Regulation of the AbrA1/A2 Two-Component System in Streptomyces coelicolor and the Potential of Its Deletion Strain as a Heterologous Host for Antibiotic Production

The Two-Component System (TCS) AbrA1/A2 from Streptomyces coelicolor M145 is a negative regulator of antibiotic production and morphological differentiation. In this work we show that it is able to auto-regulate its expression, exerting a positive induction of its own operon promoter, and that its activation is dependent on the presence of iron. The overexpression of the abrA2 response regulator (RR) gene in the mutant ΔabrA1/A2 results in a toxic phenotype. The reason is an excess of phosphorylated AbrA2, as shown by phosphoablative and phosphomimetic AbrA2 mutants. Therefore, non-cognate histidine kinases (HKs) or small phospho-donors may be responsible for AbrA2 phosphorylation in vivo. The results suggest that in the parent strain S. coelicolor M145 the correct amount of phosphorylated AbrA2 is adjusted through the phosphorylation-dephosphorylation activity rate of the HK AbrA1. Furthermore, the ABC transporter system, which is part of the four-gene operon comprising AbrA1/A2, is necessary to de-repress antibiotic production in the TCS null mutant. Finally, in order to test the possible biotechnological applications of the ΔabrA1/A2 strain, we demonstrate that the production of the antitumoral antibiotic oviedomycin is duplicated in this strain as compared with the production obtained in the wild type, showing that this strain is a good host for heterologous antibiotic production. Thus, this genetically modified strain could be interesting for the biotechnology industry.     

Quantitative proteome analysis of detergent‐resistant membranes identifies the differential regulation of protein kinase C isoforms in apoptotic T cells

Several lines of evidence suggest that detergent‐resistant membranes (DRMs) (also known as lipid rafts and glycosphingolipid‐enriched microdomains) may have a role in signaling pathways of apoptosis. Here, we developed a method that combines DRMs isolation and methanol/chloroform extraction with stable isotope labeling with amino acids in cell culture‐based quantitative proteome analysis of DRMs from control and cisplatin‐induced apoptotic Jurkat T cells. This approach enabled us to enrich proteins with a pivotal role in cell signaling of which several were found with increased or decreased amounts in DRMs upon induction of apoptosis. Specifically, we show that three isoforms of protein kinase C (PKC) are regulated differently upon apoptosis. Although PKCα which belongs to the group of conventional PKCs is highly up‐regulated in DRMs, the levels of two novel PKCs, PKCη and PKCθ, are significantly reduced. These alterations/differences in PKC regulation are verified by immunoblotting and confocal microscopy. In addition, a specific enrichment of PKCα in apoptotic blebs and buds is shown. Furthermore, we observe an increased expression of ecto‐PKCα as a result of exposure to cisplatin using flow cytometry. Our results demonstrate that in‐depth proteomic analysis of DRMs provides a tool to study differential localization and regulation of signaling molecules important in health and disease.     

Complete Genome Sequence of the Naphthalene-Degrading Bacterium Pseudomonas stutzeri AN10 (CCUG 29243)

Pseudomonas stutzeri AN10 (CCUG 29243) can be considered a model strain for aerobic naphthalene degradation. We report the complete genome sequence of this bacterium. Its 4.71-Mb chromosome provides insights into other biodegradative capabilities of strain AN10 (i.e., benzoate catabolism) and suggests a high number of horizontal gene transfer events.     

Gender-Dependent Association of FTO Polymorphisms with Body Mass Index in Mexicans

To evaluate the associations between six single-nucleotide polymorphisms (SNPs) in intron 1 of FTO and body mass index (BMI), a case-control association study of 2314 unrelated Mexican-Mestizo adult subjects was performed. The association between each SNP and BMI was tested using logistic and linear regression adjusted for age, gender, and ancestry and assuming additive, recessive, and dominant effects of the minor allele. Association analysis after BMI stratification showed that all five FTO SNPs (rs1121980, rs17817449, rs3751812, rs9930506, and rs17817449), were significantly associated with obesity class II/III under an additive model (P<0.05). Interestingly, we also documented a genetic model-dependent influence of gender on the effect of FTO variants on increased BMI. Two SNPs were specifically associated in males under a dominant model, while the remainder were associated with females under additive and recessive models (P<0.05). The SNP rs9930506 showed the highest increased in obesity risk in females (odds ratio = 4.4). Linear regression using BMI as a continuous trait also revealed differential FTO SNP contributions. Homozygous individuals for the risk alleles of rs17817449, rs3751812, and rs9930506 were on average 2.18 kg/m² heavier than homozygous for the wild-type alleles; rs1121980 and rs8044769 showed significant but less-strong effects on BMI (1.54 kg/m² and 0.9 kg/m², respectively). Remarkably, rs9930506 also exhibited positive interactions with age and BMI in a gender-dependent manner. Women carrying the minor allele of this variant have a significant increase in BMI by year (0.42 kg/m², P = 1.17 x 10⁻¹⁰). Linear regression haplotype analysis under an additive model, confirmed that the TGTGC haplotype harboring all five minor alleles, increased the BMI of carriers by 2.36 kg/m² (P = 1.15 x 10⁻⁵). Our data suggest that FTO SNPs make differential contributions to obesity risk and support the hypothesis that gender differences in the mechanisms involving these variants may contribute to disease development.     

A rapid and simple method for constructing stable mutants of <Emphasis Type="Italic">Acinetobacter baumannii</Emphasis>

Background  

Acinetobacter baumannii is a multidrug-resistant bacterium responsible for nosocomial infections in hospitals worldwide. Study of mutant phenotypes is fundamental for understanding gene function. The methodologies developed to inactivate A. baumannii genes are complicated and time-consuming; sometimes result in unstable mutants, and do not enable construction of double (or more) gene knockout mutant strains of A. baumannii.     

Abundance patterns of the toxic phytoplankton in coastal waters of the Balearic Archipelago (NW Mediterranean Sea): a multivariate approach

The prevalence of catch-and-release factors known to adversely affect the mortality or physical condition of Australian bass Macquaria novemaculeata were surveyed across a range of anglers throughout impoundments and rivers in New South Wales. Subsamples of tournament-caught fish were also monitored in tanks for 1 h after being weighed to quantify immediate mortalities and sublethal physical damage. Most fish were caught on actively fished artificial baits, and were mouth hooked (96%), which resulted in no immediate mortality amongst monitored fish and a low frequency of mortality-causing factors in surveys. However, fish that were weighed-in during tournaments often had fin damage (52% of fish) and/or barotrauma (25% of fish, in impoundments only), and were held in live wells with poor water-quality. The prevalence of these sublethal effects varied considerably according to the specific seasons, locations, rules and procedures of each tournament; but could not be reliably attributed to any of the recorded catch-and-release variables (except for dissolved oxygen, which was significantly influenced by live-well volume). While these results validate the current release of angled Australian bass as a means of conserving their stocks, the potential for adverse effects could nevertheless be minimised via simple changes to conventional handling.     

蒙古中部湖泊之谷沉积岩-玄武岩共存的渐新世地层:蒙古-奥地利合作项目回顾(英文)

Taatsiin Gol和Taatsiin Tsagaan Nuur地区的渐新世沉积序列具有重要的地层学意义:这里出露的三达河组和Loh组沉积含有多个化石层和玄武岩夹层。在蒙古-奥地利合作项目中,从研究区域的33个剖面/化石地点的85个化石层中采集了289种化石(11种腹足类、2种两栖类、9种爬行类和267种哺乳类)。本文提供了所有地点的完整哺乳动物清单,并结合大、小哺乳动物的新资料,对蒙古非正式的生物带A,B,C和C1进行了更新。40Ar/39Ar测年给出了至少两组玄武岩年龄:早渐新世玄武岩I组大约31.5Ma,晚渐新世玄武岩II组大约28Ma。它们可以用作渐新世哺乳动物地层学的年代校正点。从早渐新世至晚渐新世,哺乳动物群发生了显著的变化,包括晚渐新世种数的明显减少。这种趋势在肉齿类、食肉类和反刍类中最为突出。     

Late Holocene palaeoecology of Lago Verde: evidence of human impact and climate change in the northern limit of the neotropics during the late formative and classic periods

Multiproxy analysis (pollen, diatom, charcoal) on a 6 m core from Lago Verde (Sierra de Los Tuxtlas), shows evidences of environmental changes and human impact on the evergreen rainforest on the tropical lowlands of eastern Mexico during the last ca. 2,800 years. Prehistoric human occupation is recorded since the late Formative throughout the middle Classic (250 b.c.–ca. a.d. 800) by the presence of maize pollen, a low abundance of tropical arboreal taxa and a high abundance of herbaceous pollen and charcoal particles. This occurred under a scenario of very low lake levels from which dry conditions are inferred based on the dominance of aerophilous and periphytic diatom taxa. After ca. a.d. 800 the site was abandoned and forest regeneration started, at the same time higher lake levels, an indication of more humid conditions, were established. In the absence of human disturbance, tropical forest regeneration was rapid (ca. 200 years). Fluctuations in pollen composition during times of low human population at the site are related to climate variability, with the highest tropical forest diversity and lake levels recorded during the Little Ice Age. Modern human impact is also recorded and compared with the prehistoric deforestation event. Comparison with palaeoecological records from Yucatan and the highlands of central Mexico offers a Mesoamerican perspective of climatic variability giving evidence that the late Formative and early to middle Classic demographic expansion occurred under a scenario of climates dryer than present, with the Postclassic characterized by moister conditions. The end of the Classic (ca. a.d. 800–1000) is identified as a period of rapid climate change which marks one of the most important cultural transitions in Mesoamerica.