Second Locus of Bacteriophage P22 Necessary for the Maintenance of Lysogeny

A temperature-sensitive allele of a locus of phage P22, known to be involved in establishment of lysogeny, has been isolated. This mutant, P22 ts mnt, forms stable lysogens at 30 C which are induced by heating to 43 C. This shows that this locus is involved in the maintenance of lysogeny. The ts mnt locus is about 18 recombination units away from the c region. The wild allele, mnt⁺, is dominant over mnt and is responsible for a cytoplasmically diffusible product.     

UV sensitivity of a nonrepressor regulatory protein of bacteriophage P22.

The product of phage P22 gene c1 has two functions: it promotes synthesis of P22 repressor and it retards expression of some lytic genes. We present evidence that this product is inactivated in UV-irradiated hosts. The conditions for inactivation of c1 product include a functional DNA recombination system involving the host recA gene.     

High spatial resolution analysis of fungal cell biochemistry – bridging the analytical gap using synchrotron FTIR spectromicroscopy

Fungi impact humans and the environment in many ways, for good and ill. Some fungi support the growth of terrestrial plants or are used in biotechnology, and yet others are established or emerging pathogens. In some cases, the same organism may play different roles depending on the context or the circumstance. A better understanding of the relationship between fungal biochemical composition as related to the fungal growth environment is essential if we are to support or control their activities. Synchrotron FTIR (sFTIR) spectromicroscopy of fungal hyphae is a major new tool for exploring cell composition at a high spatial resolution. Brilliant synchrotron light is essential for this analysis due to the small size of fungal hyphae. sFTIR biochemical characterization of subcellular variation in hyphal composition will allow detailed exploration of fungal responses to experimental treatments and to environmental factors.     

Genetic contributions to precocity traits in racing Thoroughbreds

Adaptation to early training and racing (i.e. precocity), which is highly variable in racing Thoroughbreds, has implications for the selection and training of horses. We hypothesised that precocity in Thoroughbred racehorses is heritable. Age at first sprint training session (work day), age at first race and age at best race were used as phenotypes to quantify precocity. Using high‐density SNP array data, additive SNP heritability () was estimated to be 0.17, 0.14 and 0.17 for the three traits respectively. In genome‐wide association studies (GWAS) for age at first race and age at best race, a 1.98‐Mb region on equine chromosome 18 (ECA18) was identified. The most significant association was with the myostatin (MSTN) g.66493737C>T SNP (P = 5.46 × 10^?12 and P = 1.89 × 10^?14 respectively). In addition, two SNPs on ECA1 (g.37770220G>A and g.37770305T>C) within the first intron of the serotonin receptor gene HTR7 were significantly associated with age at first race and age at best race. Although no significant associations were identified for age at first work day, the MSTN:g.66493737C>T SNP was among the top 20 SNPs in the GWAS (P = 3.98 × 10^?5). Here we have identified variants with potential roles in early adaptation to training. Although there was an overlap in genes associated with precocity and distance aptitude (i.e. MSTN), the HTR7 variants were more strongly associated with precocity than with distance. Because HTR7 is closely related to the HTR1A gene, previously implicated in tractability in young Thoroughbreds, this suggests that behavioural traits may influence precocity.     

Late‐season snowfall is associated with decreased offspring survival in two migratory arctic‐breeding songbird species

While the effect of weather on reproduction has been studied for many years in avian taxa, the rapid pace of climate change in arctic regions has added urgency to this question by changing the weather conditions species experience during breeding. Given this, it is important to understand how factors such as temperature, rain, snowfall, and wind affect reproduction both directly and indirectly (e.g. through their effects on food availability). In this study, we ask how weather factors and food availability influence daily survival rates of clutches in two arctic‐breeding migratory songbirds: the Lapland longspur Calcarius lapponicus, a circumpolar breeder, and Gambel's white‐crowned sparrow Zonotrichia leucophrys gambelii, which breeds in shrubby habitats across tundra, boreal and continental climates. To do this, we monitored clutch survival in these two species from egg‐lay through fledge at field sites located near Toolik Field Station (North Slope, Alaska) across 5 yr (2012–2016). Our results indicate that snowfall and cold temperatures decreased offspring survival rates in both species; although Lapland longspurs were more susceptible to snowfall. Food availability, quantified by pitfall sampling and sweep‐net sampling methods, had minimal effects on offspring survival. Some climate models predict increased precipitation for the Arctic with global warming, and in the Toolik region, total snow accumulation may be increasing. Placed in this context, our results suggest that changes in snow storms with climate change could have substantial consequences for reproduction in migratory songbirds breeding in the North American Arctic.     

Health and chemical burdens of fish species from polluted and hyper-eutrophic freshwater ecosystems in South Africa

Three aquatic ecosystems in South Africa, the Hartbeespoort, Klipvoor and Bospoort Dams, are classified as hyper-eutrophic, because of high nutrient loads and chemical pollution. Water and two fish species, Clarias gariepinus and Cyprinus carpio, were collected from these dams to assess the impact of eutrophication and chemical pollutants on their health status. Water and muscle samples were analysed for organic and inorganic chemicals. Condition factor was determined and a necropsy performed to note any macroscopic abnormalities. A histology-based fish health assessment was done on the liver, kidney, gills and gonads. A number of fish from the three dams exhibited livers with fatty change and focal discoloration, skin lesions and parasites within the visceral cavity. The prevalence and severity of histopathology in the liver resulted in higher liver index values than the index values for kidneys and gills. Aluminium, silicon and chromium were detected in the water and muscle tissue. The DDT metabolite p,p’-DDE was present in both species, as well as in fish from the reference site, Marico-Bosveld Dam. Only C. gariepinus from Hartbeespoort Dam had p,p’-DDD levels higher than 5 µg g^?1 per edible portion. Water from hyper-eutrophic dams adversely affects the health of freshwater fish.