Equations of heat distribution within the body

A vector integral equation describing heat distribution within the body has been derived. The factors considered are heat conduction, forced convection via the circulatory system, environmental exchange, metabolic heat production, and change in heat content. The vector partial differential equation and alternative forms incorporating boundary conditions were also developed. A difference equation based on a first-order approximation to the fundamental equations was derived to form the basis of a model for heat distribution within the body. It has been shown that factors involving conduction and convection must be considered independently unless the temperature of the blood flowing from a region of the body is equal to the average temperature of the tissue in that region. If this relation between tissue and blood temperature does exist, only a single temperature from each eleeent is needed to describe the heat distribution. In this latter case, models which ascribe all heat transfer to “equivalent” conduction or to convection can give valid predictions.     

Variation between and within the sexes in body size preferences

Although it is often assumed that males and females have mating preferences for larger individuals of the other sex, potential underlying differences between male and female preferences for body size are not commonly investigated. Here, sexual differences in body size preferences are examined in the poeciliid fish, Brachyrhaphis rhabdophora. Females preferred larger males to smaller males, but preference did not appear to be affected by female size. One population-level analysis for males did not indicate an overall preference for larger females. A closer examination, however, revealed an effect of male size on preference; larger males preferred larger females, while smaller males preferred smaller females. It appears then that females, regardless of size, share a preference for large males, but males differ in their behaviour, depending on their body size. In addition, while the degree of difference in size between paired females did not appear to affect male preference, the degree of difference in size between paired males strongly affected female preference; the greater the difference, the more strongly females preferred the larger male. Thus, intersexual selection is found to operate in both sexes, but how it operates appears to differ. Intrasexual and intersexual differences in mating behaviour may be missed when evaluating population-wide preferences. That is, there can be underlying differences in how the sexes respond and the consequences of such differences should be considered when investigating mate choice. The results are considered in terms of the evolution of mating preferences, alternative mating strategies, assortative mating, the maintenance of trait variation in a population, and current methods to evaluate mating preferences.     

Accessory carotid body within the parathyroid gland III of the chicken

In the chicken, the cranial and caudal parathyroid glands (parathyroid gland III and IV), which are connected to each other, are located adjacent to the carotid body. In the present study, we found that a mass of glomus cells surrounded by a thick layer of connective tissue was frequently distributed within the parathyroid gland III. The glomus cells in the parathyroid III, as well as those of the carotid body, expressed intense immunoreactivity for serotonin, chromogranin A, and tyrosine hydroxylase but no immunoreactivity for neuropeptide Y. The cells possessed long cytoplasmic processes containing dense-cored vesicles of 70–220 nm in diameter, and were in close association with sustentacular cells. In and around the glomus cell clusters of the parathyroid III, dense networks of varicose fibers showed immunostaining with the monoclonal antibody TuJ1 to a neuronspecific class III -tubulin isotype, c4. Furthermore, the distribution was also detected of numerous galanin-, vasoactive intestinal peptide (VIP)-, substance P-, and calcitonin gene-related peptide (CGRP)-immunoreactive fibers.     

Variations in body height within the course of a working day

Variation of body height during the day has been analyzed considering the influence of various occupations (standing, sitting, mixed) on the posture. In addition to this the following variables have been recorded on the 302 individuals under study: Sex, age, working time, time of getting up in the morning, kind of occupation, physique, sporting activities in the leisure-time, presence of defects of the spinal column, possibility of changes of the carriage at the working place and extensibility of the spinal column. The statistical analysis showed that with the exception of pathological alterations of the spinal column all these variables are influencing the variation of body height during the day. It could also be shown that the extensibility of the spinal column does not vary during the day. The author is discussing also ergonomical rules concerning the organization of working places for standing and sitting occupations. Finally some recommendations for the future organization of such places are given.     

Work that body: fin and body movements determine herbivore feeding performance within the natural reef environment

Herbivorous fishes form a keystone component of reef ecosystems, yet the functional mechanisms underlying their feeding performance are poorly understood. In water, gravity is counter-balanced by buoyancy, hence fish are recoiled backwards after every bite they take from the substrate. To overcome this recoil and maintain contact with the algae covered substrate, fish need to generate thrust while feeding. However, the locomotory performance of reef herbivores in the context of feeding has hitherto been ignored. We used a three-dimensional high-speed video system to track mouth and body kinematics during in situ feeding strikes of fishes in the genus Zebrasoma, while synchronously recording the forces exerted on the substrate. These herbivores committed stereotypic and coordinated body and fin movements when feeding off the substrate and these movements determined algal biomass removed. Specifically, the speed of rapidly backing away from the substrate was associated with the magnitude of the pull force and the biomass of algae removed from the substrate per feeding bout. Our new framework for measuring biting performance in situ demonstrates that coordinated movements of the body and fins play a crucial role in herbivore foraging performance and may explain major axes of body and fin shape diversification across reef herbivore guilds.     

Habitat primary production and the evolution of body size within the hartebeest clade

Local adaptation is a key process in the evolution of biological diversity but relatively few studies have identified the selective forces that drive trait divergence at low taxonomic levels, particularly amongst mammals. Variation in body size across taxa is fundamental as shown by allometric relationships with numerous physiological, morphological and life-history traits. Differences in adult size across cohorts within populations of temperate ungulates are determined by variation in trophic resource availability during growth, suggesting that natural selection might promote the evolution of size divergence across sister taxa through local adaptation to variation in habitat productivity. We tested this hypothesis in the hartebeest ( Alcelaphu s sp.), an antelope lineage including eight extant (or recently extinct) allopatric subspecies that evolved within the last million years and colonized all the African savannahs. We predicted that body size across the subspecies should correlate positively with habitat productivity across taxon ranges. Mean body size of all the hartebeest taxa was quantified using skull length from museum specimens, and climatic variables were used as surrogates of habitat productivity. Body size across subspecies was positively correlated with rainfall, suggesting that variation in habitat primary production may drive morphological evolution between taxa. Focusing at a low taxonomic level has allowed us to identify a critical selective force that may shape divergence in body size, without the confounding effect of variation in trophic niche. © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 92 , 431–440.     

Determining the sub-cellular localization of proteins within Caenorhabditis elegans body wall muscle

Determining the sub-cellular localization of a protein within a cell is often an essential step towards understanding its function. In Caenorhabditis elegans, the relatively large size of the body wall muscle cells and the exquisite organization of their sarcomeres offer an opportunity to identify the precise position of proteins within cell substructures. Our goal in this study is to generate a comprehensive "localizome" for C. elegans body wall muscle by GFP-tagging proteins expressed in muscle and determining their location within the cell. For this project, we focused on proteins that we know are expressed in muscle and are orthologs or at least homologs of human proteins. To date we have analyzed the expression of about 227 GFP-tagged proteins that show localized expression in the body wall muscle of this nematode (e.g. dense bodies, M-lines, myofilaments, mitochondria, cell membrane, nucleus or nucleolus). For most proteins analyzed in this study no prior data on sub-cellular localization was available. In addition to discrete sub-cellular localization we observe overlapping patterns of localization including the presence of a protein in the dense body and the nucleus, or the dense body and the M-lines. In total we discern more than 14 sub-cellular localization patterns within nematode body wall muscle. The localization of this large set of proteins within a muscle cell will serve as an invaluable resource in our investigation of muscle sarcomere assembly and function.     

The occurrence and distribution of certain polypeptides within the human carotid body

Summary Both carotid bodies from 26 patients coming to necropsy were fixed in 10% neutral buffered formalin and sections 4 m thick were stained for various peptides by use of the immunogold technique. The results show that the human carotid body contains met- and leu-enkephalin, substance P, vasoactive intestinal peptide (VIP), neurotensin and bombesin. The distribution of these six peptides within the carotid body differs. Thus met- and leu-enkephalin are both present predominantly within glomic chief cells but with a marked tendency to favour the dark variant of these cells. Substance P and VIP both show a weak immunoreactivity in comparison to the enkephalins and are present in all three variants of chief cell. Neurotensin shows the weakest immunoreactivity of all and is restricted to a few glomic chief cells in a minority of cases. Bombesin also shows a weak immunoreactivity in glomic chief cells but a strong reaction in glomic arteries and arterioles. In these vessels bombesin appears to be confined to smooth muscle cells in the media but we cannot say whether it is secreted by them or merely bound to receptor sites on their membranes. These findings are related to quantitative data on the concentration of peptides in the human carotid body from a previous paper with which we were associated.     

Segment polarity genes and cell patterning within the Drosophila body segment.

The formation of complex structures in any multicellular organism requires cooperative behaviour within cell populations. Genetic and molecular analysis of pattern formation in the Drosophila embryo is providing us with new insights into the cellular basis of this process, implicating a diversity of molecules, some familiar, others novel, in intercellular communication.     

c-Myc localization within the nucleus: evidence for association with the PML nuclear body

Definitive localization of c-Myc within the nucleus is important to fully understand the regulation and function of this oncoprotein. Studies of c-Myc distribution, however, have produced conflicting results. To overcome technical challenges inherent in c-Myc cytology, we use here three methods to visualize c-Myc and in addition examine the impact of proteasome inhibition. EYFP or HA-tagged Myc was reintroduced by stable transfection into myc null diploid rat fibroblasts, replacing endogenous Myc with tagged Myc expressed at or near normal levels. This tagged Myc is shown to functionally replace the endogenous Myc by restoration of normal cell morphology and growth rate. We were able to confirm key findings using antibodies to the endogenous c-Myc and/or its partner, Max. Contrary to some published reports, by all three methods the c-Myc protein in rat fibroblasts distributes predominantly throughout the nucleus in a dispersed granular pattern, avoiding the nucleolus. Importantly, however, several findings provide evidence for an unanticipated relationship between c-Myc and PML nuclear bodies, which is enhanced under conditions of proteasome inhibition. Evidence of Max concentration within PML bodies is shown both with and without proteasome inhibition, strengthening the relationship between PML bodies and Myc/Max. Some accumulation of Myc and Max in nucleoli upon proteasome inhibition is also observed, although co-localization of ubiquitin was only seen with PML bodies. This work provides a comprehensive study of c-Myc distribution and also presents the first evidence of a relationship between turnover of this oncoprotein and PML nuclear bodies, known to break down in certain cancers.     

Multisensory integration and the body schema: close to hand and within reach

There has been a recent and dramatic growth of interest in the psychological and neural mechanisms of multisensory integration between different sensory modalities. Much of this recent research has focused specifically on how multisensory representations of body parts and of the 'peripersonal' space immediately around them, are constructed. Research has also focused on how this may lead to multisensorially determined perceptions of body parts, to action execution, and even to attributions of agency and self-ownership for the body parts in question. Converging evidence from animal and human studies suggests that the primate brain constructs various body-part-centred representations of space, based on the integration of visual, tactile and proprioceptive information. These representations can plastically change following active tool-use that extends reachable space and also modifies the representation of peripersonal space. These new results indicate that a modern cognitive neuroscience approach to the classical concept of the 'body schema' may now be within reach.     

Kinase activity controls the sorting of the epidermal growth factor receptor within the multivesicular body

We compared the internalization and intracellular sorting of epidermal growth factor receptor (EGF-R) and point mutant kinase-negative EGF-R separately expressed in NIH 3T3 cells lacking endogenous receptor. Both EGF-Rs internalized rapidly, but kinase-negative receptor was surface down-regulated only with monensin or at 20 degrees C. Furthermore, EGF internalized by mutant receptor alone was, in significant proportion, returned to the cell surface undegraded. Hence unlike wild-type receptor, kinase-negative EGF-R recycles. By electron microscopy the early pathways of endocytosis for the two receptors were identical; however, after 10-20 min the pathways diverged at the multivesicular body (MVB). Wild-type EGF-R, destined for degradation, localized to internal vesicles, while kinase-negative EGF-R, destined for recycling, localized to surface membranes of the MVBs and moved to small tubulovesicles. We conclude that sorting of internalized receptor for degradation or recycling can occur through spatial segregation within the MVB, and sorting of EGF-R is controlled by tyrosine kinase activity.     

Movement of water within the body of sheep fed at maintenance under thermoneutral conditions

Two mature Border Leicester x Merino wethers were maintained with continuous feeding under thermoneutral conditions. Their water balance was recorded for 2 weeks; at the beginning of each week they were given a dose of tritiated water (TOH) into the pulmonary artery or the rumen and samples were taken from both the pulmonary artery and the rumen. A four-compartment model was developed which simultaneously fitted the balance and tracer data. The half-time of TOH in body water was 6.7 days for one sheep and 7.6 days for the other; TOH space was about 55% of liveweight in both sheep. The bidirectional flux of water between the plasma-accessible compartment and 'bound' intracellular water averaged 45 litres per hour and that between plasma-accessible water and rumen water averaged 3.2 litres per hour. The mean residence times of a water molecule in the rumen were, for the two sheep, 60 and 63 min and the time constants for flow from the rumen were 12.3 and 13.4 h. Consideration of the rumen water balance suggested that there was net movement of water from the rumen to the plasma at about 200 ml/h; diffusion accounted for 86% of the influx to and 92% of the efflux from the rumen.     

Placement of genes for ribosomal RNA within the nucleolar organizing body of Zea mays

A maize strain that carried a reciprocal translocation between chromosome 6 and a B chromosome (TB6a) was used in this study. The break in chromosome 6 transected the nucleolar organizing body at approximately the cytological midpoint, and the break in the B was one third the distance from its distal end. As a result both chromosomes 6-B and B-6 contained a portion of the nucleolar organizing body. Because of nondisjunction of chromosome B-6 at the second microspore division after meiosis, crosses between plants carrying six to eight of these chromosomes and homozygous for chromosome 6-B, produced progeny that had between one and about nine chromosomes B-6. Thus a quantitative series of nucleolar organizing body fragments was produced. Molecular hybridization experiments with ribosomal-RNA and DNAs extracted from these plants revealed 1) that genes coding for rRNA were located in the nucleolar organizer fragments on either side of the original translocation breakpoint and 2) that with each additional nucleolar organizer fragment provided by the chromosomes B-6, there is a proportional increase in ribosomal-DNA content. The most important conclusion to be derived from these studies is that the vast majority, if not all, of the ribosomal-RNA genes are unambiguously located within the nucleolar organizing body [with possibly a small percentage of them in the adjacent achromatic gap (Givens and Phillips, 1973, abstract)]. This placement is consistent with that of Givens and Phillips who used a quite different cytogenetic approach. The preciseness of previous determinations in Drosophila, and Xenopus allowed their placement only to the region of the nucleolar organizer. This study showed no evidence for a disproportionate replication of rDNA as a function of different amounts of nucleolar organizing material.Abbreviations rDNA ribosomal-DNA - rRNA ribosomal-RNA - NO nucleolar organizer     

A single-nucleotide mutation within the TBX3 enhancer increased body size in Chinese horses

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Sexual size dimorphism within species increases with body size in insects

Studies examining interspecific differences in sexual size dimorphism (SSD) typically assume that the degree of sexual differences in body size is invariable within species. This work was conducted to assess validity of this assumption. As a result of a systematic literature survey, datasets for 158 insect species were retrieved. Each dataset contained adult or pupal weights of males and females for two or more different subsets, typically originating from different conditions during immature development. For each species, an analysis was conducted to examine dependence of SSD on body size, the latter variable being used as a proxy of environmental quality. A considerable variation in SSD was revealed at the intraspecific level in insects. The results suggest that environmental conditions may strongly affect the degree, though not the direction of SSD within species. In most species, female size appeared to be more sensitive to environmental conditions than male size: with conditions improving, there was a larger relative increase in female than male size. As a consequence, sexual differences in size were shown to increase with increasing body size in species with female-biased SSD (females were the larger sex in more than 80% of the species examined). The results were consistent across different insect orders and ecological subdivisions. Mechanisms leading to intraspecific variation in SSD are discussed. This study underlines the need to consider intraspecific variation in SSD in comparative studies.     

Variation of body size within and between wild populations of Drosophila buzzatii

Four populations of the cactophilous species D. buzzatii have been compared with respect to the phenotypic variation of thorax and wing length of wild versus laboratory reared flies. Three of the strains were intercrossed to provide parent, F₁ and F₂ comparisons as a test of co-adaptation. The genetic contribution to phenotypic variation of laboratory reared flies was estimated from the correlation between sibs derived from random pair mating and reared individually in separate cultures. The average natural temperature during development was estimated from the relations between the wing/thorax ratio and temperature in laboratory tests.The variance of thorax and wing length of wild flies was several times greater than that of laboratory reared flies and the increase was attributed primarily to variation in larval food supply although temperature fluctuation is also important. There was no evidence of heterosis or F₂ break-down in the crosses. For two of the populations the heritability of thorax length was high, 60–70%, and substantially lower for the third. The average temperature estimated from the wing/thorax/temperature relationship differed between sites. The reduction of body size below the potential maximum averaged 30% for two and 20% for the other population, with a wide spread about these values. The evidence is discussed in relation to assessing the nature of ecological variation by comparing the variation of morphological traits in wild and laboratory reared flies.