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251.
Changes in lipid composition of the oleaginous fungus Cunninghamella echinulata were monitored during growth. Lipid fractions and individual lipid classes varied in amount, relative proportions, and fatty acid profile depending on the developmental stage. Neutral lipids (N), comprised mainly of triacylglycerol, were accumulated in the fungal mycelium during both the late exponential and the stationary growth phases with a concomitant decrease in the amount of polar lipids. While fatty acid composition of N fraction remained almost constant, individual N classes showed a noticeable alteration in γ-linolenic acid (GLA) concentration. The glycolipid plus sphingolipid (G+S) fraction consisted mainly of monoglycosylglycerol and diglycosylglycerol. The sugar composition of G+S fraction was analyzed and showed a partial replacement of galactose for glucose as growth proceeded. Phospholipid (P) major classes were phosphatidylcholine (PC) and phosphatidylethanolamine, followed by phosphatidylinositol, phosphatidylserine, and diphosphatidylglycerol. P fatty acid composition showed significant changes with time, resulting in a considerable drop in the unsaturation index of this fraction. While in mid exponential growth phase, all P classes contained more than 20% w/w GLA of total fatty acids, and their concentration decreased to 12–17% w/w, except for the PC class where GLA concentration remained at high levels (e.g., more than 20% w/w). The constant level of GLA in PC at all growth phases suggests that PC was the major source of GLA. Sterol analysis showed that their concentration increased during growth, whereas ergosterol was the major component.  相似文献   
252.
Summary The genes coding for apolipoproteins A1, C3, and A4 (APOA1, APOC3, APOA4) are closely linked and tandemly organized within a 15-kilobase (kb) DNA segment on the long arm of human chromosome 11. The nucleotide variability of a 61-kb DNA segment containing these genes and their flanking sequences was studied by restriction analysis of a sample of 18 unrelated Northern Europeans using seven different genomic DNA probes. Eleven restriction site polymorphisms located within this DNA segment were used for haplotype analysis of 129 Mediterranean and 67 American black chromosomes. Estimation of the extent of nonrandom association between these polymorphisms indicated considerable linkage disequilibrium within the APOA1-APOC3-APOA4 gene cluster. Several haplotypes arose by recombination, and the rate of recombination within this gene cluster was estimated to be at least 4 times greater than that expected based on uniform recombination. The polymorphism information content of each of these polymorphisms, taken individually, ranges between 0.053 and 0.375, while that of their haplotypes ranges between 0.858 and 0.862. Therefore, DNA polymorphism haplotypes in the APOA1-APOC3-APOA4 gene cluster constitute a highly informative genetic marker on the long arm of human chromosome 11.  相似文献   
253.
Nucleotide sequence of turkey prolactin.   总被引:1,自引:1,他引:0       下载免费PDF全文
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254.
The response of larval fish communities of the northeastern Aegean Sea (NEA) to interannual environmental changes is analyzed using data from four ichthyoplankton surveys covering the NEA continental shelf during June 1993, 1994, 1995, and 1996. Waters were significantly cooler, less saline and richer in zooplankton in 1993 and 1996 (‘cold’ years) than in 1994 and 1995 (‘warm’ years). A comparison of monthly SST series (1993–1997) between the NEA, the Marmara Sea, and the Western Black Sea revealed high correlations and similar trend components among these areas implying that oceanographic conditions over the NEA (and observed inter-annual differences) were most likely dominated by the properties and relative amount of Black Sea water inflow in the NEA. The relative composition of the larval fish community was significantly related to the ‘cold/warm’ regime and larval diversity was higher during the warm years. Larvae of the small-sized pelagic species, such as anchovy (Engraulis encrasicolus), and most mesopelagic fishes were relatively more abundant during the cold, zooplankton-rich years. Larvae of the middle-sized pelagics (Sardinella aurita, Scomber japonicus, Trachurus mediterraneaus, Auxis rochei) and certain benthopelagic species exhibited an opposite trend, i.e., they were more abundant during the warm years or absent during the cold years. Most of these species are known to be typical summer spawners (e.g., Serranus cabrilla, Lisa saliens, Trachinus draco, and Symphurus nigrescens). Co-variation in larval fish production might be indicative of similar responses among species to changing physical and/or trophic regimes.  相似文献   
255.
Scolopendra cingulata Latreille, 1829 is the commonest scolopendromorph species in the Mediterranean area. However, its morphological and geographic variation has not been examined so far, and therefore robust hypotheses about the factors that have shaped that variability are lacking. We examined, using multivariate methods for 19 morphometric and meristic characters, the morphological variation of that species using a comprehensive sample of 503 adult specimens from 130 restricted geographic localities. The localities were distributed in three major geographic areas (Balkans, Asia Minor-Middle East, and Italy) in order to discern biological entities and to estimate the morphological relationships between populations and geographic regions. Results showed significant differences between the three geographic groups. Characters such as the distance between the paramedian sulci of the 7th and 8th tergite, the number of antennal segments, the number of spines on the dorsal side of 21st prefemur and number of spines on the 21st prefemoral process significantly discriminated populations of S. cingulata along a west-east geographic gradient. Both eastern (Balkan) and easternmost populations (Asia Minor-Middle East) showed higher mean values of antennal articles and spines of 21st prefemur than the Italian populations. No significant morphological variation was discovered between the sexes of S. cingulata apart from cephalic width and distance between the two paramedian sulci of the 7th and 8th tergite. Based on certain morphometric differences among the three major geographic regions, we suggest that S. cingulata originated in the east and colonized south European area from two different geographic routes. It is suggested that west-east morphological trend of S. cingulata is related either to the prominent palaeogeographic events of the area or to the competition with S. oraniensis Lucas, 1846 in the western Mediterranean.  相似文献   
256.
Gross contraction in skeletal muscle is primarily determined by a relatively small number of contractile proteins, however this tissue is also remarkably adaptable to environmental factors1 such as hypertrophy by resistance exercise and atrophy by disuse. It thereby exhibits remodeling and adaptations to stressors (heat, ischemia, heavy metals, etc.)2,3. Damage can occur to muscle by a muscle exerting force while lengthening, the so-called eccentric contraction4. The contractile proteins can be damaged in such exertions and need to be repaired, degraded and/or resynthesized; these functions are not part of the contractile proteins, but of other much less abundant proteins in the cell. To determine what subset of proteins is involved in the amelioration of this type of damage, a global proteome must be established prior to exercise5 and then followed subsequent to the exercise to determine the differential protein expression and thereby highlight candidate proteins in the adaptations to damage and its repair. Furthermore, most studies of skeletal muscle have been conducted on the male of the species and hence may not be representative of female muscle. In this article we present a method for extracting proteins reproducibly from male and female muscles, and separating them by two-dimensional gel electrophoresis followed by high resolution digital imaging6. This provides a protocol for spots (and subsequently identified proteins) that show a statistically significant (p < 0.05) two-fold increase or decrease, appear or disappear from the control state. These are then excised, digested with trypsin and separated by high-pressure liquid chromatography coupled to a mass spectrometer (LC/MS) for protein identification (LC/MS/MS)5. This methodology (Figure 1) can be used on many tissues with little to no modification (liver, brain, heart etc.).  相似文献   
257.
Solid oxide fuel cells (SOFCs) have grown in recognition as a viable technology able to convert chemical energy directly into electricity, with higher efficiencies than conventional thermal engines. Direct feeding of the SOFCs anode with hydrocarbons from fossil or renewable sources, appears more attractive compared to the use of hydrogen as a fuel. The addition of mixed oxide‐ion/electron conductors, like gadolinium‐doped ceria (GDC), to commonly used nickel‐based anodes is a well–known strategy that significantly enhances the performance of the SOFCs. Here we provide in situ experimental evidence of the active surface oxidation state and composition of Ni/GDC anodes during methane electroxidation using realistic solid oxide electrode assemblies. Ambient pressure X‐ray photoelectron and near edge X‐ray absorption fine structure spectroscopies (APPES and NEXAFS respectively) combined with on line electrical and gas phase measurements, were used to directly associate the surface state and the electrocatalytic performance of Ni/GDC anodes working at intermediate temperatures (700°C). A reduced anode surface (Ce3+ and Ni), with an optimum Ni to Ce surface composition, were found to be the most favorable configuration for maximum cell currents. Experimental results are rationalized on the basis of first principles calculations, proposing a detailed mechanism of the cell function.  相似文献   
258.
Approximately 70% to 80% of patients with urothelial carcinomas of the bladder are initially diagnosed with non-muscle invasive disease. Superficial, non-muscle invasive bladder cancers (NMIBCs) are managed with cystoscopic transurethral resection of all visible lesions followed by intravesical chemotherapy and/or immunotherapy. Despite this treatment, up to 70% of these tumors will recur within five years and 15% will ultimately progress to muscle-invasive disease, suggesting that novel therapeutic strategies are necessary. Recent studies have greatly advanced our understanding of urothelial carcinogenesis and have highlighted the distinct molecular pathogenesis of NMIBCs versus muscle-invasive bladder tumors. It is now clear that diverse genetic and epigenetic events are driving the oncogenesis of NMIBCs, thereby attesting to their potential as therapeutic targets for these tumors. This article reviews the molecular pathogenesis of NMIBCs, discusses recently completed and ongoing clinical trials and anticipates the future direction of molecular targeted agents in this disease.  相似文献   
259.
Cadmium (Cd) is an environmental contaminant known to exert significant neurotoxic effects on both humans and experimental animals. The aim of this study was to shed more light on the effects of gestational (in utero) and lactational maternal exposure to Cd (50 ppm of Cd as Cd-chloride in the drinking water) on crucial brain enzyme activities in important rat offspring brain regions (frontal cortex, hippocampus, hypothalamus, pons and cerebellum). Our study provides a brain region-specific view of the changes in the activities of three crucial brain enzymes as a result of the developmental neurotoxicity of Cd. Maternal exposure to Cd during both gestation and lactation results into significant changes in the activities of acetylcholinesterase and Na+,K+-ATPase in the frontal cortex and the cerebellum of the offspring rats, as well as in a significant increase in the hippocampal Mg2+-ATPase activity. These brain-region-specific findings underline the need for further research in the field of Cd-induced developmental neurotoxicity. Deeper understanding of the mechanisms underlying the neurodevelopmental deficits taking place due to in utero and early age exposure to Cd could shed more light on the causes of its well-established cognitive implications.  相似文献   
260.
The oxidative modification of LDL may play an important role in the early events of atherogenesis. Thus the identification of antioxidative compounds may be of therapeutic and prophylactic importance regarding cardiovascular disease. Copper-chlorophyllin (Cu-CHL), a Cu2+-protoporphyrin IX complex, has been reported to inhibit lipid oxidation in biological membranes and liposomes. Hemin (Fe3+-protoporphyrin IX) has been shown to bind to LDL thereby inducing lipid peroxidation. As Cu-CHL has a similar structure as hemin, one may assume that Cu-CHL may compete with the hemin action on LDL. Therefore, in the present study Cu-CHL and the related compound magnesium-chlorophyllin (Mg-CHL) were examined in their ability to inhibit LDL oxidation initiated by hemin and other LDL oxidizing systems. LDL oxidation by hemin in presence of H2O2 was strongly inhibited by both CHLs. Both chlorophyllins were also capable of effectively inhibiting LDL oxidation initiated by transition metal ions (Cu2+), human umbilical vein endothelial cells (HUVEC) and tyrosyl radicals generated by myeloperoxidase (MPO) in presence of H2O2 and tyrosine. Cu- and Mg-CHL showed radical scavenging ability as demonstrated by the diphenylpicrylhydracylradical (DPPH)-radical assay and estimation of phenoxyl radical generated diphenyl (dityrosine) formation. As assessed by ultracentrifugation the chlorophyllins were found to bind to LDL (and HDL) in serum. The present study shows that copper chlorophyllin (Cu-CHL) and its magnesium analog could act as potent antagonists of atherogenic LDL modification induced by various oxidative stimuli. As inhibitory effects of the CHLs were found at concentrations as low as 1 μmol/l, which can be achieved in humans, the results may be physiologically/therapeutically relevant.  相似文献   
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