Evolution and functional diversification of fructose bisphosphate aldolase genes in photosynthetic marine diatoms

Diatoms and other chlorophyll-c containing, or chromalveolate, algae are among the most productive and diverse phytoplankton in the ocean. Evolutionarily, chlorophyll-c algae are linked through common, although not necessarily monophyletic, acquisition of plastid endosymbionts of red as well as most likely green algal origin. There is also strong evidence for a relatively high level of lineage-specific bacterial gene acquisition within chromalveolates. Therefore, analyses of gene content and derivation in chromalveolate taxa have indicated particularly diverse origins of their overall gene repertoire. As a single group of functionally related enzymes spanning two distinct gene families, fructose 1,6-bisphosphate aldolases (FBAs) illustrate the influence on core biochemical pathways of specific evolutionary associations among diatoms and other chromalveolates with various plastid-bearing and bacterial endosymbionts. Protein localization and activity, gene expression, and phylogenetic analyses indicate that the pennate diatom Phaeodactylum tricornutum contains five FBA genes with very little overall functional overlap. Three P. tricornutum FBAs, one class I and two class II, are plastid localized, and each appears to have a distinct evolutionary origin as well as function. Class I plastid FBA appears to have been acquired by chromalveolates from a red algal endosymbiont, whereas one copy of class II plastid FBA is likely to have originated from an ancient green algal endosymbiont. The other copy appears to be the result of a chromalveolate-specific gene duplication. Plastid FBA I and chromalveolate-specific class II plastid FBA are localized in the pyrenoid region of the chloroplast where they are associated with β-carbonic anhydrase, which is known to play a significant role in regulation of the diatom carbon concentrating mechanism. The two pyrenoid-associated FBAs are distinguished by contrasting gene expression profiles under nutrient limiting compared with optimal CO2 fixation conditions, suggestive of a distinct specialized function for each. Cytosolically localized FBAs in P. tricornutum likely play a role in glycolysis and cytoskeleton function and seem to have originated from the stramenopile host cell and from diatom-specific bacterial gene transfer, respectively.     

Ketoolivosyl-tetracenomycin C: a new ketosugar bearing tetracenomycin reveals new insight into the substrate flexibility of glycosyltransferase ElmGT

A new tetracenomycin analog, 8-demethyl-8-(4'-keto)-α-L-olivosyl-tetracenomycin C, was generated through combinatorial biosynthesis. Streptomyces lividans TK 24 (cos16F4) was used as a host for expression of a 'sugar plasmid' (pKOL) directing the biosynthesis of NDP-4-keto-L-olivose. This strain harbors all of the genes necessary for production of 8-demethyl-tetracenomycin C and the sugar flexible glycosyltransferase ElmGT. To the best of our knowledge, this report represents the first characterization of a tetracenomycin derivative decorated with a ketosugar moiety. Also, as far as we know, 4-keto-L-olivose has only been described as an intermediate of oleandomycin biosynthesis, but has not been described before as an appendage for a polyketide compound. Furthermore, this report gives further insight into the substrate flexibility of ElmGT to include an NDP-ketosugar, which is unusual and is rarely observed among glycosyltransferases from antibiotic biosynthetic pathways.     

Fitness of reciprocal F1 hybrids between Rhinanthus minor and Rhinanthus major under controlled conditions and in the field

The performance of first‐generation hybrids determines to a large extent the long‐term outcome of hybridization in natural populations. F₁ hybrids can facilitate further gene flow between the two parental species, especially in animal‐pollinated flowering plants. We studied the performance of reciprocal F₁ hybrids between Rhinanthus minor and R. major, two hemiparasitic, annual, self‐compatible plant species, from seed germination to seed production under controlled conditions and in the field. We sowed seeds with known ancestry outdoors before winter and followed the complete life cycle until plant death in July the following season. Germination under laboratory conditions was much lower for the F₁ hybrid formed on R. major compared with the reciprocal hybrid formed on R. minor, and this confirmed previous results from similar experiments. However, this difference was not found under field conditions, which seems to indicate that the experimental conditions used for germination in the laboratory are not representative for the germination behaviour of the hybrids under more natural conditions. The earlier interpretation that F₁ hybrid seeds formed on R. major face intrinsic genetic incompatibilities therefore appears to be incorrect. Both F₁ hybrids performed at least as well as and sometimes better than R. minor, which had a higher fitness than R. major in one of the two years in the greenhouse and in the field transplant experiment. The high fitness of the F₁ hybrids confirms findings from naturally mixed populations, where F₁ hybrids appear in the first year after the two species meet, which leads to extensive advanced‐hybrid formation and introgression in subsequent generations.     

Prevalence of Escherichia coli strains resistance to antibiotics in wound infections and raw milk

Antibiotic-resistant Escherichia coli strains including extended-spectrum β-lactamase (ESBL) isolates are globally widespread in medical, food, and environmental sources. Some of these strains are considered the most pathogenic bacteria in humans. The present work examined the predominance of antibiotic resistance in E. coli strains in wound infections comparing with E. coli strains isolated from a raw milk as a potential source of those strains. The wound infections included abdomen, anus, arm, back, buttock, chest, foot, hand, head, leg, lung, mouth, neck, penis, thigh, toe, and vagina infections. In total, 161 and 153 isolates identified as E. coli were obtained from wound infections and raw milk, respectively. A Vitek 2 system innovated by bioMérieux, France was applied to perform the identification and susceptibility tests. The E. coli isolates that have ability to produce ESBL were detected by an ESBL panel and NO45 card (bioMérieux). Over half of the E. coli were from abdomen, back, and buttock wound infections. More than 50%of the E. coli isolates obtained from wound infections were resistant to cefazolin, ampicillin, cefuroxime, ciprofloxacin, mezlocillin, moxifloxacin, piperacillin, and tetracycline; 70% of the isolates from wound infections and 0% of the isolates from raw milk were E. coli isolates produced ESBL. The data showed that the strains resistance to multi-antibiotic and produced ESBL are more widespread among wound infections than in raw milk.     

Antihyperlipidemic and antioxidant effects of feather protein hydrolysate in high‐fat diet‐fed mice

The hyperlipidemia is a serious health problem that increases the risk of many complications including cardiovascular disease. This study aims to evaluate the possible antihyperlipidemic effects of the feather protein hydrolysate (FPH) in a mice fed with a high‐fat diet (HFD)‐fed mice during 5 weeks. The FPH administration improved dose‐dependent lipid profile, as well as the liver and renal dysfunction indices in hyperlipidemic mice. The FPH also restored the antioxidant status in liver, kidney, and heart by lowering the lipid peroxidation and enhancing the antioxidant enzymes (catalase (CAT), glutathione peroxidase (GPx) and superoxide dismutase [SOD]). Moreover, the histological studies proved that FPH administration prevents hepatic steatosis, glomerular hyperfiltration risk, and cardiac muscle hypertrophy. Accordingly, the FPH is a promising novel medicinal ingredient for possible use in the hyperlipidemic treatment and related complications.     

Effects of Dietary Supplementation of Probiotic Mix and Prebiotic on Growth Performance,Cecal Microbiota Composition,and Protection Against Escherichia coli O78 in Broiler Chickens

Probiotics and Antimicrobial Proteins - The current study conducted to investigate the effects of a multi-strain commercial probiotic mix and prebiotic (isomaltooligosaccharide, IMO) on broiler...     

Vesicular traffic at the cell membrane regulates oocyte meiotic arrest

Vertebrate oocytes are maintained in meiotic arrest for prolonged periods of time before undergoing oocyte maturation in preparation for fertilization. Cyclic AMP (cAMP) signaling plays a crucial role in maintaining meiotic arrest, which is released by a species-specific hormonal signal. Evidence in both frog and mouse argues that meiotic arrest is maintained by a constitutively active G-protein coupled receptor (GPCR) leading to high cAMP levels. Because activated GPCRs are typically targeted for endocytosis as part of the signal desensitization pathway, we were interested in determining the role of trafficking at the cell membrane in maintaining meiotic arrest. Here we show that blocking exocytosis, using a dominant-negative SNAP25 mutant in Xenopus oocytes, releases meiotic arrest independently of progesterone. Oocyte maturation in response to the exocytic block induces the MAPK and Cdc25C signaling cascades, leading to MPF activation, germinal vesicle breakdown and arrest at metaphase of meiosis II with a normal bipolar spindle. It thus replicates all tested aspects of physiological maturation. Furthermore, inhibiting clathrin-mediated endocytosis hinders the effectiveness of progesterone in releasing meiotic arrest. These data show that vesicular traffic at the cell membrane is crucial in maintaining meiotic arrest in vertebrates, and support the argument for active recycling of a constitutively active GPCR at the cell membrane.     

Effect of Some Nitrosative Agents on the Growth of <Emphasis Type="Italic">vgb</Emphasis>-bearing <Emphasis Type="Italic">Enterobacter aerogenes</Emphasis> Strains

The effect of transnitrosation intermediate between S-nitroso-N-acetylcysteine (NACysNO) and cysteine on the growth of vgb-bearing Enterobacter aerogenes was investigated using three parameters: the ratio of the specific growth rates, the inhibition zone, and α-amylase synthesis for the culture exposed to stressors to that of the same stressor-free cultures. The effect of NACysNO/cysteine on the growth of Enterobacter strains was distinctive as compared with the CysNO, NACysNO, and their combination. At a higher concentration (2 mM), the extents of inhibition based on the μ_{NACysNO/cysteine}/μ_{no stress} ratio for these cultures were 57%, 62%, and 68% for VHb-expressing, parental, and pUC9-harboring cells, respectively. The inhibition caused by 2 mM NACysNO in the presence of 1 mM cysteine in all bacterial strains was almost twofold that achieved by NACysNO alone. Based on the diameter of the inhibition zone and α-amylase productivity, the four compounds (NACysNO/Cysteine, CysNO, NACysNO, and their combinations) affected the E. aerogenes strains in a concentration-dependent and negative manner. This negative effect was lower in vgb-bearing than vgb-lacking strains. Thus, sulfur-to-sulfur transnitrosation was an efficient NO release and significantly (P < 0.05) affects the growth of Enterobacter strains, to a lesser extent in vgb-bearing strains.