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71.
The reference ranges of the trace elements Al, As, Be, B, Cd, Co, Cu, Fe, Mn, Mo, Ni, Pb, Li, Rb, Se, Sr, and Zn were determined by inductively coupled plasma-mass spectrometry (ICP-MS) in sera of a group of free-ranging plains viscachas of the pampa grasslands of Argentina. The values were compared with those of a small group of captive plains viscachas of the Zurich Zoo with diabetes and bilateral cataracts. In addition, a method for digestion of whole-blood samples is described for the trace element determination. Significant differences in the concentration of trace elements in the two groups of animals are discussed. No correlation was found between the levels of selenium and of other trace elements compared to the formation of cataracts.  相似文献   
72.
曲酸生产菌的复合诱变选育*   总被引:9,自引:0,他引:9  
以黄曲霉(Aspergillus flavus.)为出发菌株,经3次紫外线、1次^60Co、3次亚硝基胍多重复合诱变处理,选育获得曲酸生产菌UCN7—17,配以最佳培养条件,发酵7d,曲酸产量由原来的0.926%,提高到6.3%。实验证明采用多因子复合诱变,能有效改变菌株对诱变因素敏感性,提高变异率,逐步提高突变株的产酸水平。  相似文献   
73.
A new series of coumarin-yl-chalcone derivatives (3a-m) had been designed and synthesized through different reactions such as aromatic addition, cyclization and Claisen-Schmidt reactions in good yields (54–78%). 5-acetyl-4-(2-hydroxyphenyl) -6-methyl-3, 4-dihydropyrimidin-2(1H) -one (1) has been synthesized by multi-component one pot reaction of salicylaldehyde, methyl acetoacetate and urea, which was further reacted with malonic acid employing ZnCl2 catalyst to yield 5-acetyl-4-(4-hydroxy-2-oxo-2H-chromen-8-yl) -6-methyl-3, 4-dihydropyrimidin-2(1H) -one (2). The title compounds (3a-m) were synthesised by reacting 5-acetyl-4-(4-hydroxy-2-oxo-2H-chromen-8-yl) -6-methyl-3, 4-dihydropyrimidin-2(1H)-one (2) with different aromatic aldehydes in the presence of potassium hydroxide. In silico studies, a preliminary screening method for predicting the anti-cancer activity was performed for the synthesized compounds (3a-m) against Src, Alb tyrosine kinase and homology model protein (PDB ID: 4csv). The derivatives 3h and 3m showed moderate binding energies. The in vitro cytotoxic activity was evaluated for the compounds 3h and 3m by using human cancer cell-line morphology and MTT assay against three human cell-lines A549 (Lung), Jurkat (Leukemia) and MCF-7 (Breast). The results indicate that the derivatives 3h and 3m display significant anti-cancer activity, however it was found to be less cytotoxic when compared to the standard used i.e. Imatinib.  相似文献   
74.
75.
With almost 900 described species, Hydraena Kugelann (Hydraenidae) is one of the largest genera among Coleoptera. The subgeneric classification of Hydraena has been controversial, with 11 subgeneric names having so far been attributed to it. Some of these, Haenydra Rey and Spanglerina Perkins, have been treated as valid genera, as subgenera or as species groups. The most recent complete treatment of the genus, based on a cladistic analysis of morphological characters, recognized two major lineages, and only these were classified as subgenera: Hydraenopsis (mainly Gondwanan distribution), and Hydraena s.str. (mainly Laurasian). Here, we reconstruct the phylogeny of Hydraena using 212 species plus several outgroups and approximately 4 kb of sequence data from two nuclear (SSU and LSU) and four mitochondrial genes (cox1, rrnL, trnL and nad1). Data were aligned with two different strategies of multiple alignment (implemented in mafft and prank ), and the phylogenies reconstructed using maximum likelihood and Bayesian methods. We estimated approximate ages of the main nodes using a relaxed molecular clock with Bayesian methods, and an a priori evolutionary rate of 0.01 substitutions/site/million years (Ma) plus a calibration point based on a biogeographical split. We found strong support for the monophyly of Hydraena and many of the clades recognized with morphological data. The following clades are considered as subgenera: Phothydraena Kuwert, Spanglerina Perkins, Holcohydraena Kuwert, Hydraenopsis Janssens and Hydraena s.str. The placement of three species groups, two Neotropical (H. multispina group, H. paeminosa group) and one South African/Madagascan (H. monikae group), is uncertain, and they are considered incertae sedis within Hydraena. The origin of the genus was estimated to be in the Lower Eocene, with many species complexes diversifying in the Pleistocene. Dispersal events seem to have played a key role in order to determine the current distribution of the species groups in the southern hemisphere (mainly in Hydraenopsis).  相似文献   
76.
CO2 responsiveness of plants: a possible link to phloem loading   总被引:5,自引:3,他引:2  
Of the many responses of plants to elevated CO2, accumulation of total non-structural carbohydrates (TNC in % dry weight) in leaves is one of the most consistent. Insufficient sink activity or transport capacity may explain this obvious disparity between CO2 assimilation and carbohydrate dissipation and structural investment. If transport capacity contributes to the problem, phloem loading may be the crucial step. It has been hypothesized that symplastic phloem loading is less efficient than apoplastic phloem loading, and hence plant species using the symplastic pathway and growing under high light and good water supply should accumulate more TNC at any given CO2 level, but particularly under elevated CO2. We tested this hypothesis by carrying out CO2 enrichment experiments with 28 plant species known to belong to groups of contrasting phloem-loading type. Under current ambient CO2 symplastic loaders were found to accumulate 36% TNC compared with only 19% in apoplastic loaders (P=0.0016). CO2 enrichment to 600 μmol mol?1 increased TNC in both groups by the same absolute amount, bringing the mean TNC level to 41% in symplastic loaders (compared to 25% in apoplastic loaders), which may be close to TNC saturation (coupled with chlornplast malfunction). Eight tree species, ranked as symplastic loaders by their minor vein companion cell configuration, showed TNC responses more similar to those of apoplastic herbaceous loaders. Similar results are obtained when TNC is expressed on a unit leaf area basis, since mean specific leaf areas of groups were not significantly different. We conclude that phloem loading has a surprisingly strong effect on leaf tissue composition, and thus may translate into alterations of food webs and ecosystem functioning, particularly under high CO2.  相似文献   
77.

Background  

Intoxication from the psychostimulant methamphetamine (METH) because of cardiovascular collapse is a common cause of death within the abuse population. For obvious reasons, the heart has been taken as the primary target for this METH-induced toxicity. The demonstration that failure of brain stem cardiovascular regulation, rather than the heart, holds the key to cardiovascular collapse induced by the pesticide mevinphos implicates another potential underlying mechanism. The present study evaluated the hypothesis that METH effects acute cardiovascular depression by dampening the functional integrity of baroreflex via an action on brain stem nuclei that are associated with this homeostatic mechanism.  相似文献   
78.
Hand‐rearing and assisted‐rearing aardvarks in captivity has become commonplace and has led to success in breeding the species. However, the macronutrient content of aardvark milk past 1 month of age is unknown. A better understanding of aardvark milk composition would enhance captive management efforts. Here, we assayed milk samples from two captive individuals from 2 to 114 days postpartum (N = 21) for dry matter, fat, crude protein, total sugar, ash (total minerals), calcium (Ca), phosphorus (P), and gross energy. The body weight of one calf was measured from birth to weaning. Milk macronutrient composition was compared to that of other Afrotherian species and Xenarthra species with similar diets. Average protein, fat, and sugar concentrations of aardvark milk across lactation were 12.3%, 13.6%, and 2.5%, respectively. Ash averaged 1.9%, with Ca (0.50%) and P (0.35%) accounting for about 45% of total minerals. All measured nutrients increased over lactation except sugar, which decreased. Aardvark milk is high in energy (2.12 kcal/g) mostly derived from fat and protein and little energy from sugar. Calf growth was linear (r2 = 0.995) with a mean gain of 159 g/day, achieving almost 30% of adult weight at weaning. Within Afrotheria, aardvark milk is higher in fat and protein and lower in sugar than elephant milk and more closely resembles the milk of its fellow insectivore, the elephant shrew. Aardvark milk is also similar in composition to milk of insectivorous Xenarthra species (nine‐banded armadillo and giant anteater). Aardvark milk composition is consistent with the species’ high‐protein diet, fast growth, and nursing pattern.  相似文献   
79.
Summary A cytochemical study on the endothelium of the hypodermic lymphatic capillaries of the green lizard,Lacerta hispanica, has been carried out. The dialysed iron method produced a homogeneous precipitate on the surface of the endothelial cells and on the inside of the endocytic vesicles. The periodic acid-thiocarbohydrazide-silver proteinate, low pH phosphotungstic acid and high iron diamine techniques gave negative results. The carbohydrates in the capillaries thus seem to be glycosaminoglycans with carboxyl groups. The possible role of these glycosaminoglycans in the formation of the endocytic vesicles is discussed.  相似文献   
80.

Background

TDP-43 proteinopathies are characterized by loss of nuclear TDP-43 expression and formation of C-terminal TDP-43 fragmentation and accumulation in the cytoplasm. Recent studies have shown that TDP-43 can accumulate in RNA stress granules (SGs) in response to cell stresses and this could be associated with subsequent formation of TDP-43 ubiquinated protein aggregates. However, the initial mechanisms controlling endogenous TDP-43 accumulation in SGs during chronic disease are not understood. In this study we investigated the mechanism of TDP-43 processing and accumulation in SGs in SH-SY5Y neuronal-like cells exposed to chronic oxidative stress. Cell cultures were treated overnight with the mitochondrial inhibitor paraquat and examined for TDP-43 and SG processing.

Results

We found that mild stress induced by paraquat led to formation of TDP-43 and HuR-positive SGs, a proportion of which were ubiquitinated. The co-localization of TDP-43 with SGs could be fully prevented by inhibition of c-Jun N-terminal kinase (JNK). JNK inhibition did not prevent formation of HuR-positive SGs and did not prevent diffuse TDP-43 accumulation in the cytosol. In contrast, ERK or p38 inhibition prevented formation of both TDP-43 and HuR-positive SGs. JNK inhibition also inhibited TDP-43 SG localization in cells acutely treated with sodium arsenite and reduced the number of aggregates per cell in cultures transfected with C-terminal TDP-43 162-414 and 219-414 constructs.

Conclusions

Our studies are the first to demonstrate a critical role for kinase control of TDP-43 accumulation in SGs and may have important implications for development of treatments for FTD and ALS, targeting cell signal pathway control of TDP-43 aggregation.  相似文献   
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