Characterization and pathogenic evaluation of Bacillus thuringiensis and Bacillus sphaericus isolates from Argentinean soils

Eighty soil samples of different origin (from urban, agricultural, forested and horticultural areas) which had not previously been treated with bioinsecticides, were collected and examined to investigate the presence of Bacillus thuringiensis and B. sphaericus. From a total of 1473 bacterial isolates examined by differential staining techniques and growth on nutrient agar with the addition of penicillin and streptomycin, 31 (2.1%) strains of Bacillus sphaericus and 25 (1.6%) strains of Bacillus thuringiensis were isolated. These strains were tested for their pathogenicity against Diptera (Culex quinquefasciatus) and Lepidoptera (Anticarsia gemmatalis and Spodoptera frugiperda). Seven strains of Bacillus thuringiensis subspecies kurstaki were found to be pathogenic to Spodoptera frugiperda and twenty-two strains showed a pathological effect against Anticarsia gemmatalis. None of the strains of Bacillus thuringiensis nor the Bacillus sphaericus investigated, showed pathogenic activity against Culex quinquefasciatus. The strains of Bacillus thuringiensis were characterized serologically as belonging to six serotypes (darmstadiensis, entomocidus, kurstaki, muju, sotto and xianguangiensis). One strain seemed to be a new serotype. The electrophoretic profiles of the strains of Bacillus thruringiensis showed bands of 130 kDa similar to those found in strains pathogenic against Lepidoptera. Some physicochemical characteristics were also studied in the soil samples, in order to relate them to the presence or absence of these Bacillus species.     

Association between dopamine and somatostatin receptor expression and pharmacological response to somatostatin analogues in acromegaly

Acromegaly is a hormonal disorder resulting from excessive growth hormone (GH) secretion frequently produced by pituitary adenomas and consequent increase in insulin‐like growth factor 1 (IGF‐I). Elevated GH and IGF‐I levels result in a wide range of somatic, cardiovascular, endocrine, metabolic and gastrointestinal morbidities. Somatostatin analogues (SSAs) form the basis of medical therapy for acromegaly and are currently used as first‐line treatment or as second‐line therapy in patients undergoing unsuccessful surgery. However, a considerable percentage of patients do not respond to SSAs treatment. Somatostatin receptors (SSTR1‐5) and dopamine receptors (DRD1‐5) subtypes play critical roles in the regulation of hormone secretion. These receptors are considered important pharmacological targets to inhibit hormone oversecretion. It has been proposed that decreased expression of SSTRs may be associated with poor response to SSAs. Here, we systematically examine SSTRs and DRDs expression in human somatotroph adenomas by quantitative PCR. We observed an association between the response to SSAs treatment and DRD4, DRD5, SSTR1 and SSTR2 expression. We also examined SSTR expression by immunohistochemistry and found that the immunohistochemical detection of SSTR2 in particular might be a good predictor of response to SSAs.     

Cell Survival during Complete Nutrient Deprivation Depends on Lipid Droplet-fueled β-Oxidation of Fatty Acids

Cells exposed to stress of different origins synthesize triacylglycerols and generate lipid droplets (LD), but the physiological relevance of this response is uncertain. Using complete nutrient deprivation of cells in culture as a simple model of stress, we have addressed whether LD biogenesis has a protective role in cells committed to die. Complete nutrient deprivation induced the biogenesis of LD in human LN18 glioblastoma and HeLa cells and also in CHO and rat primary astrocytes. In all cell types, death was associated with LD depletion and was accelerated by blocking LD biogenesis after pharmacological inhibition of Group IVA phospholipase A₂ (cPLA₂α) or down-regulation of ceramide kinase. Nutrient deprivation also induced β-oxidation of fatty acids that was sensitive to cPLA₂α inhibition, and cell survival in these conditions became strictly dependent on fatty acid catabolism. These results show that, during nutrient deprivation, cell viability is sustained by β-oxidation of fatty acids that requires biogenesis and mobilization of LD.     

Metabolic balance in colorectal cancer is maintained by optimal Wnt signaling levels

Wnt pathways are important for the modulation of tissue homeostasis, and their deregulation is linked to cancer development. Canonical Wnt signaling is hyperactivated in many human colorectal cancers due to genetic alterations of the negative Wnt regulator APC. However, the expression levels of Wnt‐dependent targets vary between tumors, and the mechanisms of carcinogenesis concomitant with this Wnt signaling dosage have not been understood. In this study, we integrate whole‐genome CRISPR/Cas9 screens with large‐scale multi‐omic data to delineate functional subtypes of cancer. We engineer APC loss‐of‐function mutations and thereby hyperactivate Wnt signaling in cells with low endogenous Wnt activity and find that the resulting engineered cells have an unfavorable metabolic equilibrium compared with cells which naturally acquired Wnt hyperactivation. We show that the dosage level of oncogenic Wnt hyperactivation impacts the metabolic equilibrium and the mitochondrial phenotype of a given cell type in a context‐dependent manner. These findings illustrate the impact of context‐dependent genetic interactions on cellular phenotypes of a central cancer driver mutation and expand our understanding of quantitative modulation of oncogenic signaling in tumorigenesis.     

石油泄漏对暴风海燕群体的短期影响

2002年11月原油泄漏前后,我们对伊比利亚半岛比斯开湾内的Aketx岛上的暴风海燕(Hydrobatespelagicus)进行了监测。1993 -2005年期间,利用雾网法调查了暴风海燕的数量,并通过直接观察法来统计雏鸟出飞率。在石油泄漏前,暴风海燕的种群数量亦存在年际波动,天气变化和食物丰盛度可能是引起这一现象的根本原因。在2003年,繁殖个体的身体条件较前些年差,繁殖对的数量和雏鸟成活率也有所下降。2004年繁殖对的数量明显少于2003年,繁殖个体的身体状况稍强于2003年,且所有卵都孵化成功。2005年的种群数量已经回升到石油泄漏前的水平,几乎所有配对的暴风海燕都能成功繁殖,亲鸟的身体条件也恢复到了石油泄漏前的水平。值得注意的是,这一群体中幼年个体的数量仍在减少,表明石油污染对种群数量的影响仍然存在,确定污染物在体内积累对这些海鸟所造成的影响将是下一步研究的重点。     

Inferring insect feeding patterns from sugar profiles: a comparison of statistical methods

1. Investigations in nutritional ecology often require the identification of animal feeding patterns in natural conditions (what, where, and when do animals eat). Thus, methods are needed to trace not only individual resource uptake but also the relative use of different resources in a population or community.
2. Recent biochemical developments allow predicting the use of sugar‐rich resources from insects in the field. Individual feeding status (feeding history, food sources) is inferred by comparing insect sugar profiles with those of individuals fed on controlled diets. Individual assignations are then used to predict the relative consumption of different resources at the population or community level. As both steps may generate error, accurate prediction rules are needed. However, research from other domains (e.g., protein‐marking studies) suggests that classical decision rules used for such tasks may sometimes induce bias.
3. This study evaluated the performance of these rules and compared them to alternative methods on simulated, realistic datasets. It tested different methods for individual classification but also introduced methods for prevalence estimation, whose specific purpose is to estimate the relative frequency of different classes.
4. Alternative methods substantially outperformed the traditional algorithms to predict insect individual feeding status and population class distribution (relative frequency of insects with different feeding status). This study provided a simple decision tool to choose a method according to dataset size, variance, and biochemical method used.
5. Alternative methods should increase prediction confidence in future studies. Such approaches should easily be generalized to a wider range of systems.