Abnormal production of interleukin (IL)-11 and IL-8 in polycythaemia vera

We studied the production of interleukin (IL)-11 and IL-8, two cytokines known to affect erythropoiesis, in polycythemia vera (PV). In vivo, IL-11 was detected more frequently in serum and bone marrow (BM) plasma of PV patients than in controls (healthy donors and patients with idiopathic erythrocytosis (IE)). In addition, serum IL-11 levels of PV patients were higher than those of controls. IL-8 was elevated in serum of both PV and IE patients (respective median levels: 38.6 and 242pg/ml, vs 4.4pg/ml for healthy donors). BM plasma IL-8 levels of PV patients (508pg/ml) were significantly higher than those of IE patients (120pg/ml). In vitro, bone marrow (BM) stromal cells (BMSC) of PV patients produced significantly more IL-11 (x6.4) and IL-8 (x8.3) than BMSC of healthy donors or IE patients. In conclusion, both IL-11 and IL-8 are overproduced in PV, apparently by BMSC; IL-8 is also overproduced in IE, by cells other than BMSC.     

Synergistic Population Density and Environmental Effects on Deer Body Condition

The ability to predict energy and protein allocation to different body condition parameters according to environmental constraints is a key component in understanding the processes underlying population dynamics. We investigated the influence of a proxy of population density and environmental factors on individual body condition parameters of female white-tailed deer (Odocoileus virginianus) based on long-term monitoring (2002–2013) of autumn harvest on Anticosti Island, Québec, Canada. We used dressed body mass, peroneus muscle mass, and rump fat thickness to evaluate the nutritional status of 3,123 adult females. Density index and winter precipitation negatively affected fat reserves in autumn. We detected the negative effect of winter precipitation on fat reserves only at low density likely because individuals at high density were already in bad condition. High normalized difference vegetation index (NDVI) in spring (May–Jun) reduced body mass, and this influence was more pronounced under high population density, probably because individuals at high densities were less likely to be buffered against environmental fluctuations when resources were scarcer than resources at low population density. Using different body condition parameters, our results provide additional insights on how northern ungulates influenced by food limitation may respond to future environmental changes. We recommend managers to collect long-term data on multiple physiological indicators of body condition. These data could be used as an index of ecological changes and provide a quantitative basis to help setting harvest objectives or supporting adaptive management. © 2020 The Wildlife Society.     

Exome Capture Reveals ZNF423 and CEP164 Mutations, Linking Renal Ciliopathies to DNA Damage Response Signaling

Nephronophthisis-related ciliopathies (NPHP-RC) are degenerative recessive diseases that affect kidney, retina, and brain. Genetic defects in NPHP gene products that localize to cilia and centrosomes defined them as "ciliopathies." However, disease mechanisms remain poorly understood. Here, we identify by whole-exome resequencing, mutations of MRE11, ZNF423, and CEP164 as causing NPHP-RC. All three genes function within the DNA damage response (DDR) pathway. We demonstrate that, upon induced DNA damage, the NPHP-RC proteins ZNF423, CEP164, and NPHP10 colocalize to nuclear foci positive for TIP60, known to activate ATM at sites?of DNA damage. We show that knockdown of CEP164 or ZNF423 causes sensitivity to DNA damaging agents and that cep164 knockdown in zebrafish results in dysregulated DDR and an NPHP-RC phenotype. Our findings link degenerative diseases of the kidney and retina, disorders of increasing prevalence, to mechanisms of DDR. PAPERFLICK:     

Host–microbe interactions as a driver of acclimation to salinity gradients in brown algal cultures

Like most eukaryotes, brown algae live in association with bacterial communities that frequently have beneficial effects on their development. Ectocarpus is a genus of small filamentous brown algae, which comprises a strain that has recently colonized freshwater, a rare transition in this lineage. We generated an inventory of bacteria in Ectocarpus cultures and examined the effect they have on acclimation to an environmental change, that is, the transition from seawater to freshwater medium. Our results demonstrate that Ectocarpus depends on bacteria for this transition: cultures that have been deprived of their associated microbiome do not survive a transfer to freshwater, but restoring their microflora also restores the capacity to acclimate to this change. Furthermore, the transition between the two culture media strongly affects the bacterial community composition. Examining a range of other closely related algal strains, we observed that the presence of two bacterial operational taxonomic units correlated significantly with an increase in low salinity tolerance of the algal culture. Despite differences in the community composition, no indications were found for functional differences in the bacterial metagenomes predicted to be associated with algae in the salinities tested, suggesting functional redundancy in the associated bacterial community. Our study provides an example of how microbial communities may impact the acclimation and physiological response of algae to different environments, and thus possibly act as facilitators of speciation. It paves the way for functional examinations of the underlying host–microbe interactions, both in controlled laboratory and natural conditions.     

High genetic diversity despite drastic bottleneck in a critically endangered,long‐lived seabird,the Mascarene Petrel Pseudobulweria aterrima

The Mascarene Petrel Pseudobulweria aterrima is a critically endangered seabird endemic to Reunion Island, with an extremely small population suffering several threats. Fifteen polymorphic microsatellite loci were isolated from this species to analyse genetic diversity, estimate contemporary effective population size, search for evidence of a population bottleneck and see whether results support the hypothesis that life history traits could preserve allelic diversity in small populations. Results from 22 individuals found grounded as a consequence of light pollution highlight a surprisingly high genetic diversity, an absence of inbreeding, a contemporary effective population size estimated at approximately 1211 individuals and a probable bottleneck around 10 000 generations ago. Additional studies on genetic diversity and structure from a larger number of samples are thus required to evaluate the evolutionary potential of this critically endangered species.     

High-throughput microsatellite isolation through 454 GS-FLX Titanium pyrosequencing of enriched DNA libraries

Microsatellites (or SSRs: simple sequence repeats) are among the most frequently used DNA markers in many areas of research. The use of microsatellite markers is limited by the difficulties involved in their de novo isolation from species for which no genomic resources are available. We describe here a high-throughput method for isolating microsatellite markers based on coupling multiplex microsatellite enrichment and next-generation sequencing on 454 GS-FLX Titanium platforms. The procedure was calibrated on a model species (Apis mellifera) and validated on 13 other species from various taxonomic groups (animals, plants and fungi), including taxa for which severe difficulties were previously encountered using traditional methods. We obtained from 11,497 to 34,483 sequences depending on the species and the number of detected microsatellite loci ranged from 199 to 5791. We thus demonstrated that this procedure can be readily and successfully applied to a large variety of taxonomic groups, at much lower cost than would have been possible with traditional protocols. This method is expected to speed up the acquisition of high-quality genetic markers for nonmodel organisms.     

THE BREEDING SEABIRDS OF TROMELIN ISLAND (WESTERN INDIAN OCEAN): POPULATION SIZES,TRENDS AND BREEDING PHENOLOGY

Le Corre, M. 1996. The breeding seabirds of Tromelin Island (western Indian Ocean): population sizes, trends and breeding phenology. Ostrich 67: 155–159.

Formerly six or eight species of seabirds bred on Tromelin Island, but currently only two species do so: The Redfooted Booby Sula sula and the Masked Booby S. dactylatra. The last two species which became locally extinct, the Lesser Frigatebird Fregata ariel and the Greater Frigatebird F. minor, probably stopped breeding on the island as a consequence of human disturbance to breeding colonies. The populations of the two species of booby have opposing trends since 1954. The Masked Booby's population increased from 60 pairs in 1954 to 200–250 pairs in 1996 while the Red-footed Booby's population decreased from 500 pairs in 1968 to 130–180 pairs in 1996. The impacts of human settlement, introduced brown rats Rattus norvegicus, local extinction of the Greater Frigatebird and other factors are discussed to explain these changes in population sizes. New data are provided on the breeding phenology of the two species of booby. Finally, the importance of this island for the conservation of seabirds in the western Indian Ocean is discussed.     

Lysine 335, part of the KMSKS signature sequence, plays a crucial role in the amino acid activation catalysed by the methionyl-tRNA synthetase from Escherichia coli.

The KMSKS pattern, conserved among several aminoacyl-tRNA synthetase sequences, was first recognized in the Escherichia coli methionyl-tRNA synthetase through affinity labelling with an oxidized reactive derivative of tRNA(Met)f. Upon complex formation, two lysine residues of the methionyl-tRNA synthetase (Lys61 and 335, the latter being part of the KMSKS sequence) could be crosslinked by the 3'-acceptor end of the oxidized tRNA. Identification of an equivalent reactive lysine residue at the active centre of tyrosyl-tRNA synthetase designated the KMSKS sequence as a putative component of the active site of methionyl-tRNA synthetase. To probe the functional role of the labelled lysine residue within the KMSKS pattern, two variants of methionyl-tRNA synthetase containing a glutamine residue at either position 61 or 335 were constructed by using site-directed mutagenesis. Substitution of Lys61 slightly affected the enzyme activity. In contrast, the enzyme activities were very sensitive to the substitution of Lys335 by Gln. Pre-steady-state analysis of methionyladenylate synthesis demonstrated that this substitution rendered the enzyme unable to stabilize the transition state complex in the methionine activation reaction. A similar effect was obtained upon substituting Lys335 by an alanine instead of a glutamine residue, thereby excluding an effect specific for the glutamine side-chain. Furthermore, the importance of the basic character of Lys335 was investigated by studying mutants with a glutamate or an arginine residue at this position. It is concluded that the N-6-amino group of Lys335 plays a crucial role in the activation of methionine, mainly by stabilizing the transient complex on the way to methionyladenylate, through interaction with the pyrophosphate moiety of bound ATP-Mg2+. We propose, therefore, that the KMSKS pattern in the structure of an aminoacyl-tRNA synthetase sequence represents a signature sequence characteristic of both the pyrophosphate subsite and the catalytic centre.