Identification of an Acinetobacter baumannii gene region with sequence and organizational similarity to Tn2670.

A chloramphenicol resistance gene was cloned from chromosomal DNA prepared from a clinical Acinetobacter baumannii isolate. Sequence analysis of this gene (cat) and the flanking DNA regions shows that this gene is linked to Tn21 and to IS1 in a manner similar to that found in Tn2670.     

Skin maculae,chronic diarrhea,cachexia, and splenomegaly—Late presentation of the first autochthonous case of visceral leishmaniasis in Tanzania

A 20-year-old man from Simanjiro district in northern Tanzania presented with a 3-year history of splenomegaly, fatigue, cachexia, skin maculae, and recent onset of watery diarrhea at Kilimanjaro Christian Medical Centre (KCMC) in Northern Tanzania. Due to laboratory findings of pancytopenia, diagnostic workup included bone marrow aspiration cytology and biopsy. Although the rapid test (IT LEISH, rK39 RDT) was negative, blood smear showed amastigote forms of leishmaniasis in macrophages. Repeat bone marrow aspiration and PCR eventually confirmed visceral leishmaniasis (VL). The patient denied travel to known endemic areas of VL. Treatment was initiated with Amphotericin B, but the patient died on the fourth day of treatment from respiratory insufficiency. An autopsy revealed massive organ manifestations of VL. This is the first reported autochthonous case of VL in Tanzania. Clark and colleagues detected the vector Phlebotomus martini in Northern Tanzania in 2013, in a region bordering the district of our patient. The negative rapid test draws attention to the fact that sensitivity and specificity were found to be low in East African VL patients as displayed earlier by a Kenyan study. Therefore, tissue samples (spleen or bone marrow) remain necessary for diagnosis. The variety of symptoms in this presented case was remarkable, including the occurrence of post-kala-azar dermal leishmaniasis (PKDL) and VL at the same time. This has been described in East African VL cases before as well as the occurrence of chronic diarrhea. An elongated undiagnosed period likely led to a mixed clinical picture that included hepato-splenomegaly, PKDL, cachexia, and diarrhea.     

Glucocorticoid signaling in pancreatic islets modulates gene regulatory programs and genetic risk of type 2 diabetes

Glucocorticoids are key regulators of glucose homeostasis and pancreatic islet function, but the gene regulatory programs driving responses to glucocorticoid signaling in islets and the contribution of these programs to diabetes risk are unknown. In this study we used ATAC-seq and RNA-seq to map chromatin accessibility and gene expression from eleven primary human islet samples cultured in vitro with the glucocorticoid dexamethasone at multiple doses and durations. We identified thousands of accessible chromatin sites and genes with significant changes in activity in response to glucocorticoids. Chromatin sites up-regulated in glucocorticoid signaling were prominently enriched for glucocorticoid receptor binding sites and up-regulated genes were enriched for ion transport and lipid metabolism, whereas down-regulated chromatin sites and genes were enriched for inflammatory, stress response and proliferative processes. Genetic variants associated with glucose levels and T2D risk were enriched in glucocorticoid-responsive chromatin sites, including fine-mapped variants at 51 known signals. Among fine-mapped variants in glucocorticoid-responsive chromatin, a likely casual variant at the 2p21 locus had glucocorticoid-dependent allelic effects on beta cell enhancer activity and affected SIX2 and SIX3 expression. Our results provide a comprehensive map of islet regulatory programs in response to glucocorticoids through which we uncover a role for islet glucocorticoid signaling in mediating genetic risk of T2D.     

Human ecology and the albedo effect in an arid environment

The results of a comparison of agricultural settlement and land-use and local precipitation patterns in the arid region of the Arava in Israel indicated that as the number of settlements and the area of cultivated land has increased since the 1950s, the albedo effect in the region has decreased, and the amounts of precipitation at the first October rains have increased. It is suggested that the albedo effect in desert areas is influenced by extended agricultural land-use.     

A mutation in gene CNGA3 is associated with day blindness in sheep

Lambs with congenital day blindness show diminished cone function, which is characteristic of achromatopsia, a congenital disorder described in humans and dogs. To identify gene(s) associated with sheep day blindness, we investigated mutations in the CNGA3, CNGB3, and GNAT2 genes which have been associated with achromatopsia. Sequencing the coding regions of those genes from four affected and eight non-affected lambs showed that all affected lambs were homozygous for a mutation in the CNGA3 gene that changes amino acid R236 to a stop codon. By PCR-RFLP-based testing, homozygosity for the stop codon mutation was detected in another 19 affected lambs. Non-affected individuals (n = 386) were non-carriers or heterozygous for the mutation. While a selection program has been launched to eradicate the day blindness mutation from Improved Awassi flocks, a breeding nucleus of day-blind sheep has been established to serve as animal models for studying human achromatopsia.     

Are we missing half of the viruses in the ocean?

Viruses are abundant in the ocean and a major driving force in plankton ecology and evolution. It has been assumed that most of the viruses in seawater contain DNA and infect bacteria, but RNA-containing viruses in the ocean, which almost exclusively infect eukaryotes, have never been quantified. We compared the total mass of RNA and DNA in the viral fraction harvested from seawater and using data on the mass of nucleic acid per RNA- or DNA-containing virion, estimated the abundances of each. Our data suggest that the abundance of RNA viruses rivaled or exceeded that of DNA viruses in samples of coastal seawater. The dominant RNA viruses in the samples were marine picorna-like viruses, which have small genomes and are at or below the detection limit of common fluorescence-based counting methods. If our results are typical, this means that counts of viruses and the rate measurements that depend on them, such as viral production, are significantly underestimated by current practices. As these RNA viruses infect eukaryotes, our data imply that protists contribute more to marine viral dynamics than one might expect based on their relatively low abundance. This conclusion is a departure from the prevailing view of viruses in the ocean, but is consistent with earlier theoretical predictions.