Seasonal pattern in age, sex and body condition of Barn Owls Tyto alba killed on motorways

The Barn Owl Tyto alba was the most common owl killed on motorways in northeastern France. The possible causes of this mortality and the age, sex and body condition of the road-killed birds in 1991–1994 have been investigated. The number of birds killed on roads was highest in the period from early autumn to late winter, i.e. during the non-breeding period, and showed a pattern similar to that of the temporal difference between sunset, which varies with day length, and peak of traffic, the occurrence of which is constant throughout the year. An autumnal mortality peak, concomitant with the post-fledging dispersal, was mainly of immature birds, especially females. A second mortality peak in late winter was composed mainly of mature birds, with an equal proportion of males and females. From autumn to winter, there was no significant change in body mass in the different age and sex categories of birds killed on roads, except for mature males which had a significantly lower body mass in winter. From early autumn to late winter, the mean body mass of immature owls killed on motorways did not differ significantly from that of captive immatures fed ad libitum. This suggests that the immature birds were in good body condition. In contrast, the body mass of road-killed mature females was significantly lower than that of captive mature females over the same time periods. In mature males in late winter, a drop in body mass in both road-killed and captive birds suggests an endogenous seasonal phenomenon. Except for mature females, Barn Owls killed on roads in 1991–1994 were in good body condition. This does not support the idea that only birds in poor body condition were killed. We conclude that the mortality of Barn Owls on motorways in autumn and winter was probably related to the concomitance between the peak of traffic and the onset of hunting activity and the large number and dispersal of immature individuals during the same period.     

Evolution of spore release mechanisms in the saprolegniaceae (Oomycetes): evidence from a phylogenetic analysis of internal transcribed spacer sequences

Classical studies on spore release within the Saprolegniaceae (Oomycetes) led to the proposition that different mechanisms of sporangial emptying represent steps in an evolutionary transition series. We have reevaluated this idea in a phylogenetic framework using internal transcribed spacer sequences of four genera. These data were compared with the response to osmotic stress exhibited by each taxon. Saprolegnia emerges as the most basal genus, sister to Achlya, Thraustotheca, and Dictyuchus. Achlya and Thraustotheca are most closely related, while Dictyuchus appears to have evolved along a separate evolutionary lineage. The resulting phylogenetic framework is consistent with the idea that the mechanism of sporangial emptying exhibited by Saprolegnia represents the plesiomorphic condition from which the other mechanisms were derived independently. These alternative mechanisms of spore release may have resulted from a small number of mutations that inhibited axonemal development and altered the temporal and spatial expression of lytic enzymes that degrade the sporangial wall. Copyright 1998 Academic Press.     

Genetic analysis of the yopE region of Yersinia spp.: identification of a novel conserved locus, yerA, regulating yopE expression.

The yopE gene of Yersinia pseudotuberculosis was recently sequenced, and YopE was identified as an indispensable virulence determinant when tested in a mouse model (A. Forsberg and H. Wolf-Watz, Mol. Microbiol. 2:121-133, 1988). In the study described here, the DNA sequences of the yopE genes of Yersinia pestis EV76 and Yersinia enterocolitica 8081 were determined and compared with that of the Y. pseudotuberculosis gene. Only two codons were found to differ, both leading to amino acid replacements, when the gene from Y. pestis was compared. These two replacements were also present in the gene from Y. enterocolitica; in addition, 18 other codons were found to differ. Thirteen of these substitutions led to amino acid replacements. Downstream of the yopE gene, the plasmid partition locus par was found to be conserved in all three species. In Y. enterocolitica 8081, the sequence homology was interrupted by a putative insertion sequence element inserted between the yopE gene and the par region at a position only 5 base pairs downstream of the yopE stop codon. Upstream of the yopE gene, 620 base pairs were conserved in the three species. This region contained a 130-amino-acid-long open reading frame reading in the opposite direction to the yopE gene and expressed a 14-kilodalton protein in minicells. An insertion mutation in this region constructed in Y. pseudotuberculosis expressed significantly lower amounts of YopE protein in vitro than did the corresponding wild type. The expression level could be restored by transcomplementation. This new locus was designated yerA, for yopE-regulating gene A. The yerA mutant was avirulent when mice were challenged by oral infection.     

Piping Plover Chick Foraging,Growth, and Survival in the Great Plains

Abstract: We tested the hypothesis that piping plover (Charadrius melodus) habitat quality and chick survival on the Missouri River, USA, were lower on a cold-water reservoir and downstream from a hypolimnetic (cold-water) release dam with diel water fluctuations (Garrison Dam) than downstream from an epilimnetic dam (Gavins Point Dam). Plovers in adjacent alkali wetlands provided an index to the maximum reproductive potential in the region. Chicks gained weight more rapidly in the alkali wetlands than on epilimnetic and hypolimnetic river reaches. Invertebrate numbers and biomass were higher in the wetlands and epilimnetic reach, but chick survival was lower on the epilimnetic reach. Thus, piping plovers adapted to a variety of prey densities, and other factors, likely predation, reduced survival rates in the epilimnetic reach. Temporal and spatial variability in site quality indices suggests the need for a regional management strategy with different strategies at each site. Managers can minimize effects of local fluctuations in resource abundance and predators by ensuring protection of or creating geographically dispersed habitat. (JOURNAL OF WILDLIFE MANAGEMENT 72(3):682–687; 2008)     

siRNA, miRNA and HIV: promises and challenges

Small interfering RNA (siRNA) and microRNA (miRNA) are small RNAs of 18-25 nucleotides (nt) in length that play important roles in regulating gene expression. They are incorporated into an RNA-induced silencing complex (RISC) and serve as guides for silencing their corresponding target mRNAs based on complementary base-pairing. The promise of gene silencing has led many researchers to consider siRNA as an anti-viral tool. However, in long-term settings, many viruses appear to escape from this therapeutical strategy. An example of this may be seen in the case of human immunodeficiency virus type-1 (HIV-1) which is able to evade RNA silencing by either mutating the siRNA-targeted sequence or by encoding for a partial suppressor of RNAi (RNA interference). On the other hand, because miRNA targeting does not require absolute complementarity of base-pairing, mutational escape by viruses from miRNA-specified silencing may be more difficult to achieve. In this review, we discuss stratagems used by various viruses to avoid the cells' antiviral si/mi-RNA defenses and notions of how viruses might control and regulate host cell genes by encoding viral miRNAs (vmiRNAs).     

Exploiting polarity and chirality to probe the Hsp90 C-terminus

Inhibition of the Hsp90 C-terminus is an attractive therapeutic approach for the treatment of cancer. Novobiocin, the first Hsp90 C-terminal inhibitor identified, contains a synthetically complex noviose sugar that has limited the generation of structure-activity relationships for this region of the molecule. The work described herein utilizes various ring systems as noviose surrogates to explore the size and nature of the surrounding binding pocket.     

Characterization and overproduction of the Escherichia coli appA encoded bifunctional enzyme that exhibits both phytase and acid phosphatase activities

The appA gene that was previously shown to code for an acid phosphatase instead codes for a bifunctional enzyme exhibiting both acid phosphatase and phytase activities. The purified enzyme with a molecular mass of 44,708 Da was further separated by chromatofocusing into two isoforms of identical size with isoelectric points of 6.5 and 6.3. The isoforms had identical pH optima of 4.5 and were stable at pH values from 2 to 10. The temperature optimum for both phytase isoforms was 60 degrees C. When heated at different pH values the enzyme showed the greatest thermal resistance at pH 3. The pH 6.5 isoform exhibited K(m) and Vmax values of 0.79 mM and 3165 U.mg-1 of protein for phytase activity and 5.5 mM and 712 U.mg-1 of protein for acid phosphatase, respectively. The pH 6.3 isoform exhibited slightly lower K(m) and Vmax values. The enzyme exhibited similar properties to the phytase purified by Greiner et al. (1993), except the specific activity of the enzyme was at least 3.5-fold less than that previously reported, and the N-terminal amino acid sequence was different. The Bradford assay, which was used by Greiner et al. (1993) for determination of enzyme concentration was, in our hands, underestimating protein concentration by a factor of 14. Phytase production using the T7 polymerase expression system was enhanced by selection of a mutant able to grow in a chemically defined medium with lactose as the carbon source and inducer. Using this strain in fed-batch fermentation, phytase production was increased to over 600 U.mL-1. The properties of the phytase including the low pH optimum, protease resistance, and high activity, demonstrates that the enzyme is a good candidate for industrial production as a feed enzyme.     

Precipitation and Primary Health Care Visits for Gastrointestinal Illness in Gothenburg,Sweden

Background

The river Göta Älv is a source of freshwater for the City of Gothenburg, Sweden, and we recently identified a clear influence of upstream precipitation on concentrations of indicator bacteria in the river water, as well as an association with the daily number of phone calls to the nurse advice line related to acute gastrointestinal illnesses (AGI calls). This study aimed to examine visits to primary health-care centers owing to similar symptoms (AGI visits) in the same area, to explore associations with precipitation, and to compare variability in AGI visits and AGI calls.

Methods

We obtained data covering six years (2007–2012) of daily AGI visits and studied their association with prior precipitation (0–28 days) using a distributed lag nonlinear Poisson regression model, adjusting for seasonal patterns and covariates. In addition, we studied the effects of prolonged wet and dry weather on AGI visits. We analyzed lagged short-term relations between AGI visits and AGI calls, and we studied differences in their seasonal patterns using a binomial regression model.

Results

The study period saw a total of 17,030 AGI visits, and the number of daily visits decreased on days when precipitation occurred. However, prolonged wet weather was associated with an elevated number of AGI visits. Differences in seasonality patterns were observed between AGI visits and AGI calls, as visits were relatively less frequent during winter and relatively more frequent in August, and only weak short-term relations were found.

Conclusion

AGI visits and AGI calls seems to partly reflect different types of AGI illnesses, and the patients’ choice of medical contact (in-person visits versus phone calls) appears to depend on current weather conditions. An association between prolonged wet weather and increased AGI visits supports the hypothesis that the drinking water is related to an increased risk of AGI illnesses.     

Effect of ACTH (tetracosactide) on steroid hormone levels in the mare. Part A: effect in intact normal mares and mares with possible estrous related behavioral abnormalities

Ovariectomized mares and mares with inactive ovaries may show signs of estrus. The reason behind this phenomenon is not clear; however, steroid hormones of adrenal origin have been suggested. Moreover, aberrant adrenal hormone production has been implied as a reason why some intact mares may change behavior. In the present study, the effect of ACTH on plasma levels of cortisol, progesterone, androstenedione and testosterone was investigated in intact mares with normal estrous behavior ('controls', n=5) and intact mares that according to their owners showed deviant estrous behavior ('problem' mares, n=7). Blood samples were collected hourly from 12:00 h until 14:00 h the following day (half-hourly between 14:00 and 17:00 h) on two occasions (at two estruses), with saline or ACTH treatment (tetracosactide) at 14:00 h (saline treatment day or ACTH treatment day). ACTH treatment caused a significant increase in plasma levels of cortisol, progesterone, androstenedione and testosterone in all mares (P<0.05). An overall significant difference in cortisol response to ACTH was found (P<0.05), with 'problem' mares showing a significantly lower increase in cortisol levels 30 min to 3h post ACTH treatment (P<0.001). The 'problem' mares also showed a significantly higher increase than controls in progesterone levels in the same time period (P<0.05). The reason for the reduced adreno-cortical reactivity, with a low cortisol response to the ACTH treatment, in the 'problem' mares is unknown, but may indicate a difference in adrenal function as compared to control mares.