Mutations in the WRN gene in mice accelerate mortality in a p53-null background

Werner's syndrome (WS) is a human disease with manifestations resembling premature aging. The gene defective in WS, WRN, encodes a DNA helicase. Here, we describe the generation of mice bearing a mutation that eliminates expression of the C terminus of the helicase domain of the WRN protein. Mutant mice are born at the expected Mendelian frequency and do not show any overt histological signs of accelerated senescence. These mice are capable of living beyond 2 years of age. Cells from these animals do not show elevated susceptibility to the genotoxins camptothecin or 4-NQO. However, mutant fibroblasts senesce approximately one passage earlier than controls. Importantly, WRN(-/-);p53(-/-) mice show an increased mortality rate relative to WRN(+/-);p53(-/-) animals. We consider possible models for the synergy between p53 and WRN mutations for the determination of life span.     

Habitat alteration and the conservation of African primates: case study of Kibale National Park, Uganda

Tropical forests and the animals they support are being threatened by accelerating rates of forest conversion and degradation. In a continually fluctuating sociopolitical world, it is often impossible to protect areas from such conversion until the political environment is suitable to pursue conservation goals, by which time, the forests have often been converted to other uses. This reality suggests a need for inquiry into which primate species can persist after different types of disturbances and how quickly primate communities can recover from disturbance. Here we examine the persistence of primate populations in disturbed habitats by providing a case study of patterns of primate abundance in areas of Kibale National Park (766 km2), Uganda, that have been modified by different types and intensities of human activities, primarily commercial logging and agricultural clearing. Distributional surveys at 24 sites and detailed line-transect censuses at six sites demonstrate that primate populations in Kibale are often high and suggest that patterns of population change associated with disturbance are complex. Analysis of the land use coverage of Kibale reveals that abandoned farms (10.3%) and degraded forest (8.7%) now cover 146 km2. Unfortunately, we do not know what proportion of the farms were established on areas that were forest versus grassland. However, if the areas that are now abandoned farms were all once forested, this means that 79 km2 of forest has been lost. Based on density estimates from nearby sites, this would represent a loss of 52,612 monkeys and 200 chimpanzees. Populations would also have been affected by the degradation of the 66 km2 (8.7%) of forest. These estimates of the potential reductions in the primate populations that could have resulted from forest clearing and degradation illustrate the importance of protecting land. A review of the literature illustrates that the biomass of primates found within Kibale is very high in comparison to other locations and thus illustrates the importance of Kibale to regional conservation.     

Genetic variation of volatiles and rosmarinic acid in populations of Salvia fruticosa mill growing in Crete

Using plant material collected from the field and subsequently cultivated in the glasshouse, the basis of variation in a number of chemical parameters observed in Salvia fruticosa has been examined. It was shown that clones from three populations collected from different parts of Crete and previously found to exhibit different essential oil yields and profiles maintained these differences during cultivation. They were found to differ also in morphology and habit, phenolic yield and composition and different nitrogen-utilizing capacity as estimated by nitrate reductase activity. Some clones had very high levels of rosmarinic acid. The population with the highest essential oil yield had the lowest phenolic content and vice versa, but within populations there were clones with high levels of both.     

Sambunigrin and cyanogenic variability in populations of Sambucus canadensis L. (Caprifoliaceae)

The presence or absence of cyanogenic glycosides was determined for individuals from nine populations of Sambucus canadensis L. (elderberry) of east-central Illinois. In most of the populations tested, all or most of the individuals did not produce these compounds, in one, all were cyanogenic, whereas in another population this trait was highly variable. Addition of the enzyme emulsin to negative tests did not result in any further release of cyanide. The glycoside responsible is (S)-sambunigrin.     

Statistical analysis of yeast genomic downstream sequences reveals putative polyadenylation signals

The study of a few genes has permitted the identification of three elements that constitute a yeast polyadenylation signal: the efficiency element (EE), the positioning element and the actual site for cleavage and polyadenylation. In this paper we perform an analysis of oligonucleotide composition on the sequences located downstream of the stop codon of all yeast genes. Several oligonucleotide families appear over-represented with a high significance (referred to herein as ‘words’). The family with the highest over-representation includes the oligonucleotides shown experimentally to play a role as EEs. The word with the highest score is TATATA, followed, among others, by a series of single-nucleotide variants (TATGTA, TACATA, TAAATA . . .) and one-letter shifts (ATATAT). A position analysis reveals that those words have a high preference to be in 3′ flanks of yeast genes and there they have a very uneven distribution, with a marked peak around 35 bp after the stop codon. Of the predicted ORFs, 85% show one or more of those sequences. Similar results were obtained using a data set of EST sequences. Other clusters of over-represented words are also detected, namely T- and A-rich signals. Using these results and previously known data we propose a general model for the 3′ trailers of yeast mRNAs.     

Analysis of HPC1, HPCX, and PCaP in Icelandic hereditary prostate cancer

Putative prostate cancer susceptibility loci have recently been identified by genetic linkage analysis on chromosomes 1q24-25 (HPC1). 1q44.243 (PCaP), and Xq27-28 (HPCX). In order to estimate the genetic linkage in Icelandic prostate cancer families, we genotyped 241 samples from 87 families with eleven markers in the HPC1 region, six markers at PCaP, and eight at HPCX. Concurrently, we assessed allelic imbalance at the HPC1 and PCaP loci in selected tumors from the patients. For each of the candidate regions, the combined parametric and non-parametric LOD scores were strongly negative. Evidence for linkage allowing for genetic heterogeneity was also insignificant for all the regions. The results were negative irrespective of whether calculations were performed for the whole material or for a selected set of early age at onset families. The prevalence of allelic imbalance was relatively low in both the HPC1 (0%-9%) and PCaP (5%-20%) regions and was not elevated in tumors from positively linked families. Our studies indicate that the putative cancer susceptibility genes at chromosomes 1q24-25, 1q44.2-43, and Xq27-28 are unlikely to contribute significantly to hereditary prostate cancer in Iceland and that selective loss of the HPC1 and PCaP loci is a relatively rare somatic event in prostate cancers.     

Leptin, but not immune function, is linked to reproductive responsiveness to photoperiod

Energetic demands are high while energy availability is minimum during winter. To cope with this energetic bottleneck, animals exhibit numerous energy-conserving adaptations during winter, including changes in immune and reproductive functions. A majority of individual rodents within a population inhibits reproductive function (responders) as winter approaches. A substantial proportion of small rodents within a species, however, fails to inhibit reproduction (nonresponders) during winter in the field or in the laboratory when maintained in winter-simulated day lengths. In contrast, immune function is bolstered by short day lengths in some species. The specific mechanisms that link reproductive and immune functions remain unspecified. Leptin is a hormone produced by adipose tissue, and several studies suggest that leptin modulates reproductive and immune functions. The present study sought to determine if photoperiodic alterations in reproductive function and leptin concentrations are linked to photoperiod-modulated changes in immune function. Siberian hamsters (Phodopus sungorus) were housed in either long (LD 16:8) or short (LD 8:16) day lengths for 9 wk. After 9 wk, blood samples were collected during the middle of the light and dark phase to assess leptin concentrations. One week later, animals were injected with keyhole limpet hemocyanin to evaluate humoral immunity. Body mass, body fat content, and serum leptin concentrations were correlated with reproductive responsiveness to photoperiod; short-day animals with regressed gonads exhibited a reduction in these measures, whereas short-day nonresponders resembled long-day animals. In contrast, immune function was influenced by photoperiod but not reproductive status. Taken together, these data suggest that humoral immune function in Siberian hamsters is independent of photoperiod-mediated changes in leptin concentrations.     

Characterization of INTA 51-3, a New Atypical Strain of Bacillus thuringiensis from Argentina

Several isolates of Bacillus thuringiensis native to Argentina obtained in a nationwide screening program showed atypical crystal morphology. One of these strains, INTA 51-3, was further characterized in order to determine other features like protein composition of its parasporal crystal, plasmid pattern, identification of cry genes and toxicological properties. B. thuringiensis INTA 51-3 (serovar tohokuensis) had an amorphous inclusion containing a major protein component of ca. 130 kDa. After trypsin digestion of solubilized crystals, SDS-PAGE resolved a unique protease-resistant peptide of ca. 90 kDa. The plasmid pattern from INTA 51-3 resembled that of the standard strain HD-1. However, Southern analysis showed no hybridization to fragments of cry1Aa, cry2Aa, cry3A, and cry11A genes. Degenerate primers were used for identification of the cry1 genes by PCR. Nevertheless, the presence of cry1 type gene(s) in B. thuringiensis INTA 51-3 was confirmed. Highly concentrated crystal suspensions showed to be weakly toxic only to lepidopteran species. Received: 23 May 2000 / Accepted: 26 June 2000     

Effect of intracerebroventricular alpha-MSH on food intake, adiposity, c-Fos induction, and neuropeptide expression

alpha-Melanocyte-stimulating hormone (alpha-MSH) is a hypothalamic neuropeptide proposed to play a key role in energy homeostasis. To investigate the behavioral, metabolic, and hypothalamic responses to chronic central alpha-MSH administration, alpha-MSH was infused continuously into the third cerebral ventricle of rats for 6 days. Chronic alpha-MSH infusion reduced cumulative food intake by 10.7% (P < 0.05 vs. saline) and body weight by 4.3% (P < 0.01 vs. saline), which in turn lowered plasma insulin levels by 29.3% (P < 0.05 vs. saline). However, alpha-MSH did not cause adipose-specific wasting nor did it alter hypothalamic neuropeptide mRNA levels. Central alpha-MSH infusion acutely activated neurons in forebrain areas such as the hypothalamic paraventricular nucleus, as measured by a 254% increase in c-Fos-like immunoreactivity (P < 0.01 vs. saline), as well as satiety pathways in the hindbrain. Our findings suggest that, although an increase of central melanocortin receptor signaling acutely reduces food intake and body weight, its anorectic potency wanes during chronic infusion and causes only a modest decrease of body weight.