the geologic fabric within which the soil is formed. An inadequate supply of whatever essential element limits institute growth. The most frequent limitations issue from insufficient institute-bachelor nitrogen, phosphorus, potassium, calcium, or magnesium.

Practically no nitrogen is present in soil minerals. Nitrogen enters the soil as ammonium and nitrate dissolved in rainwater or via fixation from the air by nitrogen-fixing microbes. Some nitrogen-fixing microbes in the soil are symbiotic and the nitrogen they extract from the air is incorporated into their legume plant host. Other nitrogen-fixing microbes are not symbiotic, and the nitrogen they extract from the air is incorporated into their cells. Nitrogen is full-bodied in organic residues in the surface layers of soil. As organic residues decompose, inorganic forms of nitrogen are released into the soil solution and become available to growing plants, leach into the groundwater during periods of excessive rainfall, or render to the air as nitrogen gas during periods when the soil is saturated with water. Plant-available nitrogen contents in soil are transient and closely related to supplies of organic residue.

Phosphorus is nowadays in merely a few minerals. Fe and aluminum phosphates are extremely insoluble and exercise not release phosphorus apace enough for rapid institute growth. The release rate is so wearisome that soils with loftier iron and aluminum contents tend to absorb phosphate applied equally fertilizer and decrease its availability to plants. Apatite, a more soluble calcium phosphate mineral capable of supplying plant-available phosphorus, is a common source of phosphorus and often present in limestone.

Potassium is nowadays in mica and feldspar minerals. These minerals are rather hands decomposed in the soil environment and consequently are seldom nowadays in materials that have been repeatedly transported and deposited on the land surface.

Calcium and magnesium are nigh arable in carbonate minerals associated with limestone and some sandstone. Carbonate minerals are also relatively unstable when subjected to weathering and therefore are present only in recent geologic sediments, limestone and some sandstone.

Soil pH is a measure of the acidity or alkalinity of water in the soil and has a directly result on how rapidly many of the essential elements are available to growing plants. In the absence of carbonate minerals, soils in the humid tropics are acid in reaction and only limited quantities of essential elements present in the soil are available for plant growth. Acrid soils with pH values less than approximately 5.2 likewise have a concentration of aluminum ions that is toxic to some but non all crop plants. Additions of lime (finely ground calcium and calcium:magnesium carbonates) are desirable and often necessary to reduce or eliminate aluminum toxicity and increase the availability of the essential elements to virtually crop plants growing in acid soils.

The rate at which essential elements in the soil are bachelor to plants is disquisitional to understanding soil fertility. Plants extract the elements they need from the soil as inorganic ions in the soil solution. The amount of each essential element in the soil that is bachelor to plants changes rapidly every bit the moisture content of the soil changes and also depends on the rate at which organic compounds decompose to release organically bound elements equally available inorganic ions. Less than approximately i% of the total amount of about essential elements in the soil is present in an bachelor form. Plant species differ greatly in the rate at which they need to acquire essential elements for acceptable growth. The rate at which nutrients go available influences natural plant communities and is directly related to human food production. Nearly human food crops require ninety–120   days to mature. Food crops must have a charge per unit of nutrient availability many times faster than required by native ecosystems. A high-yielding grain ingather of rice, wheat, or corn must acquire approximately as much phosphorus in xc   days as trees acquire from the same area of country in more than than 20   years. In addition, tree roots usually penetrate more than securely and exploit a larger volume of soil than food crops. Therefore, the concentration of available nutrient elements virtually the soil surface must be considerably greater to supply adequately the needs of a nutrient ingather than to back up tree growth.

Humans harvest and ship their food crops to a domicile some distance from the site where the crop was grown. Often the seed portion of the establish is consumed and only the less nutrient-rich stems, leaves, and roots of the crop institute are returned to the soil equally organic residue. Considerable amounts of organic residues are required to fertilize a crop institute, because these residues decompose slowly to release inorganic ions for crop growth. The common practice of burning residues facilitates rapid crop growth by releasing organically bound nutrients.

Historically humans take populated areas of soil with high levels of mineral fertility. These are unremarkably igneous or volcanic materials of bones mineral composition, sedimentary rocks such as limestone rich in calcium, magnesium, and phosphorus, and contempo inundation plains frequently renewed by depositions of material derived from fertile geologic materials and eroded surface soil. Where the mineral limerick of the soils contains only pocket-size amounts of essential elements and a large corporeality of tiresome-growing natural biomass is present, a system of food production known equally slash and burn is practiced. Although some essential elements are volatilized and lost, fire is the primary method of speedily decomposing organic material and creating a short time menses when nutrients contained are quickly bachelor equally inorganic ions. If in that location is enough biomass, at least i ingather can be successfully grown in the 90   days subsequently burning. If correctly done, burning too assures that the surface temperature of the soil becomes high enough to reduce weed contest by killing most weed seeds near the soil surface. A second and tertiary crop is often possible earlier the bachelor supply of essential elements is exported from the field as human food and the rate of nutrient availability is reduced to a point where crop yields are low and⧸or weeds go a major problem. Later on the farmer abandons that state, a succession of native communities that are able to grow with lower rates of nutrient menstruation from the soil invade the site. After some years, the tiresome-growing native vegetation acquires enough nutrients in its biomass that it tin can again be cut, stale, and burned to obtain a site for another cursory sequence of crop plants. This method of nutrient-availability management has numerous variations amongst different ethnic cultures. Only low human population densities are sustained past slash-and-burn down agriculture because of the long periods of fourth dimension (usually between 10 and thirty   years and inversely related to the mineral fertility of the soil) that must be allowed for natural vegetation to accrue sufficient quantities of essential elements needed to fertilize a nutrient crop after burning. Where domestic animals are allowed to graze large areas of native vegetation, essential elements full-bodied in their excrements are ofttimes nerveless and used to fertilize modest areas of nutrient crops. In areas where infrastructure enables crops to exist exported and essential nutrients imported equally concentrated fertilizer, continuous nutrient-ingather production is good on fifty-fifty the most chemically infertile soils. Many combinations and variations of these strategies presently be throughout the humid torrid zone.

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Impacts of Ocean Acidification on Arctic Marine Ecosystems

Scott Elias , in Threats to the Arctic, 2021

Function of pH in animal physiology

pH too plays a vital office in many aspects of animal physiology. The pH of actual fluids and organs is critical to the physiology of organisms ranging from one-celled plankton to fish. Metabolic processes are closely linked to pH, and when pH falls outside the normal biochemical boundaries, these physiological systems can be overwhelmed (Gattsuo, 2015). In other words, a decrease in marine water pH changes the concentration of biomolecules that are key to animals' physiology. Wittmann and Pörtner (2013) identified the variability of the effects of ocean acidification among the different kinds of marine animals (Table 5.1 and Fig. five.14) . Phyto- and zooplankton, echinoderms, mollusks, crustaceans, and fish all have unlike responses to acidification. Crustaceans announced to suffer the least impacts because their exoskeletons are a mixture of biologically synthesized material (chitin) and calcium carbonate. Equally discussed in the following, fish practice not build calcium carbonate shells, but they must maintain suitable pH levels in their soft tissues, to enable the chemical reactions that sustain life and facilitate reproduction.

Fig. 5.14. Sensitivities of animal taxa to ocean acidification. Fractions (%) of coral, echinoderm, mollusk, crustacean and fish species exhibiting negative (red bars), neutral (yellow bars), or positive (green bars) furnishings on functioning indicators reflecting individual fitness in response to the respective levels of atmospheric CO2 levels (expressed as the partial pressure of COtwo in sea waters).

 After Wittmann, A.C., Pörtner, H.O., 2013. Sensitivities of extant animal taxa to ocean acidification. Nature Climate Change 3(xi), 995–1001. https://doi.org/10.1038/nclimate1982.

Gattuso et al. (2011) reckon that increasing ocean acerbity will take a negative and pregnant affect on calcifying algae, coccolithophores, and mollusks. Increased acerbity may take a positive upshot on crustaceans and convey a slight advantage to some echinoderms (for case, starfish, sea urchins, sand dollars, and ocean cucumbers). Some organisms may have the innate ability to boost their metabolism and calcification abilities to compensate for lower calcite saturation levels. These assessments more often than not hold with those of Kroeker et al. (2010), who described negative effects on survival, calcification, growth, and reproduction of most calcifiers. Nevertheless, they also discussed the significant variation in the sensitivity of marine organisms to increasing ocean water acidity. They found that calcifiers that eolith one of the more than soluble forms of calcium carbonate (Mg-calcite) can be more than resilient to ocean acidification than those that deposit the less soluble forms of calcite and aragonite. The life histories of these organisms play a role in calcifier response to acidification. Kroeker et al. (2010) discussed variations in the sensitivities of the different developmental stages of these organisms. This is another aspect that varies between taxonomic groups. Overall, their analyses suggest that the biological effects of ocean acidification are generally large and negative. Even so, the variation in sensitivity between different groups of organisms will have important implications for the response of marine ecosystems to increasing acidification.

Moreover, responses of planktonic taxa to ocean acidification terminate up having consequences for organisms college upwards the food concatenation. Elevated CO2 levels have been shown to modify the biochemical composition of phytoplankton species. These changes lead directly to modifications in the productivity and nutritional value of zooplankton. These responses are in addition to the negative effects that have been observed in critical zooplankton species that serve every bit the forage base for early on life stages of larger-bodied marine fishes. These indirect food web-mediated impacts take the greatest effect on fish larvae because they have limited energy reserves and are highly sensitive to their foraging surround during early life stages (Hurst et al., 2019).

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Electronic Tagging and Tracking of Animals in Inland Waters☆

Steven J. Cooke , ... Jason D. Thiem , in Reference Module in Earth Systems and Ecology Sciences, 2022

Biologgers

Biologgers are sensors that are attached to or implanted inside of animals to collect information about their environment (eastward.chiliad., spatial position, temperature), and/or the animal's physiology (eastward.g., center rate), or behavior (eastward.1000., running, swimming, feeding), and shop the information in memory on the device (Rutz and Hays, 2009). This storage facilitates continuous and high-frequency drove of the information derived from a diversity of sensors (eastward.k., dispatch, heart charge per unit, magnetometer, temperature, dissolved oxygen, water speed, global position at up to hundreds of samples per 2nd). These capabilities have enabled biologgers to exist applied to diverse questions about a wide range of species inhabiting inland waters. For case, loggers containing varied combinations of dispatch, heart rate, temperature, and water depth sensors have been used to rail the behavior and survival of fishes and turtles afterward exposure to stressors such as fisheries interactions (Algera et al., 2017; Gutowsky et al., 2017; Prystay et al., 2017; Lennox et al., 2018), besides as the metabolic costs of fish spawning behaviors (Clark et al., 2010; Prystay et al., 2019). Tri-axial accelerometers, which mensurate dispatch as a proxy for movement in three directions, can exist used to remotely measure very fine calibration behaviors, such as air breathing at the h2o surface past arapaima (Arapaima cf. arapaima; Lennox et al., 2018). 1 especially exciting application of biologgers is in remotely estimating beast bioenergetics (Cooke et al., 2016b), which requires calibration between oxygen consumption and sensor output (due east.g., heart rate or acceleration) with laboratory equipment (Clark et al., 2010) prior to deployment on wild animals.

Although biologgers enable continuous measurement at great resolution, the need to recover the device back from the tagged fauna limits applications in inland waters to situations that permit for retrieval, which are often short-term studies within a constrained expanse. In semi-aquatic animals such every bit diving birds, biologgers including GPS, acceleration, and depth sensors are commonly used to appraise motility patterns, foraging behaviors, and locations (Ropert-Coudert et al., 2009). In a more than extensive written report on fish, Raby et al. (2018) used temperature loggers to rail thermal experience of walleye (Sander vitreus) over multiple years to understand how temperature influences motility patterns in Lake Erie, North America, with device retrieval facilitated primarily past large scale fisheries. To overcome challenges with device retrieval, biologger tag packages with timed pop-off devices tin enable retrieval, although these packages are large and constrained in application to relatively large animals due to issues with tag burden (Broell et al., 2016).

The continuous, fine scale information that biologgers provide on beast behavior, physiology, and proximal environmental weather condition makes them an of import tool for understanding how ecology weather condition bear on individuals, which is used to scale to populations and unabridged inland water ecosystems. Standing advancements in device sensor capacity, miniaturization, and retrieval mechanisms (Boyd et al., 2004; Block, 2005; Rutz and Hays, 2009), as well as integrating of other ecology measures and telemetry applied science will be essential to understanding and mitigating the impacts of rapid environmental changes on biodiversity, ecosystem integrity and services provide by inland waters (Cooke, 2008; Cooke et al., 2012; Bograd et al., 2010).

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Exposure of Humans to Fluorine and Its Assessment

Maja Ponikvar , in Fluorine and Health, 2008

iii ESSENTIALITY OF FLUORIDE

Many elements occur in living organisms in such modest amounts that early researchers were unable to notice their presence or measure their precise amounts. Involvement in trace elements in human and animal physiology began over a century ago with the development and advances in technology that immune detection and measurement of traces of a number of metal‐containing compounds that were non previously suspected to be of biological significance. During the 1930s, a wide range of nutritional disorders of humans and farm stocks were establish to be acquired past either deficiency or excessive intake of trace elements from the natural environment. In 1931, three research teams independently recognized that fluoride in water consumed during infancy and early on childhood resulted in mottling of tooth enamel [ 33–35].

The criteria for identifying nutritionally essential trace elements accept evolved extensively over the past l years and may exist expected to expand as the outcome of time to come research. The definition of elements as essential is thus difficult and, depending on the definition of essentiality, not unanimous. Iyengar et al. [36], in 1978, considered an element to be essential if (1) the organism can neither grow nor complete its life wheel if the element is not available in sufficient quantity, (2) the element cannot be wholly substituted by another element and (3) the element has a direct influence on the organism and is involved in its metabolism. Based on this definition, fluorine is non an essential element. Later on, in 1987, Underwood and Mertz [37] established essentiality as being when a reduction of the element beneath the range of tolerable levels, better termed 'range of safe and adequate intake', results in a consistent and reproducible impairment of a physiological function. On this basis, fluorine was included in the list of essential elements considering of its proven benefits for dental health and its suggested role in maintaining the integrity of bones.

The onetime prototype that dominated nutrition inquiry of the past was dissection. The complex health effects of whole diets were amenable to scientific study just past separating foods into their components, which could be measured and their furnishings investigated individually. The gradual emergence of 'new' paradigms and their influence on diet enquiry increased to the point where they began to modify the sometime paradigm. 'New', emerging paradigms were addressed by Mertz [38] in 1993: (1) the concern with individual nutrients (dissection) is being complemented past a business organisation for balanced interactions inside the whole diet (synthesis); (2) the sectionalization of the elements into essential and toxic categories is slowly existence replaced by the concept of the full dose–response curve and (3) the dominating part of the concept of deficiency in determining nutritional requirements is gradually beingness complemented by a business organisation for the total wellness effects of elements. In accordance with these paradigms, the Expert Consultation of the WHO, Nutrient and Agricultural Organization and International Atomic Energy Agency [39] accepted in 1996 a revised definition of essentiality that says: 'An element is considered essential to an organism when reduction of its exposure below a certain limit results consistently in reduction in a physiologically important part, or when the chemical element is an integral part of an organic structure performing a vital office in that organism'. This definition is not absolute; it depends on what is considered to constitute a 'physiologically important function', 'consequent' functional impairment, etc. Caries is not a consequence of fluoride deficiency; however, since the Expert Consultation considered resistance to dental caries to exist a physiologically important function, the element fluorine was regarded as essential. Fluorine was, at the same time, classified into the grouping of potentially toxic elements, some of which may nevertheless accept some essential function at low levels [39].

It has to be recognized that, although fluorine should exist probably regarded as an essential element, there is no prove so far from human studies that overt clinical signs of fluoride deficiency exist. No specifically diagnostic clinical or biochemical parameters have been related to fluoride deficiency [8,39]. It must also be noted that an experimental diet completely free of fluoride, capable of provoking fluoride deficiency, is hard to obtain. Information technology is also difficult to prove that information technology is costless of fluoride, considering of methodological and analytical issues in determining fluorine at low levels.

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GROWTH REGULATION | Hormones in Growth and Development

M. Le Bris , in Encyclopedia of Rose Science, 2003

Introduction

Since the beginning of the twentieth century, the plant hormones, or phytohormones, accept been the subject of more and more than detailed scientific researches. Their listing is constantly increasing and their mechanisms of action are start to be elucidated.

The definition of a hormone in brute physiology is unambiguous. It is an organic chemical compound, active at very low concentrations, synthesized by endocrine glands and excreted in the internal milieu which transports it towards an organ or a tissue sensitive to its action, the part of which is controlled past this hormone. Hence, an animal hormone is considered as a chemical messenger that transmits an order originating from a regulating eye. It thus contributes to the function harmony of the whole organism.

In plants, the hormone concept is much less restrictive concerning the emission, transport and reception of the hormonal signal. There are no endocrine glands but zones of preferential synthesis that are non specifically differentiated. Transport from the synthesizing organ to the sensitive tissue does not always take place. The activation of the synthesis is by and large directly determined by the environment. The specificity of cell response is weaker than in the brute environs. Moreover, a phytohormonal response does not necessarily event from the activity of only i hormone; it results rather from interactions between several substances. The response is a office of the hormone concentration in the target cells. The hormone content of a prison cell results from different mechanisms such as in situ synthesis, import and consign, catabolism, temporary inactivation and storage as conjugated forms. The response to hormones is also determined by the sensitivity of the target cell. Differences in sensitivity depend on genetic, anatomical, physiological and environmental factors as well as interactions with other hormones. Hence a phytohormone can be considered equally an organic, endogenous, oligodynamic substance that carries an information to a sensitive target cell the functioning of which is influenced by this hormone.

In Rosa spp., every bit compared to another institute species, specific cognition concerning the phytohormones is still low. All the same, among higher plants, especially angiosperms, the involvement of the phytohormones in the physiological processes controlling growth and development are very like. Roses are non known to comport fundamentally differently from the majority of angiosperms. Data concerning hormonal response of rose plants derive mainly from horticultural applications such as vegetative propagation, branching and the control of found architecture, and postharvest flower care. In this commodity, the iv classical institute hormones are examined, i.east. auxin, cytokinin, gibberellin and abscisic acid, plus ethylene which is often considered equally a gaseous hormone ( Figure 1 ).

Figure 1. Chemical construction of representatives of different master groups of hormones in plants.

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Computational Toxicology

Southward. Satheesh Anand , Harihara M. Mehendale , in Encyclopedia of Toxicology (Second Edition), 2005

Computational Toxicology in Quantitative Risk Assessment

Following are the areas in which computational toxicology is expected to reduce or eliminate the uncertainties:

Dose–Response Assessment

Figurer-based technologies would assist in determining the shape of the dose–response bend in the low dose range based upon in vivo and in vitro information, and to correlate with depression dose adverse effects. These technologies may besides result in the identification of useful biomarkers, adverse result, and mode of activity of the low dose range.

Cross-Species Extrapolation

Ane of the major challenges in regulatory toxicology is the prediction of toxicity of a chemical beyond the species; soon, the effects in humans are predicted from animal studies. The concept of extrapolation is based on the noesis that all the species ascend from common evolutionary ancestors. However, it is not lilliputian because chemicals vary as a part of an animal'south physiology and its environment and pathways of metabolism tin differ significantly across species, even closely related animals. These can exist addressed past biologically based dose–response models. Although in that location is remarkable similarity in basic biology among animals, in that location are also significant species-specific differences in genes, proteins, biochemistry, and physiology. These differences lead to uncertainties in extrapolation. To address this, characterizing the toxicity pathways is critical.

Chemical Mixtures

Multichemical exposures are ubiquitous. A number of uncertainties exist from the style of activeness, type of interaction to toxic outcome in the mixture risk assessment. Computer-based technologies have huge potential to elucidate the mechanisms and predict the event for existent-world mixtures rather than the defined mixtures at high-dose concentration.

Sensitive Population

There is an increasing concern that some people are more susceptible to toxic effects of one chemical compared to others. This group includes children, meaning women, elderly, genetic background, life-way such as smoking, alcohol consumption, diet, and existing disease conditions. With application of computational toxicology it is expected that we will be able to fine-tune our ability to predict the mechanisms behind the susceptibility and reduce the doubtfulness.

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Microbial bioremediation of Cr(VI)-contaminated soil for sustainable agriculture

Swati Pattnaik , ... Deviprasad Samantaray , in Microbial Biodegradation and Bioremediation (Second Edition), 2022

nineteen.2 Chromium production and toxicity

The 24th element of the periodic table, chromium, extracted from chromite ore, finds a wide assortment of applications in industries exploiting its color, strength, hardness, corrosion resistance, and oxidizing capabilities. Chromite deposits are found in various countries, including the Philippines, Southern Republic of zimbabwe, and Turkey; still, Southward Africa is considered to be the largest producer comprising seventy% of the world's total chromium reserve (Samantaray et al., 2014). Globally, India has established itself equally the third chromium producer, where Sukinda mining surface area, Jajpur, Odisha has 97% of India'due south chromite deposits. All-encompassing mining activities in the Sukinda mining area since more than 4 decades have generated a huge corporeality of revenues. Thus information technology has been listed among the most chromium-contaminated places in the earth (Blacksmith Institute Report, 2007).

Chromium plays a key role in the biological organisation, but beyond a level, it is toxic, mutagenic, carcinogenic, and teratogenic (Balamurugan, Rajaram, & Ramasami, 2004). Moreover, the metals accept exacting consequences on humans such as brain damage, reproductive failures, nervous organization failures, and tumor formation (Devi, Thatheyus, & Ramya, 2012). Chromium and its compounds are widely used in different industrial sectors and then enter into the ecosystem through effluents (Fig. 19.1 ). Cr(III) is less toxic, nonbioleachable which is an essential micronutrient in animal physiology, playing a function in glucose and lipid metabolism. It is involved in peripheral activeness of insulin, normal glucose utilization, stimulation of enzyme systems, and perhaps in the stabilization of nucleic acids ( Samantaray et al., 2014). According to USEPA, permissible limit of Cr(VI) in water is 0.05   mg   L−1. Cr(Vi) is a stiff oxidant that can pass through cell membranes and then be reduced to Cr(III) by various reducing agents like ascorbic acid, sodium sulfite, glutathione, NADPH, and NADH (Petrilli & Flora, 1978). The Cr(III) binds with nucleic acrid and other prison cell components by producing free radicals (Medeiros et al., 2003) leading to cell impairment. A low concentration of chromium has been reported to stimulate plant growth; however, chromium concentration of v–60   mg   kg−1 of soil tin damage plant roots (Pratt, 1966). Cr(6) also affects growth, photosynthesis, morphology, and enzyme activities in algae and is toxic in 20–ten,000 ppb concentrations (Towill, Shriner, & Drury, 1978).

Effigy nineteen.1. Environmental cycling of chromium.

Growth and development of microbes require a very low concentration of chromium, while loftier concentration causes cell elongation, jail cell enlargement, and reduced cell division leading to cell growth inhibition (Pas, Milacic, Drasar, Pollak, & Raspoor, 2004). Usually, chromium concentration in between 0.05 and 5   mg   L−1 is toxic to microbes; however, internal chromium concentration is species dependent (Babich, Schiffienbauer, & Stotzky, 1982). In aqueous system, diatoms are replaced by algae and cyanobacteria, when Cr(VI) concentration increases from 0.1 to 0.4   mg   L−1. In the Escherichia coli strain (NR 9064), loftier concentrations of Cr(Half-dozen) led to the formation of DNA–Deoxyribonucleic acid crosslinks and decreased polymerase activity (Snow, 1994); still, in fungi, Cr(VI) toxicity leads to reduced growth of mycelia (Babich et al., 1982). Cr(Half dozen) concentration at 1   mg   kg−ane of soil reduces/alter soil microbial diversity. It is mutagenic to several microbes such every bit Due east. coli, Bacillus subtilis, and Salmonella typhimurium past frameshift mutation and basepair substitution (Samantaray et al., 2014). Hence, microbial bioremediation of Cr(VI)-contaminated soil is highly essential for sustainable agriculture.

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Cambrian explosion

Nelson R. Cabej , in Epigenetic Mechanisms of the Cambrian Explosion, 2020

Instructive role of the nervous organisation in evolution, transgenerational inheritance and speciation

The nervous system in eumetazoans is responsible for their behavior, physiology, and life history. All of them are inextricably linked to each other and to animal life itself. Physiology studies functions of the organism, merely if "the part is changed structure", the fauna physiology is linked and evolves aslope, and in relation with, animal morphology, for ultimately the function is the raison d'être (reason for existence) of the structure. Herein information technology is demonstrated that, besides the behavior, physiology, and life history, the nervous system is essentially involved in molding the creature structure and organogenesis.

The idea of involvement of the nervous organization in molding metazoan morphology is not new. Three decades agone, B. John and One thousand. Miklos (1988) intuitively pointed out that "At that place is every indication that, not only did the evolution of the nervous arrangement involve a far more significant sequence of events than the morphological systems with which most evolutionists accept been preoccupied, merely, additionally, that its development in plough directed many of the morphological changes that have occurred" (John and Miklos, 1988). But B.K. Brian was the first to detect and emphasize the inductive role of the incipient CNS in the postal service-phylotypic development by giving ascent to a network of inductions cell differentiation, histogenesis and organogenesis (Hall, 1998a; Hall, 1998b). Recently Grand.Due east. Budd expressed the idea that: "The origins and diversification of the animals, a serial of events that became manifest in the so-called 'Cambrian explosion' of ca 540   Ma, must necessarily be intimately tied into the evolution of their important organ systems. Of these, the nervous system must be considered to be of farthermost importance, not only because of its universality among animals autonomously from sponges and placozoans, but also because of the part it plays in coordination, sensing and indeed many other aspects of the life of an creature." (Budd, 2015). There is adequate show to firmly assert that in metazoans the nervous system/CNS in bilaterians (and cnidarians) took over the control of not only the behavior and physiology only too the building and maintaining the fauna structure and morphology (Cabej, 2018b).

This office implies sending instructions (=information) on what to do to the target cells, tissues and organs. By integrating and processing external and internal stimuli, the brain generates this epigenetic data in the class of electrical signals, which within the nervous system are translated into chemical signals to start signal cascades to express/suppress item genes and induce cell differentiation and organogenesis (Cabej, 2012b).

If the CNS indeed played a function in the Cambrian explosion, that office must exist conserved to some degree in the evolution of the extant taxa, for the evolutionary changes that happened during the Cambrian, ultimately derive from changes that occurred in the developmental pathways of ancestors of the extant taxa. Since developmental pathways are mostly conserved across metazoans at that place is reason to believe that developmental mechanisms of extant animals requite the states critical clues on the drivers of the developmental changes that brought about the Cambrian explosion. Besides, there is adequate observational bear witness on the office of the CNS in transgenerational inheritance of caused traits, which tin exist logically extrapolated for explaining mechanisms of evolutionary changes during the Cambrian. The machinery of the evolutionary change observed in the extant metazoans cannot be different from the one that was operational during the Cambrian. It cannot exist a tardily invention of evolution, for evolution is parsimonious and it would non bother to invent a new machinery of evolutionary change, unlike from the one it used during the Cambrian. As an efficient mechanism of induction of evolutionary changes, it would be promoted and conserved by the natural selection. The same can be said for the role of neurocognitive mechanisms in reproductive isolation of extant species in sympatry.

In the post-obit, a part of the uncontested evidence on the instructive part of the nervous system in molding brute morphology and organogenesis, transgenerational inheritance of caused traits, and neural mechanisms of reproductive isolation, and sympatric speciation will be presented.

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https://www.sciencedirect.com/science/commodity/pii/B9780128143117000044