On the role of the pineal in thermoregulation in the pigeon

Diurnal rhythm in body temperature of pigeons subjected to different experimental conditions (pinealectomized, sham-operated, melatonin-implanted, cold-exposed) was studied under a 12 h light and 12 h dark regimen. The body temperature of pigeons during photophase was higher than that during scotophase in the normal as well as every treatment group studied. Pinealectomized pigeons showed higher body temperature in the photophase as well as scotophase, than that of the normal and sham-operated birds when examined 2 or 3 weeks following the post-surgical acclimatization to 25 or 3 degrees C. However, subcutaneous implantation of melatonin pellets into pinealectomized pigeons nullified or even reversed the hyperthermic effect of pinealectomy. Exposure of pigeons to--18 degrees C for 280 min during photophase as well as scotophase, produced a marked drop in body temperature in pinealectomized, sham-operated and normal pigeons. The pinealectomized pigeons exhibited a higher body temperature than that of the sham-operated and normal ones when exposed to--18 degrees C during the photophase, but not during the scotophase. It was concluded that while the pineal is not necessary for maintaining the daily thermal rhythm in the avian body, it has a thermoregulatory role, in that it prevents rise in body temperature in warm (25 degrees C) acclimatized and chronic cold (3 degrees C) exposed birds. In acute short-term cold (--18 degrees C) exposure however, the temperature regulatory role of the pineal was not effective during the scotophase.     

Circadian rhythm in olfactory response in the antennae controlled by the optic lobe in the cockroach

The olfactory response in antennae of the cockroach, Leucophaea maderae, was investigated by measuring electroantennograms (EAGs) in restrained animals. The amplitude of the EAG response to pulses of ethyl acetate, octanol, or fenchone, exhibited a robust, light entrained, circadian rhythm that persisted at least 14 days in constant darkness. Dilution-response curves measured at the peak and trough of the rhythm indicated there was a 10-fold change in sensitivity. The EAG rhythm was abolished by severing the optic tracts, while entrainment was abolished by ablation of the compound eyes. The results indicate that the circadian system modulates olfactory sensitivity in the antennae and that the rhythm is driven by a circadian pacemaker in the optic lobes that is entrained by photoreceptors in the compound eyes.     

Higher temperatures during development reduce body size in the zebra finch in the laboratory and in the wild

The most commonly documented morphological response across many taxa to climatic variation across their range follows Bergmann's rule, which predicts larger body size in colder climates. In observational data from wild zebra finches breeding across a range of temperatures in the spring and summer, we show that this relationship appears to be driven by the negative effect of high temperatures during development. This idea was then experimentally tested on zebra finches breeding in temperature‐controlled climates in the laboratory. These experiments confirmed that those individualso produced in a hot environment (30 °C) were smaller than those produced in cool conditions (18 °C). Our results suggest a proximate causal link between temperature and body size and suggest that a hotter climate during breeding periods could drive significant changes in morphology within and between populations. This effect could account for much of the variation in body size that drives the well‐observed patterns first described by Bergmann and that is still largely attributed to selection on adult body size during cold winters. The climate‐dependent developmental plasticity that we have demonstrated is an important component in understanding how endotherms may be affected by climate change.     

ECVAM's role in the implementation of the Three Rs concept in the field of biologicals

Biologicals can be defined as products that are derived from living organisms or are produced by them. They include vaccines, hormones, monoclonal and polyclonal antibodies, blood products and rDNA products. The production of conventionally produced biologicals requires an extensive batch-related quality control, to ensure that these products are both safe and potent. As several of the control tests rely on animal models, it is inevitable that the large numbers of animals are used. Many initiatives have been undertaken in the last few decades to reduce and refine the use of animals in this area. ECVAM has been involved in many activities to support the development, validation and implementation of these Three Rs methods. The role that ECVAM has played in a number of validation studies is summarised. It is concluded that ECVAM should continue to support the activities that have been shown to be successful, preferably in collaboration with the regulatory bodies.     

Sex difference in volume of the ventromedial nucleus of the hypothalamus in the rat

The volume of the ventromedial nucleus of the hypothalamus (VMN) of normal male rats was significantly greater than that of normal female rats. Castration of day 1 neonatal males significantly reduced the volume of the VMN to a level comparable with that of normal females. However, the VMN volume was no longer influenced by castration on day 7. Injection of 1.25 mg testosterone propionate to 5- to 15-day-old females did not have any significant effect on the volume of the VMN. These results indicate that the volume of the VMN is sexually dimorphic and is modified by internal secretion of neonatal testes.     

Asymmetry in the dopamine content in the nucleus accumbens and the motor preference in rats

A number of published studies reported a correlation between the paw preference in mice and asymmetry of tissue concentrations of dopamine (DA) and DA metabolites measured in the nucleus accumbens (NAcb) the DA concentration being higher in the nucleus ipsylateral to a preferred paw. This study aimed to investigate whether such asymmetry existed in rats. The paw preference was defined by reaching into a small horizontal tube for a food pellet. Tissue concentration of DA was measured by high-performance liquid chromatography with electrochemical detection. It was shown that the DA concentration in the left NAcb was significantly higher in "left-handed" rats than in "right-handed" animals. Within the group of "right-handers", the DA concentration was significantly higher in the right NAcb than in the left NAcb. The results confirm in part the experimental data obtained in mice and support the hypothesis that the paw preference is paralleled by elevated tissue DA in the ipsylateral NAcb of rodents.     

Selenocysteyl-tRNA occurs in the diatom Thalassiosira and in the ciliate Tetrahymena

Selenocysteyl-tRNAs that decode UGA were identified previously in animal and bacterial cells and the genes for these tRNAs have been shown to be widespread in animals and eubacteria. In the present study, we identify a selenocysteyl-tRNA that codes for UGA in Thalassiosira pseudonana, which is a diatom, and in Tetrahymena borealis, which is a ciliate. The fact that these very diverse unicellular organisms also contain a selenocysteyl-tRNA suggests that selenocysteine-containing proteins and the use of UGA as a codon for selenocysteine are widespread, if not ubiquitous, in nature.     

Oxytocin in the periaqueductal grey regulates nociception in the rat

Studies have demonstrated that oxytocin (OXT) plays important roles in pain modulation in the central nervous system, and there are OXT receptors in the periaqueductal grey (PAG). The experiment was designed to investigate the effect of OXT in the PAG on antinociception. The results showed that (1) intra-PAG injection of OXT increased the pain threshold, whereas the local administration of the high specific OXT receptor antagonist, desGly-NH(2), d(CH(2))(5)[D-Tyr(2), Thr-sup-4]OVT decreased the pain threshold in a dose-dependent manner; (2) Pain stimulation could elevate OXT concentration in the PAG perfusion liquid. The data suggested that OXT in the PAG was involved in the antinociceptive process through the OXT receptor.     

Birds in the matrix: the role of agriculture in avian conservation in the Taita Hills,Kenya

Agricultural conversion of tropical forests is a major driver of biodiversity loss. Slowing rates of deforestation is a conservation priority, but it is also useful to consider how species diversity is retained across the agricultural matrix. Here, we assess how bird diversity varies in relation to land use in the Taita Hills, Kenya. We used point counts to survey birds along a land‐use gradient that included primary forest, secondary vegetation, agroforest, timber plantation and cropland. We found that the agricultural matrix supports an abundant and diverse bird community with high levels of species turnover, but that forest specialists are confined predominantly to primary forest, with the matrix dominated by forest visitors. Ordination analyses showed that representation of forest specialists decreases with distance from primary forest. With the exception of forest generalists, bird abundance and diversity are lowest in timber plantations. Contrary to expectation, we found feeding guilds at similar abundances in all land‐use types. We conclude that whilst the agricultural matrix, and agroforest in particular, makes a strong contribution to observed bird diversity at the landscape scale, intact primary forest is essential for maintaining this diversity, especially amongst species of conservation concern.     

Building capacity in the life sciences in the developing world

The fundamental challenge facing the scientific community is how to devise innovative strategies that will bring all developing countries into the "biological fold" and to do so in ways that will take full advantage of advances in the biological sciences to curb poverty, improve public health, and promote human development.     

Signatures of nitrogen limitation in the elemental composition of the proteins involved in the metabolic apparatus

Nitrogen (N) is a fundamental component of nucleotides and amino acids and is often a limiting nutrient in natural ecosystems. Thus, study of the N content of biomolecules may establish important connections between ecology and genomics. However, while significant differences in the elemental composition of whole organisms are well documented, how the flux of nutrients in the cell has shaped the evolution of different cellular processes remains poorly understood. By examining the elemental composition of major functional classes of proteins in four multicellular eukaryotic model organisms, we find that the catabolic machinery shows substantially lower N content than the anabolic machinery and the rest of the proteome. This pattern suggests that ecological selection for N conservation specifically targets cellular components that are highly expressed in response to nutrient limitation. We propose that the RNA component of the anabolic machineries is the mechanistic force driving the elemental imbalance we found, and that RNA functions as an intracellular nutrient reservoir that is degraded and recycled during starvation periods. A comparison of the elemental composition of the anabolic and catabolic machineries in species that have experienced different levels of N limitation in their evolutionary history (animals versus plants) suggests that selection for N conservation has preferentially targeted the catabolic machineries of plants, resulting in a lower N content of the proteins involved in their catabolic processes. These findings link the composition of major cellular components to the environmental factors that trigger the activation of those components, suggesting that resource availability has constrained the atomic composition and the molecular architecture of the biotic processes that enable cells to respond to reduced nutrient availability.     

Mutations in CHLOROPLAST RNA BINDING provide evidence for the involvement of the chloroplast in the regulation of the circadian clock in Arabidopsis

The Arabidopsis circadian system regulates the expression of up to 36% of the nuclear genome, including many genes that encode photosynthetic proteins. The expression of nuclear-encoded photosynthesis genes is also regulated by signals from the chloroplasts, a process known as retrograde signaling. We have identified CHLOROPLAST RNA BINDING (CRB), a putative RNA-binding protein, and have shown that it is important for the proper functioning of the chloroplast. crb plants are smaller and paler than wild-type plants, and have altered chloroplast morphology and photosynthetic performance. Surprisingly, mutations in CRB also affect the circadian system, altering the expression of both oscillator and output genes. In order to determine whether the changes in circadian gene expression are specific to mutations in the CRB gene, or are more generally caused by the malfunctioning of the chloroplast, we also examined the circadian system in mutations affecting STN7, GUN1, and GUN5, unrelated nuclear-encoded chloroplast proteins known to be involved in retrograde signaling. Our results provide evidence that the functional state of the chloroplast may be an important factor that affects the circadian system.     

Changes in the activity of alcohol dehydrogenase isoenzymes during the estrus cycle in the vagina of the rat

In rodents, the vaginal epithelium undergoes cyclical changes with an alternating pattern of keratinization and mucification. It has been known for decades that vitamin A and its active form retinoic acid are responsible for normal epithelial homeostasis. However, it has not so far been certain which enzymes catalyze the first and rate-limiting step in retinoic acid synthesis. By means of microdissection and ultrathin-layer gel electrophoresis, alcohol dehydrogenase isoenzyme activity was determined quantitatively in the various layers of the vaginal mucous membrane. It was found that, in the rat, only alcohol dehydrogenase 3 and 4 are expressed. Marked cyclical changes of alcohol dehydrogenase 4 activity in the stratum germinativum of the vaginal epithelium strongly support the assumption that this isoenzyme is responsible for retinoic acid synthesis, and that it is essential for the changes accompanying keratinization and mucification.     

Kinetics of the changes in the electrophoretic mobility of ascitic tumor cells differing in the sedimentation rate in the tumor growth process

The electrophoretic mobility of the ascitic tumor cells with different rates of sedimentation was measured by photographic registration of summarizing traces in the electrophoretic chamber. Changes in electrophoretic mobility of these cells during tumour growth are described. A conclusion is made that these changes are not connected with the proliferative activity of the tumour. It was shown that cells with low densities appeared in the late period of the tumor growth.     

A re-examination of the role of the nucleus in generating the circadian rhythm in Acetabularia.

The role of the nucleus in the generation of the circadian rhythm in Acetabularia has been nuclear. Early experiments showed that the plant could exhibit a circadian rhythm in the absence of a nucleus. However, other experiments appeared to show that the nucleus could impart phase information to the rhythm, and so therefore must be a part of the system that generates the rhythm. We have conducted experiments similar to these--in particular, one in which the nuclear end of the plant was entrained on a light-dark cycle that was opposite that of the rest of the plant. The phase of the free-running rhythm of this type of plant is not consistent with the conclusion that the nucleus is part of the circadian oscillator. We have also tried entraining opposite ends of plants with no nuclei on opposite light-dark cycles. The ultimate phases of these plants appear to be nearly random. A possible interpretation of these experiments is discussed.     

Changes in the Redox State in the Retina and Brain During the Onset of Diabetes in Rats

Diabetic retinopathy is thought to result from chronic changes in the metabolic pathways of the retina. Hyperglycemia leads to increased intracellular glucose concentrations, alterations in glucose degradation and an increase in lactate/pyruvate ratio. We measured lactate content in retina and other ocular and non-ocular tissues from normal and diabetic rats in the early stages of streptozotocin-induced diabetes. The intracellular redox state was calculated from the cytoplasmic [lactate]/[pyruvate] ratio.Elevated lactate concentration were found in retina and cerebral cortex from diabetic rats. These concentrations led to a significant and progressive decrease in the NAD⁺/NADH ratio, suggesting that altered glucose metabolism is an initial step of retinopathy. It is thus possible that tissues such as cerebral cortex have mechanisms that prevent the damaging effect of lactate produced by hyperglycemia and/or alterations of the intracellular redox state     

Race and ethnicity in the construction of the nation in Spain: the case of the Maragatos

Nationalism and its counterpart, modernism, are projects that involve the attempt to homogenize and incorporate the masses through the creation of a majority identity that usually leads to the classification of certain deviant groups as ‘others’. In Spain, civic and ethnic nationalisms driven by the state have historically drawn on cultural and biological notions of ethnicity and race to construct a representation of the Maragatos as ‘cursed peoples’, while at the same time homogenizing and incorporating them into the nation in practice. By tracing a genealogy of the origins and evolution of the representations of Maragato otherness created during the Enlightenment era, the Franco dictatorship and the current super-modern period, this paper argues that representations of otherness significantly influence current research agendas and understandings of identity well beyond the disappearance of the actual subjects described as others.     

The role of the methylation in the detoxication of arsenate in the rabbit

The biotransformation, tissue retention, intracellular binding and biokinetics of arsenic were studied in rabbits exposed to [74As]arsenate (0.4 mg As/kg body wt., i.v.). Inhibition of the methyltransferase activity by injection of periodate-oxidized adenosine (PAD) caused a marked decrease of the formation of [74As]dimethylarsinic acid (DMA), which gave rise to 1.5-4 times increased tissue levels of 74As. This is almost the same as reported for rabbits given arsenite in combination with PAD and was due to a rapid reduction of the arsenate to arsenite which bound to the tissues. Only about 30% of the arsenate given was excreted unchanged in the urine, indicating that a large part was reduced to AsIII. Thus the methylation to DMA seems to be almost as important for the detoxication following exposure to arsenate as that following exposure to arsenite. In the rabbits with normal methylating capacity 50-70% of the produced AsIII was methylated to DMA. The liver was the only organ in which DMA was present 1 h after the administration, indicating that this is the main site of the methylation. The DMA was rapidly cleared from all tissues except the thyroid.     

Changes in the functional organization of the respiratory system in residents of Western Siberia in the winter season

The respiratory parameters of healthy young men from Western Siberia have been examined. The correlations between the parameters have been analyzed, and the functional structure of the respiratory system in summer and winter has been identified. It has been found that different regulatory programs operate depending on the temperature of the inhaled air. The study has shown that the changes in the oxygen demand of the body in summer are mediated by the changes in the volume of pulmonary ventilation (“ventilation” or “summer program”). In winter, when maintaining the level of energy processes in the body is in conflict with maintaining thermal homeostasis in the respiratory regions of the lungs, pulmonary ventilation becomes limited, and the number of functioning lung units is reduced. At the same time, in compensation, the lung diffusion capacity increases (“diffusion” or “winter program”). This means that the functioning of the apparatus of external respiration is optimized in winter.