Ontogeny and phylogeny of endothermy and torpor in mammals and birds

Endothermic thermoregulation in small, altricial mammals and birds develops at about one third to half of adult size. The small size and consequently high heat loss in these young should result in more pronounced energetic challenges than in adults. Thus, employing torpor (a controlled reduction of metabolic rate and body temperature) during development would allow them to save energy. Although torpor during development in endotherms is likely to occur in many species, it has been documented in only a few. In small, altricial birds (4 orders) and marsupials (1 order), which are poikilothermic at hatching/birth, the development of competent endothermic thermoregulation during cold exposure appears to be concurrent with the capability to display torpor (i.e. poikilothermy is followed by heterothermy), supporting the view that torpor is phylogenetically old and likely plesiomorphic. In contrast, in small, altricial placental mammals (2 orders), poikilothermy at birth is followed first by a homeothermic phase after endothermic thermoregulation is established; the ability to employ torpor develops later (i.e. poikilothermy-homeothermy-heterothermy). This suggests that in placentals torpor is a derived trait that evolved secondarily after a homeothermic phase in certain taxa perhaps as a response to energetic challenges. As mammals and birds arose from different reptilian lineages, endothermy likely evolved separately in the two classes, and given that the developmental sequence of torpor differs between marsupials and placentals, torpor seems to have evolved at least thrice.     

Genomics and microarray for detection and diagnostics

Genomics provided biomedical scientists an inventory of all genes and sequences present in a living being. This provides an unique opportunity to the scientists to predict and study biological functions of these genes. The changes in the gene expression regulated by genomic sequences therefore reflect changes in the molecular processes working in a cell or tissue in response to external factors including exposure to toxic compounds and pathogens. Microarray offers a biotechnological revolution with the help of DNA chemistry, silicon chip technology and optics to be used to monitor gene expression for thousands of genes in one single experiment. Briefly, 20,000 to 100,000 unique DNA molecules get applied by a robot to the surface of silicon wafers (approximately the size of a microscope slide). Using a single microarray experiment, the expression level of 20,000 to 100,000 genes will be examined in one single experiment. Genomics and microarray have a significant role and impact on the design and development of modern detection and diagnostic tools in several different ways. Microarray tools are now used on regular basis for monitoring gene expression of large number of genes and also frequently applied to DNA sequence analysis, immunology, genotyping, and molecular diagnosing. For diagnostics, these tools can be used to distinguish and differentiate between different DNA fragments that differ by as little as a single nucleotide polymorphism (SNP). These microarrays can be divided based on the gene density spots that will be high density (>10,000 spots) per slide, medium (< 1000 > 100) and low density (< 100). High-density arrays have proven to be very useful in disease diagnosis especially in diagnosis and classification of different types of cancers. These microarray tools hold tremendous potential for pathogen detection, which will be comprised, of unique sets of genes (also referred to as "signatures") able to unambiguously identify the species and strain of pathogens of interest.     

Neurosecretion and Salt and Water Balance in the Annelida and Crustacea

The possible role of the neurosecretory system in regulationof salt and water has been studied in the annelids and crustaceans.In the earthworm, Lumbricus terrestris, a brain factor influences'the salt and osmotic concentration of the blood and coelomicfluid. Removal of the brain results in the increase of waterinflux with a decrease in the salt and osmotic concentrationsof the body fluids. The decreases in salt and osmotic concentrationscan be prevented by the implantation of the brain or the injectionof brain homogenates. In the freshwater crayfish, Procambarus clarkii, a factor, presumablysecreted in the brain and released in the eyestalk, seems tomaintain the normal permeability of the body surfaces to water.Eyestalk removal, which eliminates the release site, resultsin the increased influx of water with a decrease in the saltconcentration of the blood. A brain factor also seems to beinvolved in maintaining the sodium and osmotic concentrationsof the blood. In the semi-terrestrial grapsid crab, Metopograpsus messor,the thoracic ganglion, under the control of an eyestalk element,secretes a factor involved in increasing the permeability ofthe body surfaces to water. The removal of the eyestalks, theimplantation of the thoracic ganglion, or the injection of extractsof thoracic ganglia, results in changes in the osmotic concentrationof the blood tending toward that of the medium. In all threespecies studied, the neuroendocrine factors seem to be involvedprimarily in the regulation of the permeability of the bodysurfaces to water.     

Convection and diffusion in tissues and tissue cultures

The relative importance of transport by diffusion and convection in permeable tissues is investigated in three-dimensional structures. The transport of a solute takes place from a number of sources embedded in the tissue, to a number of sinks similarly embedded. An enhancement factor E is defined to be the ratio of the transport rate in the presence of a pressure difference between the sources and sinks, to the transport rate without a pressure difference. It is shown that E is a unique function of a parameter W, which characterizes the properties of the tissue and the pressure difference. This relation is independent of the number or the geometries of the sources and sinks.This relation is compared with experimental data obtained in a hollow fiber tissue culture device, with two sets of hollow fibers kept at different pressures. This relation is also used to estimate the importance of convection in vivo for a wide range of mammalian tissues and solute molecules.     

Azaperone and azaperone-ketamine as a neuroleptic sedative and anesthetic in rats and mice

Azaperone alone and combined with ketamine were evaluated as sedative and anesthetic agents in outbred rats and mice. Using azaperone alone the duration of immobility was 1.9 to 10.8 hours for mice and 0.9 to 2.4 hours for rats. The withdrawal reflex was not eliminated from mice receiving azaperone alone; however, the withdrawal reflex was eliminated from 0.9 to 2.4 hours in rats receiving azaperone. Azaperone produced a tachypnea in rats and male mice while a depressed respiratory rate was observed in female mice. Using azaperone combined with ketamine, the duration of immobilization was 1.1 to 8.8 hours for mice and 1.3 to 6.0 hours for rats. The duration loss of the withdrawal reflex, which was used as an indication of surgical anesthesia, was 0.9 to 1.8 hours for mice and 1.0 to 6.0 hours for rats. An increase in respiratory rate was observed in rats given the combination while mice given the combination showed transient tachypnea followed by bradypnea. Overall, azaperone alone was shown to provide sedation in mice as compared to a dose dependent anesthesia in rats. The azaperone-ketamine combination produced a surgical plane of anesthesia in both rats and mice. Azaperone and the azaperone-ketamine combination appear to be a suitable alternative to sedatives and anesthetics currently used in rats and mice.     

Obstetrics and gynecology: AIDS and pregnancy

The Scientific Board of the California Medical Association presents the following inventory of items of progress in obstetrics and gynecology. Each item, in the judgment of a panel of knowledgeable physicians, has recently become reasonably firmly established, both as to scientific fact and important clinical significance. The items are presented in simple epitome and an authoritative reference, both to the item itself and to the subject as a whole, is generally given for those who may be unfamiliar with a particular item. The purpose is to assist busy practitioners, students, research workers, or scholars to stay abreast of these items of progress in obstetrics and gynecology that have recently achieved a substantial degree of authoritative acceptance, whether in their own field of special interest or another.The items of progress listed below were selected by the Advisory Panel to the Section on Obstetrics and Gynecology of the California Medical Association and the summaries were prepared under its direction.     

Number and evolutionary conservation of alpha- and beta-tubulin and cytoplasmic beta- and gamma-actin genes using specific cloned cDNA probes

A partial library of cloned human DNA was screened for sequences represented on and specific to the X chromosome. The library was constructed from Bam HI-digested human DNA from cells with X chromosome polyploidy, and was cloned in pBR322. The screening was performed by individually hybridizing ³²P-labeled cloned plasmids to Southern blots containing Bam HI-digested DNA from mouse-human hybrid cells having the human X chromosome and from derivative hybrids lacking the human X. Of 45 clones assayed, 33 contained sequences homologous to ones represented many times on the X. In situ hybridization to metaphase chromosomes demonstrated that at least four of these clones were homologous to autosomes as well. Only one of the 18 clones of this kind tested cross-hybridized with another. Two recombinant plasmids were shown to be derived from the X chromosome and to be X chromosome-specific by three criteria: they hybridized to a single band in the Southern blots of Bam HI-digested DNA from hybrid cells containing the X chromosome; they hybridized to a band of the same molecular weight as did the inserted DNA fragment; and they showed a dosage effect when hybridized to Southern blots of Bam HI-digested DNA from XY and XXX cells. One of these hybridized as a single-copy or low-order reiterated sequence in a Cot analysis using male DNA as driver. Our methods can be applied to the identification of any chromosome-specific clone. The two X-specific clones identified here should be useful in investigating the mechanism of X inactivation and in isolating a Barr body.     

Hip Circumference and Cardiovascular Morbidity and Mortality in Men and Women

Objective: It has recently been demonstrated that, in middle‐aged women, a wide hip circumference is a protective factor for a number of health endpoints in later years. The effect seems to be independent of both overweight and waist circumference. This paper aims to replicate this finding in another population‐based sample consisting of women and men. Research Methods and Procedures: This was a prospective observational study consisting of a random subset of adult Danes. A total of 2987 subjects born in 1922, 1932, 1942, or 1952 and 35, 45, 55, or 65 years of age (at examination in 1987 to 1988) participated in the Danish MONICA (MONItoring trends and determinants of CArdiovascular disease) project, with measurements of height, weight, and hip and waist circumference taken. Through personal identification numbers, incidence of coronary heart disease (CHD) and cardiovascular disease (CVD) until the end of 1998 and all causes of death until 2001 were retrieved from the National Registers of Hospital Discharge. There was an average of 10 years of follow‐up for incidence of CVD and CHD and 13 years of follow‐up for total mortality. Results: Large hip circumference, relative to body size and waist circumference, predicted less incidence of CVD, CHD, and total death in women. This was not the case in men; BMI and waist circumference were the strongest independent predictors. Discussion: A large hip circumference seems to have independent and positive effects on CVD and CHD morbidity and mortality in women, but no protective effect on cardiovascular health in men. However, a borderline significant protective effect on total mortality was observed.     

Skin and core temperature response to partial- and whole-body heating and cooling

1. Human subjects were exposed to partial- and whole-body heating and cooling in a controlled environmental chamber to quantify physiological and subjective responses to thermal asymmetries and transients.

2. Skin temperatures, core temperature, thermal sensation, and comfort responses were collected for 19 local body parts and for the whole body.

3. Core temperature increased in response to skin cooling and decreased in response to skin heating.

4. Hand and finger temperatures fluctuated significantly when the body was near a neutral thermal state.

5. When using a computer mouse in a cool environment, the skin temperature of the hand using the mouse was observed to be 2–3 °C lower than the unencumbered hand.     

Cellular impermeability and uptake of biocides and antibiotics in gram-positive bacteria and mycobacteria

Gram-positive bacteria possess a permeable cell wall that usually does not restrict the penetration of antimicrobials. However, resistance due to restricted penetration can occur, as illustrated by vancomycin-intermediate resistant Staphylococcus aureus strains (VISA) which produce a markedly thickened cell wall. Alterations in these strains include increased amounts of nonamidated glutamine residues in the peptidoglycan and it is suggested that the resistance mechanism involves 'affinity trapping' of vancomycin in the thickened cell wall. VISA strains have reduced doubling times, lower sensitivity to lysostaphin and reduced autolytic activity, which may reflect changes in the D-alanyl ester content of the wall and membrane teichoic acids. Mycobacterial cell walls have a high lipid content, which is assumed to act as a major barrier to the penetration of antimicrobial agents. Relatively hydrophobic antibiotics such as rifampicin and fluoroquinolones may be able to cross the cell wall by diffusion through the hydrophobic bilayer composed of long chain length mycolic acids and glycolipids. Hydrophilic antibiotics and nutrients cannot diffuse across this layer and are thought to use porin channels which have been reported in many species of mycobacteria. The occurrence of porins in a lipid bilayer supports the view that the mycobacterial wall has an outer membrane analogous to that of gram-negative bacteria. However, mycobacterial porins are much less abundant than in the gram-negative outer membrane and allow only low rates of uptake for small hydrophilic nutrients and antibiotics.     

Pets and pests in Roman and medieval Britain

Humans and other vertebrates interact in a variety of relationships which are inadequately described by a simple division of these other animals into wild, feral, tame, and domestic taxa. Discussion of the process and semantic meaning of domestication has largely taken place in the context of the adoption of settled agriculture, but is equally relevant to complex urban societies. Certain species adopted a synanthropic relationship in the first 'villages' of the early Holocene, and co-existence with pets has a similar antiquity. The nature of the relationship between people and their pets is complex, and scarcely amenable to archaeological investigation, as part of the mutual benefit has an emotional basis, or centres on the symbolic role of certain species within different societies. The status of Cats in medieval towns in Britain and Ireland is a case in point, with opinions varying from the exploitation of Cats for skins, through neglected feral living, to a pet status much as today. The truth probably subsumes all three interpretations. Rats seem to have adapted to commensalism in northern Europe more slowly than Mice, and there may be evidence that Rats were more vulnerable to changes in habitat. Archaeology can usefully examine the community ecology of Roman and medieval towns, but any such research must move away from simple concepts of wild or domestic status.     

Mandibular form and function in North American and European Adapidae and Omomyidae

Previous experimental and comparative studies among a wide variety of primate and nonprimate mammals provide a unique source of information for investigating the functional and phylogenetic significance of variation in the masticatory apparatus of Eocene primates. To provide a quantitative study of mandibular form and function in Eocene primates, the scaling of jaw dimensions and the development of symphyseal fusion was considered in a broad sample of North American and European Adapidae and Omomyidae. Statistical analyses indicate a significant size-related pattern of symphyseal fusion across Eocene primates, with larger taxa often having a greater degree of fusion than smaller species; this trend is also evident at the family level. As adapids are mostly larger than omomyids and these taxa show allometry of symphyseal fusion, this may explain why no omomyids evince complete fusion. Controlling for jaw size, species with greater symphyseal fusion tend to have more robust jaws than those with a lesser amount of fusion. Upon further examination, a primary reason why adapids have more robust mandibles than omomyids is associated with the presence of taxa with fused symphyses, and thus more robust jaws, in the adapid sample, whereas no omomyids have fused symphyses. In addition, there is little indication of a dietary effect, as measured by molar shear-crest development, on symphyseal fusion. Moreover, as there is no correlation between molar shear-crest development and skull size, this also points to the absence of a size-related pattern of dietary preference underlying the allometry of symphyseal fusion. Based on the interspecific and ontogenetic allometry of symphyseal ossification in Eocene primates, jaw-scaling patterns are used to further examine the functional determinants of fusion in this group. This study indicates that greater dorsoventral shear during mastication is a more likely factor than lateral transverse bending (“wishboning”) in the evolution of symphyseal fusion among “late-fusing” mammals like adapids and omomyids. Given that wishboning is an important functional determinant of symphyseal form in recent anthropoids, apparently the evolutionary development of marked wishboning occurs only in taxa that shift the timing of fusion to a growth stage preceding the onset of weaning (before adult masticatory patterns are fully developed) and perhaps first ossified the symphysis to counter elevated dorsoventral shear stress. As early anthropoids probably consisted of members varying interspecifically and ontogenetically in the degree of ossification, it is especially informative to analyze the adaptive setting in which anthropoid symphyseal fusion evolved from a similar primitive “prosimian” perspective. © 1996 Wiley-Liss, Inc.     

Neuromelanin and its Possible Protective and Destructive Properties

The function of neuromelanin is not known, but some properties of the pigment suggest a protective action. Its unique ability to accumulate and retain several compounds, such as various amines and a number of metals, may protect the pigment-containing neurons from high exposure to harmful substances. This possible mechanism of protection may however in certain instances be of a double-edged nature, as accumulation of neurotoxic agents with a high melanin affinity may cause toxic concentrations in the neuro-melanin-containing cells. MPTP (l-methyl-4-phenyl-l,2,3,6-tetrahydropyridine) seems to be such a compound, as it has been found to preferentially destroy neuromelanin-containing cells. The degree of MPTP neurotoxicity seems to be related to the amount of neuromelanin present in the particular species. It is possible that also manganese, which is known to cause an extrapyramidal disorder resembling Parkinson's disease, causes injury to neuromelanin-bearing neurons due to its melanin affinity. This mechanism may be involved in other forms of chemically induced Parkin-sonism and possibly also in idiopathic Parkinson's disease, although the offending agent remains to be discovered.     

Beyond explanation and understanding: Anthropology and hermeneutics

Conclusion The fact that Ricoeur's influential essay on the model of the text was published twenty years ago has not in any way reduced its significance for addressing critical issues of interpretation in the human sciences. However, Ricoeur's suggestion that we turn to structural linguistics as a basis from which to develop a critical interpretive theory rooted in the logic of the human sciences has since been challenged, but not superseded, by the post-structuralist assertion that text, or human action as a text, lacks coherence. Jacques Derrida and his followers have argued that the objective of their method is to deconstruct a text which means to discover what it excludes through its representation. It is, therefore, a fiction, Derrida maintains, to presuppose that one can unveil the meaning or truth of a text, as the reading of a text must necessarily take place in its margins.Whatever may be the practical implications, or implications for praxis, in the assertion that a text lacks a unity or truth, I contend that the key question raised by Ricoeur, and not to my knowledge resolved by post-structuralism, is how to maintain a sense of action as meaningful while being able to grasp it critically. This question establishes a point of tension between human agency and the objective structural constraints to which it is subject, thus, as I have asserted, connecting the formal properties of a text to the conditions of its generation. Although I have argued that Ricoeur's moment of structural or semiotic mediation is faulted in that it locates oppositions or contradictions in the avowed worldlessness of the text's interior rather than in the historical process of humanity's self-formation, this weakness does not altogether eclipse the merit of his analogy between the interpretation of texts and human actions. To the contrary, Ricoeur has shown how it is possible through rejecting the methodological implications of an explanation and understanding dichotomy — or how emics and etics have come to be used in contemporary anthropology to distinguish types of theoretical constructs — to develop an interpretation theory with critical implications based on the logic of the human sciences. Anthropologists who resort to an exclusive explanation or etic position, through the drawing of nomological hypotheses, fail to recognize that cultural phenomena are intentional in that they owe their generation and identity to a historically constituted intersubjectivity. On the other hand, anthropologists who privilege the understanding position, which is highly prevalent in contemporary symbolic and interpretive anthropology, conceptualize this process as the logical reconstruction of the subjective intentions of actors, or in a more complex sense, the identification of meaning with context. Ricoeur has argued that the pursuit of an exclusive explanation or understanding theory is based upon an epistemological reduction. The privileging of theories based upon natural science explanation reduced the intersubjectivity of meaning to the classification and verification of facts, while theories based upon understanding reduce the dialectical movement of meaning to the ostensive reference of context. From either the exclusive explanation or understanding trajectories, the critical potentialities of anthropology are vitiated because the reflexive dimension of the interpretive process is absent. As Ricoeur has repeatedly emphasized, knowledge of remote historical periods, texts, or other cultures not only produces a comprehension of these phenomena as radically other, but also casts light onto our own life situation.Ricoeur's theory is important, therefore, for anthropologists and other students of the human sciences, because it combines an emphasis on mediation, or the critique of naive consciousness, with the conceptualization of human actions as intentional, communicative events. It therefore goes a long way towards bridging some of the deepest objections raised by the scientistic outlook against the method of versteben, while retaining the latter's emphasis on a hermeneutic understanding of social life. This bridge has been built without resorting to the objectivism of the natural sciences and by pursuing the logic of a method that is in concert with the unique object-subject of the human sciences.

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Mechanisms and function of flower and inflorescence reversion

Flower and inflorescence reversion involve a switch from floral development back to vegetative development, thus rendering flowering a phase in an ongoing growth pattern rather than a terminal act of the meristem. Although it can be considered an unusual event, reversion raises questions about the nature and function of flowering. It is linked to environmental conditions and is most often a response to conditions opposite to those that induce flowering. Research on molecular genetic mechanisms underlying plant development over the last 15 years has pinpointed some of the key genes involved in the transition to flowering and flower development. Such investigations have also uncovered mutations which reduce floral maintenance or alter the balance between vegetative and floral features of the plant. How this information contributes to an understanding of floral reversion is assessed here. One issue that arises is whether floral commitment (defined as the ability to continue flowering when inductive conditions no longer exist) is a developmental switch affecting the whole plant or is a mechanism which assigns autonomy to individual meristems. A related question is whether floral or vegetative development is the underlying default pathway of the plant. This review begins by considering how studies of flowering in Arabidopsis thaliana have aided understanding of mechanisms of floral maintenance. Arabidopsis has not been found to revert to leaf production in any of the conditions or genetic backgrounds analysed to date. A clear-cut reversion to leaf production has, however, been described in Impatiens balsamina. It is proposed that a single gene controls whether Impatiens reverts or can maintain flowering when inductive conditions are removed, and it is inferred that this gene functions to control the synthesis or transport of a leaf-generated signal. But it is also argued that the susceptibility of Impatiens to reversion is a consequence of the meristem-based mechanisms controlling development of the flower in this species. Thus, in Impatiens, a leaf-derived signal is critical for completion of flowering and can be considered to be the basis of a plant-wide floral commitment that is achieved without accompanying meristem autonomy. The evidence, derived from in vitro and other studies, that similar mechanisms operate in other species is assessed. It is concluded that most species (including Arabidopsis) are less prone to reversion because signals from the leaf are less ephemeral, and the pathways driving flower development have a high level of redundancy that generates meristem autonomy even when leaf-derived signals are weak. This gives stability to the flowering process, even where its initiation is dependent on environmental cues. On this interpretation, Impatiens reversion appears as an anomaly resulting from an unusual combination of leaf signalling and meristem regulation. Nevertheless, it is shown that the ability to revert can serve a function in the life history strategy (perenniality) or reproductive habit (pseudovivipary) of many plants. In these instances reversion has been assimilated into regular plant development and plays a crucial role there.     

Distribution and fate of aliphatic and aromatic hydrocarbons in Antarctic fauna and environment

With the depletion of oil resources in more accessible areas, those of remote regions are being considered or indeed are now being exploited. In many of these regions, especially the polar ones, little is known of the effects such exploitation will have on the environment. But it is known that the ecosystems are often subject to great stress by natural climatic conditions and additional burdens imposed by man may have catastrophic environmental effects. South Georgia, a sub-Antarctic island, has a history of industrial activity mainly concerned with whaling operations that peaked around 1925–1935 but has since declined to virtually nothing. Studies of the ecology of the area provided a unique opportunity to assess the long-term effects that such activities had on the ecosystem. Off the whaling stations a considerable amount of waste material, including fuel oil, was released into the bays and inevitably some of this material was deposited in the sediments. Chemical evidence in the form of both paraffinic and aromatic hydrocarbons still persists in the sediments. The implications of this persistence in relation to the possible influence of the low temperature conditions are discussed. The superficial sediments, marine biota and terrestrial plants, which since 1965 have returned virtually to a pristine state, contain hydrocarbons essentially similar to unpolluted areas around the coast of Britain. Relatively high levels of carcinogenic/mutagenic polynuclear aromatic hydrocarbons in surface sediments suggests a world-wide background of abiogenic hydrocarbons probably disseminated by airborne transport. This appears to indicate that contamination reaches even remote parts of the world in relatively undiminished quantities.     

Energetic and physiological correlates of prey handling and ingestion in lizards and snakes

In this review, we summarize the energetic and physiological correlates of prey handling and ingestion in lizards and snakes. There were marked differences in the magnitude of aerobic metabolism during prey handling and ingestion between these two groups, although they show a similar pattern of variation as a function of relative prey mass. For lizards, the magnitude of aerobic metabolism during prey handling and ingestion also varied as a function of morphological specializations for a particular habitat, prey type, and behavior. For snakes, interspecific differences in aerobic metabolism during prey handling seem to be correlated with adaptations for prey capture (venom injection vs. constriction). During ingestion by snakes, differences in aerobic metabolism might be due to differences in cranial morphology, although allometric effects might be a potentially confounded effect. Anaerobic metabolism is used for prey handling and ingestion, but its relative contribution to total ATP production seems to be more pronounced in snakes than in lizards. The energetic costs of prey handling and ingestion are trivial for both groups and cannot be used to predict patterns of prey-size selection. For lizards, it seems that morphological and ecological factors set the constraints on prey handling and ingestion. For snakes, besides these two factors, the capacity of the cardio-respiratory system may also be an important factor constraining the capacity for prey handling and ingestion.