Purification and some catalytic properties of phosphoglucomutase from maize leaves

Phosphoglucomutase (EC 2.7.5.1, PGM) was purified to homogeneity from maize (Zea mays L.) leaves. The enzyme had specific activity 11. 7 U/mg protein and molecular mass (determined by gel-chromatography) of 133 +/- 4 kD. The molecular mass of PGM subunits determined by SDS-electrophoresis was 66 +/- 3 kD. The enzyme had Km for glucose-1-phosphate and glucose-1,6-diphosphate of 20.0 +/- 0.9 and 16.0 +/- 0.8 &mgr;M, respectively. Concentrations of glucose-1-phosphate and glucose-1,6-diphosphate above 3 and 0.4 mM, respectively, cause substrate inhibition. The enzyme activity was maximal at pH 8.0 and temperature 35 degreesC. Magnesium ions activate the enzyme and manganese ions inhibit it. 3-Phosphoglycerate is an uncompetitive inhibitor of the enzyme (Ki = 1.22 +/- 0.05 mM). Fructose-6-phosphate, 6-phosphogluconate, and ADP activate PGM, whereas ATP, UTP, and AMP inhibit the enzyme. Citrate was also a potent inhibitor, inhibitory effects of isocitrate and cis-aconitate being less pronounced.     

Hypertrophic cardiomyopathy in young Maine Coon cats caused by the p.A31P cMyBP-C mutation - the clinical significance of having the mutation

Background  

In Maine Coon (MC) cats the c.91G > C mutation in the gene MYBPC3, coding for cardiac myosin binding protein C (cMyBP-C), is associated with feline hypertrophic cardiomyopathy (fHCM). The mutation causes a substitution of an alanine for a proline at residue 31 (p.A31P) of cMyBP-C. The pattern of inheritance has been considered autosomal dominant based on a single pedigree. However, larger studies are needed to establish the significance of cats being heterozygous or homozygous for the mutation with respect to echocardiographic indices and the probability of developing fHCM. The objective of the present study was to establish the clinical significance of being homozygous or heterozygous for the p.A31P cMyBP-C mutation in young to middle-aged cats.     

Human platelet-rich plasma- and extracellular matrix-derived peptides promote impaired cutaneous wound healing in vivo

Previous work in our laboratory has described several pro-angiogenic short peptides derived from endothelial extracellular matrices degraded by bacterial collagenase. Here we tested whether these peptides could stimulate wound healing in vivo. Our experiments demonstrated that a peptide created as combination of fragments of tenascin X and fibrillin 1 (comb1) applied into cranial dermal wounds created in mice treated with cyclophosphamide to impair wound healing, can improve the rate of wound closure. Furthermore, we identify and characterize a novel peptide (UN3) created and modified from two naturally-occurring peptides, which are present in human platelet-rich plasma. In vitro testing of UN3 demonstrates that it causes a 50% increase in endothelial proliferation, 250% increase in angiogenic response and a tripling of epithelial cell migration in response to injury. Results of in vivo experiments where comb1 and UN3 peptides were added together to cranial wounds in cyclophosphamide-treated mice leads to improvement of wound vascularization as shown by an increase of the number of blood vessels present in the wound beds. Application of the peptides markedly promotes cellular responses to injury and essentially restores wound healing dynamics to those of normal, acute wounds in the absence of cyclophosphamide impairment. Our current work is aimed at understanding the mechanisms underlying the stimulatory effects of these peptides as well as identification of the cellular receptors mediating these effects.     

高温油藏内源微生物及其提高采收率潜力研究

大港孔店油田油藏特征、流体和微生物性质分析结果表明,属于高温生态环境,地层水矿化度较低,氮、磷浓度低,而且缺乏电子受体,主要的有机物来源是油气.油田采用经过除油处理的油藏产出水回注方式开发,油层中存在的微生物类型主要是厌氧嗜热菌,包括发酵菌(102个/mL～105个/mL),产甲烷菌(103个/mL);好氧菌主要存在于注水井周围.硫酸盐还原菌(SRB)还原速率0.002 μg S2-/(L·d)～18.9 μg S2-/(L·d),产甲烷菌产甲烷速率0.012 μgCH4/(L·d)～16.2 μgCH4/(L·d).好氧菌能够氧化油形成生物质,部分氧化产物为挥发性脂肪酸和表面活性荆.产甲烷菌在油氧化菌液体培养基中产生CH4,CO2为好氧微生物和厌氧微生物的共同代谢产物.这些产物具有提高原油流动性的作用.用示踪剂研究了注入水渗流方向.通过综合分析,油藏微生物具有较大的潜力,基于激活油层茵的提高采收率方法在该油田是可行的.     

Mycotoxigenic infestation in samples of cereal straw from Bihar, India

A survey of different types of cereal straw samples viz. paddy, maize and wheat, from Bihar State, India, was conducted in order to examine the mould flora and mycotoxin contamination. Out of 170 samples examined for mould flora,Aspergillus flavus group of fungi had highest level of incidence followed byA niger. Isolates ofA flavus, A ochraceus, Fusarium verticillioides andPenicillium citrinum were screened for their mycotoxins producing abilities. Out of 75, 63 and 68 isolates ofA flavus group obtained from stored straw of paddy, maize and wheat samples, respectively, 27 (36%), 14 (22%) and 24 (35%) were found to be toxigenic which produced different combinations of aflatoxins in different concentrations. The percentage toxigenicity was comparatively lower in the isolates of other mycotoxigenic fungi from all types of samples. Out of 222 samples of straw analysed for natural occurrence of different mycotoxins, besides the aflatoxins present, zearalenone, ochratoxin A and citrinin were also recorded alone or as co-contaminants. A conducive climate together with the socioeconomic conditions of this region are important determinants for the high incidence of mycotoxins in cereal straw samples.     

Mannitol in six autotrophic stramenopiles and Micromonas

Mannitol plays a central role in brown algal physiology since it represents an important pathway used to store photoassimilate. Several specific enzymes are directly involved in the synthesis and recycling of mannitol, altogether forming the mannitol cycle. The recent analysis of algal genomes has allowed tracing back the origin of this cycle in brown seaweeds to a horizontal gene transfer from bacteria, and furthermore suggested a subsequent transfer to the green micro-alga Micromonas. Interestingly, genes of the mannitol cycle were not found in any of the currently sequenced diatoms, but were recently discovered in pelagophytes and dictyochophytes. In this study, we quantified the mannitol content in a number of ochrophytes (autotrophic stramenopiles) from different classes, as well as in Micromonas. Our results show that, in accordance with recent observations from EST libraries and genome analyses, this polyol is produced by most ochrophytes, as well as the green alga tested, although it was found at a wide range of concentrations. Thus, the mannitol cycle was probably acquired by a common ancestor of most ochrophytes, possibly after the separation from diatoms, and may play different physiological roles in different classes.Key words: algae, stramenopiles, mannitol cycle, primary metabolism, osmotic stress, evolutionBrown algae produce mannitol directly from the photoassimilate fructose-6-phosphate. Its metabolism occurs through the mannitol cycle, which involves four enzymatic reactions: (1) the reduction of fructose-6-phosphate (F6P) to mannitol-1-phosphate (M1P) via the activity of an M1P dehydrogenase (M1PDH); (2) the production of mannitol from M1P via an M1P phosphatase (M1Pase); (3) the oxidation of mannitol via the activity of a mannitol-2-dehydrogenase (M2DH) yielding fructose; and (4) the phosphorylation of fructose yielding F6P and involving a hexokinase (HK).^1,2 The first completed draft of a brown algal genome enabled the identification of candidate genes for each of these steps.³ As these genes were not found in the genomes of the diatoms Thalassiosira pseudonana and Phaeodactylum tricornutum, mannitol metabolism in stramenopiles was considered a trait typical for brown algae. The corresponding genes were thought to have been acquired horizontally from bacteria and subsequently transferred to some green algae.⁴ Recently, however, homologs of several genes of the cycle were also found in the genome of the pelagophyte Aureococcus anophagefferens⁵ and an EST library produced for the dictyochophyte Pseudochattonella farcimen (Dittami et al. personal communication). These observations prompted us to examine the presence of mannitol in a range of strains covering different classes of autotrophic stramenopiles (ochrophytes). In addition, because of the identification of genes encoding enzymes for the production of mannitol through the mannitol cycle in the green alga Micromonas, one strain of this genus was also included in our analysis.     

高温油藏内源微生物及其提高采收率潜力研究

大港孔店油田油藏特征、流体和微生物性质分析结果表明, 属于高温生态环境, 地层水矿化度较低, 氮、磷浓度低, 而且缺乏电子受体, 主要的有机物来源是油气。油田采用经过除油处理的油藏产出水回注方式开发, 油层中存在的微生物类型主要是厌氧嗜热菌, 包括发酵菌(102个/mL~105个/mL), 产甲烷菌(103个/mL); 好氧菌主要存在于注水井周围。硫酸盐还原菌(SRB)还原速率0.002 mg S2-/(L·d) ~18.9 mg S2-/(L·d), 产甲烷菌产甲烷速率0.012 mgCH4/(L·d)~16.2 mgCH4/(L·d)。好氧菌能够氧化油形成生物质, 部分氧化产物为挥发性脂肪酸和表面活性剂。产甲烷菌在油氧化菌液体培养基中产生CH4, CO2为好氧微生物和厌氧微生物的共同代谢产物。这些产物具有提高原油流动性的作用。用示踪剂研究了注入水渗流方向。通过综合分析, 油藏微生物具有较大的潜力, 基于激活油层菌的提高采收率方法在该油田是可行的。     

Evolutionary trend in feeding habits of <Emphasis Type="Italic">Girella</Emphasis> (Perciformes: Girellidae)

Although some Girella species are herbivorous, having basically tricuspid teeth, some are omnivorous. To determine the evolutionary trends in feeding habits of Girella, the phylogenetic relationships of several species of Girella were estimated by partially sequencing the mitochondrially encoded NADH dehydrogenase subunit 2 gene, and the dentition and adductor mandibulae complex of each species were examined. The cladogram determined from the mitochondrial DNA analysis indicated that multiple tooth-rows containing incisor-like teeth existed in adults of the ancestral species of Girella, species with a single tooth-row of tricuspid teeth in the adult stage having diverged subsequently on several occasions. The tendinous connections between each section of the adductor mandibulae complex are believed to have been simple in the ancestral species, more complicated connections also having diverged later on several occasions. Multiple tooth-rows containing incisor-like teeth and the simple adductor mandibulae complex are deduced as adaptations to herbivory; on the other hand, a single tooth-row of tricuspid teeth and the complicated adductor mandibulae complex are deduced as adaptations to omnivory. Therefore, the ancestral species of Girella is suggested as having been adapted to herbivory, with species adapted to omnivory having diverged on several subsequent occasions.