Does FSH signaling have a gender?

FSH is the main endocrine control of mammalian reproduction. FSH triggers somatic cells of the gonads which support germ cells metabolically, i.e. Sertoli cells of the seminiferous tubules, and granulosa cells harboring the oocyte, within the ovarian follicle. FSH leads to similar biological responses in both cell types since it stimulates proliferation and differentiation, according to the developmental stage. However, FSH receptor knock-out female mice are infertile, unlike male mice. Hence, FSH is not equally important in both sexes. Nevertheless, does FSH induce distinct signalling mechanisms in its target cells ? Here, we compare the signalling mechanisms induced by FSH in ovarian and testicular physiology.     

Does zoo herpetology have a future?

Fifty-two North American zoo reptile and amphibian departments were surveyed to determine their contributions to recognized American Zoo and Aquarium Association (AZA)-sponsored programs and formalized research projects over the past 10 years. Surveys also requested information concerning the allocation of resources for conservation and research programs, staff educational background, and entry level salaries. Twenty-two institutions responded to the survey, collectively indicating a total of 164 technical papers, 16 field studies, and 101 non-technical articles completed between 1987 and 1997. Of the 164 technical papers published, 130 (79%) were contributed by three institutions. Of the 16 field studies, seven were outside the United States, whereas nine focused on native species and ecosystems. Six of the reported field studies involved only financial or logistical support. Of the 101 non-technical articles, 42 (42%) were contributed by a single institution. Twenty-one formalized in-house research projects were reported. However, only four appeared to have a clearly defined objective. Survey respondents also reported nine species of reptiles and one amphibian taxon are managed by Species Survival Plans (SSPs). There are currently 12 Taxon Advisory Group (TAG) coordinators, with four of the current coordinators having served on multiple TAG committees. There are 41 AZA-approved studbooks for reptiles and two for amphibians, with 29 having actually been published to date. The average starting salary reported in our survey for entry level keeper positions was $19,500 (range, $13,500–30,000). The average level of education reported was high school graduate. There was no correlation between productivity and higher wages, or level of education. Only one institution received funding specifically for research. We conclude that zoo herpetology departments are not realizing their potential for formalized research and conservation projects and propose recommendations for future involvement. Zoo Biol 17:453–462, 1998. © 1998 Wiley-Liss, Inc.     

Does melanopsin bistability have physiological consequences?

Recent publications in the Journal of Biological Rhythms have focused on the hypothesis that the property of melanopsin bistability is functionally translated to in vivo mammalian physiology. Physiological consequences of photopigment bistability likely can be inferred from the more extensive invertebrate literature. In invertebrates, photopigment bistability results in (a) photoreceptor independence from specialized chromophore regenerating systems, (b) long-wavelength enhancement of a blue light effect, (c) expression of a prolonged depolarization after potential following intense blue light stimulation,and (d) photopigment endocytosis following chronic short-wavelength light exposure. If analogous physiological phenomena result from melanopsin bistability in mammals, then one can take advantage of the spectral composition of a light source to modulate its impact on photoentrainment and other light-dependent circadian phenomena. In any event,investigators studying phenomena that are affected by photic stimulation of intrinsically photosensitive retinal ganglion cells should detail the spectral composition of their light sources before, during, and after an experimental photic stimulus.     

Does my mouse have Alzheimer's disease?

Small animal models that manifest many of the characteristic neuropathological and behavioral features of Alzheimer's disease (AD) have been developed and have proven of great value for studying the pathogenesis of this disorder at the molecular, cellular and behavioral levels. The great progress made in our understanding of the genetic factors that either cause or contribute to the risk of developing AD has prompted many laboratories to create transgenic (tg) mice that overexpress specific genes which cause familial forms of the disease. Several of these tg mice display neuropathological and behavioral features of AD including amyloid β-peptide (Aβ) and amyloid deposits, neuritic plaques, gliosis, synaptic alterations and signs of neurodegeneration as well as memory impairment. Despite these similarities, important differences in neuropathology and behavior between these tg mouse models and AD have also been observed, and to date no perfect animal model has emerged. Moreover, ascertaining which elements of the neuropathological and behavioral phenotype of these various strains of tg mice are relevant to that observed in AD continues to be a challenge. Here we provide a critical review of the AD-like neuropathology and behavioral phenotypes of several well-known and utilized tg mice that express human APP transgenes.     

Does population ecology have general laws?

There is a widespread opinion among ecologists that ecology lacks general laws. In this paper the author argues that this opinion is mistaken. Taking the case of population dynamics, the author points out that there are several very general law-like propositions that provide the theoretical basis for most population dynamics models that were developed to address specific issues. Some of these foundational principles, like the law of exponential growth, are logically very similar to certain law of physics (Newton's law of intertia, for example, is almost a direct analogue of exponential growth). The author discusses two other principles (population self-limitation and resource-consumer oscillations), as well as the more elementary postulates that underlie them. None of the "laws" that the author proposes for population ecology are new. Collectively ecologists have been using these general principles in guiding development of their models and experiments since the days of Lotka, Volterra, and Gause.     

Does the tumor microenvironment influence radiation-induced apoptosis?

Cytotoxic anti-cancer agents induce apoptosis in tumor and normal tissues. Therefore, it is important to investigate which factors determine these apoptotic processes and hence their likely impact on therapeutic gain. Radiation-induced apoptosis in tumors may be inhibited due to mutations of apoptotic elements or to tumor microenvironmental conditions arising from vascular insufficiency. Tumors typically contain regions of hypoxia, low glucose and acidosis. Hypoxic cells compromise treatment partly because of reduced fixation of damage during radiotherapy and partly because they promote a more malignant phenotype. There is also evidence that hypoxia may inhibit apoptosis. For some cell types, concurrent hypoxia may modulate radiation-induced apoptosis while, for others, post-irradiation hypoxia may be required. This may reflect the activity of different apoptotic pathways. Pathways involving mitochondrial components as well as regulation of SAPK and Fas have been implicated. In addition, several key stages in apoptosis are sensitive to depletion of cellular energy reserves, which results from hypoxia and low glucose conditions. There is also evidence that low pH in tumors can interfere with radiation-induced apoptosis, partly through cell cycle arrest and other undefined mechanisms. Conclusions: Hypoxia, low glucose and acidosis influence radiation-induced apoptosis and thus may be detrimental to radiotherapy.     

Which alkylglycerols from shark liver oil have anti-tumour activities?

Alkylglycerols (alkyl-Gro) are ether lipids abundant in shark liver oil (SLO), and oral SLO or alkyl-Gro mix from this source have several in vivo biological activities including stimulation of haematopoiesis an immunological defences, or anti-tumour and anti-metastasis activities in vivo. Composition of natural alkyl-Gro mix contains several alkyl-Gro varying by chain length and unsaturation, and individual anti-tumour activity of each molecule present in natural mix remained unknown. We synthesized six prominent constituents of natural alkyl-Gro mix, namely 12:0, 14:0 16:0, 18:0, 16:1 n-7, and 18:1 n-9 alkyl-Gro. Using an in vivo model of grafted tumour in mice (3LL cells), we studied and compared the oral anti-tumour and anti-metastasis activities of each of these 6 alkyl-Gro. 16:1 and 18:1 alkyl-Gro showed strong activity in reducing lung metastasis number, while saturated alkyl-Gro had weaker (16:0) or no (12:0, 14:0, 18:0) effect. Spleen weights at day 20 after graft were also measured and showed tremendous variations depending on the treatment. Tumour graft resulted in a raise in spleen weight in control group, this raise was nearly abolished in 16:1 and 18:1 alkyl-Gro-treated mice, and was reduced in 14:0 and 16:0 alkyl-Gro-treated mice. Conversely, 18:0 alkyl-Gro-treated mice showed spleen weigh raise as compared with untreated grafted mice. These new data demonstrate a prominent role of unsaturation in the anti-tumour activities of alkyl-Gro.     

Does codon bias have an evolutionary origin?

Background  

There is a 3-fold redundancy in the Genetic Code; most amino acids are encoded by more than one codon. These synonymous codons are not used equally; there is a Codon Usage Bias (CUB). This article will provide novel information about the origin and evolution of this bias.     

Does New Guinea cannibalism have nutritional value?

This paper examines the question of the nutritional value of cannibalism. Although other authors have concluded that the practice does not have such value, we argue that this cannot properly be determined except in the context of the total subsistence economy and local human ecology. The paper also presents a format for the empirical investigation of foodgetting and new ethnographic information about New Guinea cannibalism. Our major conclusion is that this practice does have nutritional value for certain human groups, specifically tropical peoples living at lowmedium population densities and exploiting a diverse range of animal foods.     

Does human attractin have DP4 activity?

Mutations in the mouse ATRN gene, which encodes attractin, offer links between this protein and pigmentation, metabolism, immune status and neurodegeneration. However, the mechanisms of attractin action are not understood. The protein was first identified in humans in a circulating form in serum. A protease activity was postulated similar to the membrane-bound ectoenzyme DP4/CD26. In the last decade, both DP4/CD26 and attractin were controversially described to be the major source of human serum DP4 activity. We purified attractin from human plasma, and found that the DP4-like activity of the preparation shows nearly identical kinetic properties to that of recombinant human DP4. In contrast, the native electrophoretic behavior of this activity is clearly different from human and porcine DP4, but co-migrates with the protein band identified as attractin by Western blotting and N-terminal sequencing. Nevertheless, a DP4 impurity could be demonstrated in purified plasma attractin and the activity could be removed by ADA affinity chromatography, resulting in a homogenous attractin preparation without DP4 activity. These results are substantiated by expression of different attractin isoforms, in which no DP4 activity was found either. This indicates that the multidomain protein attractin acts as a receptor or adhesion protein rather than a protease.     

CD95 ligand--death factor and costimulatory molecule?

The CD95 ligand is involved as a death factor in the regulation of activation-induced cell death, establishment of immune privilege and tumor cell survival. In addition, CD95L may serve as a costimulatory molecule for T-cell activation. Alterations in expression or shedding of membrane and soluble CD95L are associated with numerous diseases, and underscore the pathophysiological relevance of the CD95/CD95L system. In most cases, the causal link between altered CD95L expression and pathophysiology is unknown. Given the potency of the molecule to regulate death and survival of many different cell types, the control of CD95L production, transport, storage, shedding and inactivation is of tremendous biological and clinical interest. This review summarizes the current knowledge, hypotheses and controversies about CD95L as a multifunctional ligand and receptor. It considers the different roles of membrane and soluble forms of CD95L and the complex networks of intracellular dynamics of protein trafficking, as well as the potential bidirectional signal transduction capacity of CD95L, with a focus on molecular interactions that have been worked out over the past years.     

Does carnitine have a role in fat absorption?

The effect of D-carnitine and tetradecylglycidic acid (TDGA), an inhibitor of carnitine palmitoyltransferase, on intestinal absorption of palmitic acid was determined. The proximal intestinal segment was ligated in adult male rats and filled with 0.5 microCi of 14C-palmitic acid alone or with either D-carnitine or TDGA. Thirty minutes later the radioactivity was determined in the intestinal lumen, intestinal wall and plasma. The absorption of palmitic acid was decreased in the presence of D-carnitine (10 mg/ml) as evidenced by significantly lower levels of radioactivity in the gut wall and the plasma and by significantly greater residual radioactivity in the lumenal contents. L-carnitine had no effect on plasma radioactivity but if D- and L-carnitine were given together the effect of D-carnitine was still in evidence. TDGA also inhibited intestinal absorption of palmitic acid.     

Does stromal interaction molecule-1 have five senses?

A single calcium (Ca²⁺) binding site within the canonical EF-hand loop was thought to govern the stromal interaction molecule-1 (STIM1) structural changes that lead to activation of Orai1 Ca²⁺ channels. Recent work by Gudlur et al., published in Nat Commun [9(1):4536], suggests that the STIM1 endoplasmic reticulum (ER) luminal domain has ∼5 additional Ca²⁺ binding sites, which underlie a surprising new proposal for Ca²⁺ sensing.