Importance of the signals provided by the buck for the success of the male effect in goats

Under temperate and subtropical latitudes, ewes and goats display a reproductive seasonal pattern and their sexual activity during the anestrous period can be stimulated and synchronized by the introduction of males in the group, which is called the "male effect". The response of females to the male effect in the middle of the anestrous season is weak or absent. This failure may be due to the inability of the female to respond to males, as a result of a refractoriness of the female to the male stimulus. But, it may also be due to a low quality stimulus provided by the male which is, as the females, in seasonal rest. We tested this latter hypothesis in seasonally inactive goats kept under subtropical conditions by comparing the use of males with their sexual behavior stimulated or not by photoperiodic treatments. Treated males were able to induce estrous activity of females during the whole anestrus season. We have also determined that previous separation of the males and continuous contact during teasing are not absolute requisites when active bucks are used. While odor from the male and its sexual behavior play a primary role in inducing ovulation, vocalizations appear to facilitate the display of the does' estrous. It remains to be determined to which extent these conclusions apply under temperate latitudes and with more seasonal breeds.     

Catalytic advantages provided by selenocysteine in methionine-S-sulfoxide reductases

Methionine sulfoxide reductases are key enzymes that repair oxidatively damaged proteins. Two distinct stereospecific enzyme families are responsible for this function: MsrA (methionine-S-sulfoxide reductase) and MsrB (methionine-R-sulfoxide reductase). In the present study, we identified multiple selenoprotein MsrA sequences in organisms from bacteria to animals. We characterized the selenocysteine (Sec)-containing Chlamydomonas MsrA and found that this protein exhibited 10-50-fold higher activity than either its cysteine (Cys) mutant form or the natural mouse Cys-containing MsrA, making this selenoenzyme the most efficient MsrA known. We also generated a selenoprotein form of mouse MsrA and found that the presence of Sec increased the activity of this enzyme when a resolving Cys was mutated in the protein. These data suggest that the presence of Sec improves the reduction of methionine sulfoxide by MsrAs. However, the oxidized selenoprotein could not always be efficiently reduced to regenerate the active enzyme. Overall, this study demonstrates that sporadically evolved Sec-containing forms of methionine sulfoxide reductases reflect catalytic advantages provided by Sec in these and likely other thiol-dependent oxidoreductases.     

Understanding the X chromosome inactivation cycle in mice: A comprehensive view provided by nuclear transfer

During mouse development, imprinted X chromosome inactivation (XCI) is observed in preimplantation embryos and is inherited to the placental lineage, whereas random XCI is initiated in the embryonic proper. Xist RNA, which triggers XCI, is expressed ectopically in cloned embryos produced by somatic cell nuclear transfer (SCNT). To understand these mechanisms, we undertook a large-scale nuclear transfer study using different donor cells throughout the life cycle. The Xist expression patterns in the reconstructed embryos suggested that the nature of imprinted XCI is the maternal Xist-repressing imprint established at the last stage of oogenesis. Contrary to the prevailing model, this maternal imprint is erased in both the embryonic and extraembryonic lineages. The lack of the Xist-repressing imprint in the postimplantation somatic cells clearly explains how the SCNT embryos undergo ectopic Xist expression. Our data provide a comprehensive view of the XCI cycle in mice, which is essential information for future investigations of XCI mechanisms.     

Nitrogen fixation in wheat provided by Klebsiella pneumoniae 342

In this report, all of the criteria necessary for the demonstration of nitrogen fixation in wheat (Triticum aestivum L.), the world's most important crop, are shown upon inoculation with a nitrogen-fixing bacterium, Klebsiella pneumoniae 342 (Kp342). Kp342 relieved nitrogen (N) deficiency symptoms and increased total N and N concentration in the plant. Nitrogen fixation was confirmed by 15N isotope dilution in the plant tissue and in a plant product, chlorophyll. All of these observations were in contrast to uninoculated plants, plants inoculated with a nitrogen-fixing mutant of Kp342, and plants inoculated with dead Kp342 cells. Nitrogenase reductase was produced by Kp342 in the intercellular space of the root cortex. Wild-type Kp342 and the nifH mutant colonized the interior of wheat roots in equal numbers on a fresh weight basis. The nitrogen fixation phenotype described here was specific to cv. Trenton. Inoculation of cvs. Russ or Stoa with Kp342 resulted in no relief of nitrogen deficiency symptoms.     

New insights into cancer-related proteins provided by the yeast model

Cancer is a devastating disease with a profound impact on society. In recent years, yeast has provided a valuable contribution with respect to uncovering the molecular mechanisms underlying this disease, allowing the identification of new targets and novel therapeutic opportunities. Indeed, several attributes make yeast an ideal model system for the study of human diseases. It combines a high level of conservation between its cellular processes and those of mammalian cells, with advantages such as a short generation time, ease of genetic manipulation and a wealth of experimental tools for genome- and proteome-wide analyses. Additionally, the heterologous expression of disease-causing proteins in yeast has been successfully used to gain an understanding of the functions of these proteins and also to provide clues about the mechanisms of disease progression. Yeast research performed in recent years has demonstrated the tremendous potential of this model system, especially with the validation of findings obtained with yeast in more physiologically relevant models. The present review covers the major aspects of the most recent developments in the yeast research area with respect to cancer. It summarizes our current knowledge on yeast as a cellular model for investigating the molecular mechanisms of action of the major cancer-related proteins that, even without yeast orthologues, still recapitulate in yeast some of the key aspects of this cellular pathology. Moreover, the most recent contributions of yeast genetics and high-throughput screening technologies that aim to identify some of the potential causes underpinning this disorder, as well as discover new therapeutic agents, are discussed.     

Factors affecting the resistance to heat transfer provided by clothing

1. 1. This paper discusses the factors that affect the insulation and evaporative resistance provided by clothing.

2. 2. These include: fabric thickness and density, the amount of body surface area covered by garments, the evenness of the distribution of fabrics over the body surface, the increase in surface area for heat loss due to clothing, the looseness or tightness of fit, a person's body position (seated vs standing), body motion and wind.

Brucella abortus synthesizes phosphatidylcholine from choline provided by the host

The Brucella cell envelope is characterized by the presence of phosphatidylcholine (PC), a common phospholipid in eukaryotes that is rare in prokaryotes. Studies on the composition of Brucella abortus 2308 phospholipids revealed that the synthesis of PC depends on the presence of choline in the culture medium, suggesting that the methylation biosynthetic pathway is not functional. Phospholipid composition of pmtA and pcs mutants indicated that in Brucella, PC synthesis occurs exclusively via the phosphatidylcholine synthase pathway. Transformation of Escherichia coli with an expression vector containing the B. abortus pcs homologue was sufficient for PC synthesis upon induction with IPTG (isopropyl-beta-d-thiogalactopyranoside), while no PC formation was detected when bacteria were transformed with a vector containing pmtA. These findings imply that Brucella depends on choline provided by the host cell to form PC. We could not detect any obvious associated phenotype in the PC-deficient strain under vegetative or intracellular growth conditions in macrophages. However, the pcs mutant strain displays a reproducible virulence defect in mice, which suggests that PC is necessary to sustain a chronic infection process.     

Cryoprotection provided by heat shock treatment in Saccharomyces cerevisiae.

Saccharomyces cerevisiae cells exposed to 43 degrees C (normal being 30 degrees C) exhibit the synthesis of heat shock proteins (hsps). Time course studies indicated that the major hsps (97 kDa, 85 kDa and 70 kDa family) are induced within 10 min. of heat shock and attain maximum amount with two hours of treatment. The viability of cells decreased by 99% when directly frozen into liquid nitrogen. However, a prior heat shock (2 hours) increased the cell survival by 20-30 fold. Such an effect of prior heat shock treatment could be supported by light and electron microscopical studies. Differential scanning calorimetric analysis of whole cells revealed that heat shock treatment decreases the denaturation (delta H) of total cellular proteins. A direct correlation between the degree of hsp inducibility and protection against freezing and thawing injury was observed. Cycloheximide treatment curtailed the synthesis of hsps as well as protection against subsequent freezing. This suggests that prior heat shock treatment protects the cells from freezing injury and, furthermore, that hsps can act as biological cryoprotectants.     

Estimation of the hypothermic component in neuroprotection provided by cannabinoids following cerebral ischemia

Cannabinoids have neuroprotective potentials, and the expression of endocannabinoids as well as cannabinoid receptors is induced after cerebral ischemia. They also induce hypothermia by lowering the hypothalamic set point. We have estimated the significance of such hypothermia in ischemic neuroprotection following systemic administration of WIN 55,212-2, a synthetic cannabinoid receptor agonist. Results showed that WIN 55,212-2 significantly reduced infarct volumes of rats subjected to focal cerebral ischemia (middle cerebral artery occlusion) and significantly decreased ischemic CA1 damage in rats subjected to global cerebral ischemia (two-vessel occlusion). A significant (approximately 50%) part of this neuroprotection was provided by WIN 55,212-2 induced hypothermia (33.7+/-1.1 degrees C/34.9+/-1.6 degrees C), because prevention of hypothermia by maintaining body core temperatures between 37.0 and 38.0 degrees C dissolved the neuroprotective effect into a hypothermic component and an unidentified component. Finally, the ability of WIN 55,212-2 to reduce levels of the proinflammatory cytokine IFNgamma in the infarcted hemisphere of rats subjected to focal cerebral ischemia required hypothermia. For the cannabinoid WIN 55,212-2, we have isolated and directly demonstrated that hypothermia is only part of, although significant, cannabinoid mediated neuroprotection in both global and focal cerebral ischemia. We conclude that cannabinoids are reliable candidates for drug-induced hypothermia and neuroprotection. These neuroprotective effects of cannabinoids could provide the basis for potential therapeutic uses of cannabinoids and/or endocannabinoids in stroke.     

The determination of huperzine A in European Lycopodiaceae species by HPLC-UV-MS

A rapid qualitative HPLC-UV-MS method was developed for the detection of huperzine A in Lycopodiaceae species. HPLC coupled with mass spectrometry experiments allowed the identification of the alkaloid and enabled targeted analysis of complex matrices such as herbal extracts. Huperzine A was detected by single ion monitoring of the pseudomolecular ion [M + H]+ at m/z 243.2. The alkaloid was also detected on TLC in a bioautographic enzyme assay with acetylcholinesterase to show the activity of the compound. Four Lycopodiaceae species collected in Switzerland were tested by these methods and Huperzia selago (L.) Bernh. ex Schrank et Martius was the only species found to contain huperzine A.     

Stabilization provided by neighboring strands is critical for the mechanical stability of proteins

Single-molecule force spectroscopy studies and steered molecular dynamics simulations have revealed that protein topology and pulling geometry play important roles in determining the mechanical stability of proteins. Most studies have focused on local interactions that are associated with the force-bearing β-strands. Interactions mediated by neighboring strands are often overlooked. Here we use Top7 and barstar as model systems to illustrate the critical importance of the stabilization effect provided by neighboring β-strands on the mechanical stability. Using single-molecule atomic force microscopy, we showed that Top7 and barstar, which have similar topology in their force-bearing region, exhibit vastly different mechanical-stability characteristics. Top7 is mechanically stable and unfolds at ∼150 pN, whereas barstar is mechanically labile and unfolds largely below 50 pN. Steered molecular dynamics simulations revealed that stretching force peels one force-bearing strand away from barstar to trigger unfolding, whereas Top7 unfolds via a substructure-sliding mechanism. This previously overlooked stabilization effect from neighboring β-strands is likely to be a general mechanism in protein mechanics and can serve as a guideline for the de novo design of proteins with significant mechanical stability and novel protein topology.     

Biological SOAP servers and web services provided by the public sequence data bank

A number of biological data resources (i.e. databases and data analytical tools) are searchable and usable on-line thanks to the internet and the World Wide Web (WWW) servers. The output from the web server is easy for us to browse. However, it is laborious and sometimes impossible for us to write a computer program that finds a useful data resource, sends a proper query and processes the output. It is a serious obstacle to the integration of distributed heterogeneous data resources. To solve the issue, we have implemented a SOAP (Simple Object Access Protocol) server and web services that provide a program-friendly interface. The web services are accessible at http://www.xml.nig.ac.jp/.