Steroid control of longevity in Drosophila melanogaster

Ecdysone, the major steroid hormone of Drosophila melanogaster, is known for its role in development and reproduction. Flies that are heterozygous for mutations of the ecdysone receptor exhibit increases in life-span and resistance to various stresses, with no apparent deficit in fertility or activity. A mutant involved in the biosynthesis of ecdysone displays similar effects, which are suppressed by feeding ecdysone to the flies. These observations demonstrate the importance of the ecdysone hormonal pathway, a new player in regulating longevity.     

Postprandial kinetics of gene expression of proteins involved in the digestive process in rainbow trout (<Emphasis Type="Italic">O. mykiss</Emphasis>) and impact of diet composition

The impact of increased incorporation of plant ingredients on diets for rainbow trout was evaluated in terms of gene expression of gastric (gastric lipase, pepsinogen) and intestinal (prolidase, maltase, phospholipase A2) digestive enzymes and nutrient transporters (peptide and glucose transporters), as well as of postprandial levels of plasma glucose, triglycerides and total free amino acids. For that purpose, trout alevins were fed from the start of exogenous feeding one of three different experimental diets: a diet rich in fish meal and fish oil (FM–FO), a plant-based diet (noFM–noFO) totally free from fish meal and fish oil, but containing plant ingredients and a Mixed diet (Mixed) intermediate between the FM–FO and noFM–noFO diets. After 16 months of rearing, all fish were left unfed for 72 h and then given a single meal to satiation. Blood, stomach and anterior intestine were sampled before the meal and at 2, 6 and 12 h after this meal. The postprandial kinetics of gene expression of gastric and intestinal digestive enzymes and nutrient transporters were then followed in trout fed the FM–FO diet. The postprandial profiles showed that the expression of almost all genes studied was stimulated by the presence of nutrients in the digestive tract of trout, but the timing (appearance of peaks) varied between genes. Based on these data, we have focused on the molecular response to dietary factors in the stomach and the intestine at 6 and 12 h after feeding, respectively. The reduction in FM and FO levels of dietary incorporation induced a significant decrease in the gene expression of gastric lipase, GLUT2 and PEPT1. The plasma glucose and triglycerides levels were also reduced in trout fed the noFM–noFO diet. Consequently, the present study suggests a decrease in digestive capacities in trout fed a diet rich in plant ingredients.     

The Endo-α(1,3)-Fucoidanase Mef2 Releases Uniquely Branched Oligosaccharides from Saccharina latissima Fucoidans

Fucoidans are complex bioactive sulfated fucosyl-polysaccharides primarily found in brown macroalgae. Endo-fucoidanases catalyze the specific hydrolysis of α-L-fucosyl linkages in fucoidans and can be utilized to tailor-make fucoidan oligosaccharides and elucidate new structural details of fucoidans. In this study, an endo-α(1,3)-fucoidanase encoding gene, Mef2, from the marine bacterium Muricauda eckloniae, was cloned, and the Mef2 protein was functionally characterized. Based on the primary sequence, Mef2 was suggested to belong to the glycosyl hydrolase family 107 (GH107) in the Carbohydrate Active enZyme database (CAZy). The Mef2 fucoidanase showed maximal activity at pH 8 and 35 °C, although it could tolerate temperatures up to 50 °C. Ca²⁺ was shown to increase the melting temperature from 38 to 44 °C and was furthermore required for optimal activity of Mef2. The substrate specificity of Mef2 was investigated, and Fourier transform infrared spectroscopy (FTIR) was used to determine the enzymatic activity (Units per μM enzyme: U_f/μM) of Mef2 on two structurally different fucoidans, showing an activity of 1.2 × 10⁻³ U_f/μM and 3.6 × 10⁻³ U_f/μM on fucoidans from Fucus evanescens and Saccharina latissima, respectively. Interestingly, Mef2 was identified as the first described fucoidanase active on fucoidans from S. latissima. The fucoidan oligosaccharides released by Mef2 consisted of a backbone of α(1,3)-linked fucosyl residues with unique and novel α(1,4)-linked fucosyl branches, not previously identified in fucoidans from S. latissima.     

Lulworthinone: In Vitro Mode of Action Investigation of an Antibacterial Dimeric Naphthopyrone Isolated from a Marine Fungus

Treatment options for infections caused by antimicrobial-resistant bacteria are rendered ineffective, and drug alternatives are needed—either from new chemical classes or drugs with new modes of action. Historically, natural products have been important contributors to drug discovery. In a recent study, the dimeric naphthopyrone lulworthinone produced by an obligate marine fungus in the family Lulworthiaceae was discovered. The observed potent antibacterial activity against Gram-positive bacteria, including several clinical methicillin-resistant Staphylococcus aureus (MRSA) isolates, prompted this follow-up mode of action investigation. This paper aimed to characterize the antibacterial mode of action (MOA) of lulworthinone by combining in vitro assays, NMR experiments and microscopy. The results point to a MOA targeting the bacterial membrane, leading to improper cell division. Treatment with lulworthinone induced an upregulation of genes responding to cell envelope stress in Bacillus subtilis. Analysis of the membrane integrity and membrane potential indicated that lulworthinone targets the bacterial membrane without destroying it. This was supported by NMR experiments using artificial lipid bilayers. Fluorescence microscopy revealed that lulworthinone affects cell morphology and impedes the localization of the cell division protein FtsZ. Surface plasmon resonance and dynamic light scattering assays showed that this activity is linked with the compound‘s ability to form colloidal aggregates. Antibacterial agents acting at cell membranes are of special interest, as the development of bacterial resistance to such compounds is deemed more difficult to occur.     

Genetic differentiation and gene flow in Colletotrichum sublineolum in Ethiopia,the centre of origin and diversity of sorghum,as revealed by AFLP analysis

Isolates of Colletotrichum sublineolum were collected from different sorghum‐producing regions of Ethiopia and divided into five groups based on their geographic origin. The growth rate of 50 isolates showed considerable variation: 1·7–5·8 mm day^?1, mean 3·3 mm day^?1. However, the isolates displayed little variation in colony colour and colony margin, except for isolates from the north, which were different from the others. Amplified fragment length polymorphism analysis of 102 isolates revealed much greater variations among the different groups. Dice similarity coefficients ranged from 0·32 to 0·96 (mean 0·78). Cluster analysis and principal coordinate analysis revealed a differentiation of the isolates according to their geographic origin, and both methods clearly indicated a genetic separation between the southern, the eastern and the other isolates. Analysis of molecular variance (amova ) indicated a high level of genetic variation both among (42%) and within (58%) the C. sublineolum sampling sites in Ethiopia. The amova also indicated a high level of genetic differentiation (F_ST = 0·42) and limited gene flow (Nm = 0·343). The results of this study confirmed the presence of a highly diverse pathogen, which is in agreement with the existence of diverse host genotypes and widely ranging environmental conditions in sorghum‐producing regions of the country. Such diversity should be taken into account in future breeding programmes to achieve an effective and sustainable disease management strategy.     

The status and need for characterization of Nordic animal genetic resources

ABSTRACT

The Nordic countries are committed to conserving farm animal genetic diversity. National reports on phenotypic and genetic characterization point towards a lack of characterization for many Nordic native breeds. Little to no knowledge on the traits of the animals and their derived products leads to potential remaining untapped. The objective of this study was to provide a quantitative assessment of phenotypic and genetic characterization of Nordic native breeds, through a literature search and obtaining census data. Six species and a total of 85 breeds were included. Studies were classified according to six different categories of characterization. Results showed that a large percentage of the breeds are not characterized at all. Moreover, most breeds have extremely low census sizes. A substantial effort to increase population sizes and document characteristics of Nordic native breeds, to promote conservation and sustainable use, is needed.     

Impact of microarthropod biomass on the composition of the soil fauna community and ecosystem processes

The effect of soil organisms on ecosystem processes strongly depends on the composition of the overall community. Community composition however undergoes constant shifts due to pronounced spatio-temporal patterns in biomass and abundance of individual fauna groups. On this background the present experiment aimed to assess the potential impacts of shifts in the biomass of a dominant soil fauna group (microarthropods) on total community composition and on ecosystem processes mediated by fauna or microbes (e.g. decomposition, nitrogen mineralization).Microcosms, filled with spruce litter, hosted soil fauna communities that either contained ambient microarthropod biomass (control) or two elevated levels of microarthropod biomass (1.5 and 2 fold increase), while initial microbial biomass and that of other faunal groups remained unaltered. After an incubation period of 2 months, the biomass of microorganisms and fauna groups as well as ecosystem process variables were determined.The increase in microarthropod biomass at the investigated levels induced changes in the faunal community; mainly via negative or positive feeding interactions between microarthropods and the affected animal groups (Enchytraeidae, Nematoda). The abundance and activity of microorganisms at lower trophic levels however remained unaffected by these alterations; buffering the effect of shifts in the community structure on ecosystem processes.     

玉米秸秆湿氧化预处理同步糖化发酵酒精

为了找到适合的玉米秸秆生产酒精工艺,该文采用碱性湿氧化预处理（195℃,15 min,Na2CO3 2 g/L,O2 1 200 kPa）与同步糖化发酵对玉米秸秆制备酒精进行了研究。结果表明：经过预处理,90%纤维素保留在固体中,回收率为95.87%。固体部分利用纤维素酶处理,在50℃ 24 h酶解率达到了67.6%。底物8%（质量分数）,经过142 h同步糖化发酵,酒精产量达到了理论酒精产量的79.0%。假定五碳糖和六碳糖都能够被利用,相当于1 t玉米秸秆能够产生262.7 kg的酒精。发酵过程中没有明显的抑制作用。该文为玉米秸秆发酵生产酒精提供了试验数据。