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Abstract: The enzymatic hydrolysis of UDP-galactose in rat and calf brain was studied. The hydrolysis occurs in two steps: The first is the conversion of UDP-galactose to galactose-1-phosphate catalyzed by nucleotide pyrophosphatase (EC 3.6.1.9), and the second is the conversion of the latter to free galactose by alkaline phosphatase (EC 3.1.3.1). The overall conversion has a pH optimum of 9.0, but there is considerable activity at pH 7.4, which is the optimum for UDP-galactose:ceramide galactosyltransferase in the synthesis of cerebrosides. Preparations from cytosol from calf brain cerebellum or stem that were enriched in UDP-galactose hydrolytic activity inhibit cerebroside synthesis under conditions optimal for the synthesis. Microsome-rich and nuclear debris fractions contain the highest apparent specific activity among the subcellular fractions studied. Hydrolysis of UDP-galactose occurs in all areas of brain, brainstem having the highest activity. The apparent specific activity in jimpy mouse brain homogenate is nearly twice as high as in the control brain homogenate.  相似文献   
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Pseudorabies, a herpesvirus infection, is mainly controlled by using attenuated live vaccines. In this study, the effect of ginseng stem and leaf saponins (GSLS) in combination with selenium (Se; in the form of sodium selenite) on vaccination against attenuated pseudorabies virus (aPrV) was evaluated. It was found that GSLS and Se have an adjuvant effect and that a combination of GSLS and Se stimulates significantly enhanced immune responses than does GSLS or Se alone. Following oral administration of GSLS, mice immunized with an attenuated PrV vaccine diluted in Se‐containing physiological saline solution (PSS) provoked a significantly stronger gB‐specific serum antibodies response (IgG, IgG1 and IgG2a), enhanced lymphocyte proliferation and cytolytic activity of NK cells, along with higher production of cytokines (IFN‐γ, IL‐12, IL‐5 and IL‐10) by splenocytes. Notably, the combination of GSLS and Se conferred a much higher resistance to fPrV challenge after immunization of the mice with aPrV vaccine. This study offers convincing experimental evidence that an injection of Se with oral GSLS is a promising adjuvant combination that improves the efficacy of vaccination against PrV and deserves further study regarding improvement of responses to other animal vaccines.  相似文献   
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The Indochinese silvered langur (Trachypithecus germaini) is distributed to the west of Mekong River in Cambodia, Lao PDR, Thailand and Vietnam. During a two‐year study, from May 2014 to May 2016, we collected 320.44 hr of behavior, with 17,040 feeding bouts recorded (142 hr) for T. germaini on Chua Hang Karst Mountain, Kien Luong District, Kien Giang Province, Vietnam. Feeding accounted for 45% of the Indochinese silvered langurs’ activity budget. The plant diet of the Indochinese silvered langurs was principally composed of young leaves (58%), followed by mature leaves (9.5%), fruits (22.7%), flowers (4.7%), buds (3.3%), petioles (1.2%), and other (0.5%). A total of 58 plant species were fed on by the silvered langurs, and leaves of eight species (Phyllathus reticulatus, Ficus rumphii, Ficus tinctoria, Ficus microcarpa, Cayratia trifolia, Streblus ilicifolia, Combretum latifolium, and Streblus asper) were fed on throughout the year. P. reticulatus was most frequently eaten (13.9% feeding time, n = 1,733). Food selection differed significantly between months and seasons. The Indochinese silvered langurs ate 27 plant species in the wet season compared with 23 plant species in the dry season. Leaf chemical composition of two food categories, 16 eaten species (with 10 most frequently consumed species and six least consumed species), and four noneaten species, were analyzed. Feeding samples from eaten species in the Indochinese silvered langurs's diet contained lower amounts of condensed tannin, lignin, protein, ash, and lipids, but a higher amount of total sugar compared with samples from noneaten species. Furthermore, the most frequently consumed species contained lower amounts of lignin compared with the less frequently consumed species. Using a generalized linear model with five variables, including neutral detergent fiber (NDF), total sugar, lignin, lipid, and calcium (Ca) indicated that NDF positively correlated and lignin content negatively correlated with feeding records in the diet of these langur.  相似文献   
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The developmental morphology and growth dynamics of the tobacco leaf   总被引:5,自引:0,他引:5  
R. S. Poethig  I. M. Sussex 《Planta》1985,165(2):158-169
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Cell cultures of the carrot Daucus carota are a useful experimental system for studying the genetic regulation of plant embryogenesis. A modified filtration-enrichment procedure was used to isolate 21 temperature-sensitive variants in somatic embryogenesis; the variants display normal embryo development at the permissive temperature (24°C) and altered development at the restrictive temperature (33°C). Temperature-shift experiments were performed on these variants to determine the timing of gene action for the putative temperature-sensitive alleles. According to their phenotypes at the restrictive temperature, these variants can be divided into six classes: No Growth, Callus Proliferation, Globularstage Block, Oblong-stage Block, Lateral Growth, and Root Formation. Although many variants exhibit lengthy temperature-sensitive periods, the temperature sensitivity of some variants is restricted to one or two embryonic stages. These results plus those in the literature are incorporated into a preliminary model concerning the genetic regulation of carrot embryogenesis.  相似文献   
29.
A pCTVHyg plasmid was constructed in a unicellular green alga Chlamydomonas reinhardtii Dang. by using the hygromycin phosphotransferase gene (hpt) as a selectable marker and the Escherichia coli transposon Tn5 under the early SV40 viral gene promoter. CW-15 mutant cells devoid of cell walls were transformed by electroporation in an electric field of 1 kV/cm and a pulse duration of 2 ms. A suspension density of 106 cell/ml and the mid-logarithmic growth phase were the optimum conditions for transformation, producing up to 103 hygromycin-resistant (HygR) clones per 106 HygR recipient cells. Exogenous DNA integrated in the nuclear genome of C. reinhardtii was steadily inherited in subsequent generations within at least a 8-month period; however, the HygR trait manifestation was not stable. The comparative analysis of frequencies in codon usage in hpt and in the nuclear genes of C. reinhardtii significantly excluded the possibility that the bias in codon usage was the primary factor affecting foreign gene expression. The advantages of using theCW-15 mutant and the described selection system are discussed in the context of heterologous transformation of C. reinhardtii.  相似文献   
30.
We recently reported an abnormal production of interleukin-1 (IL-1) in peripheral macrophages of several neurological mutant mice that exhibit patterns of neuronal degeneration, especially in the cerebellum. After in vitro activation by lipopolysaccharide acid (LPS), these macrophages hyperexpress IL-1 beta mRNA and hyperproduce IL-1 protein in comparison with +/+ controls. In the present study, focused on the staggerer mutant mice, we investigate if this genetic dysregulation is specific for IL-1 beta or if it reflects a generalized hyperexcitability of these macrophages. The hyperexpression of IL-1 beta mRNA in sg/sg macrophages is present whatever the duration of LPS stimulation, even for periods as short as 15 min, although it reaches a maximum after 4 h of stimulation. The hyperinducibility of sg/sg macrophages is observed even when very low doses of LPS are used (0.01 microgram/ml) and reaches its maximum for 5 micrograms/ml LPS. Synthetic molecules (muramyl dipeptides), such as N-acetylmuramyl-L-alanyl-D-isoglutamine or murabutide, known as macrophage activators, are also efficient in revealing the cytokine hyperexpression in sg/sg macrophages. In addition, hyperexpression of two other cytokines, i.e., tumor necrosis factor-alpha and IL-1 alpha mRNAs, is also detected in LPS-stimulated macrophages of mutant mice. Finally, the effect of an inhibitor of protein synthesis, cycloheximide, is similar in +/+ and sg/sg macrophages. As a whole, these data lead us to conclude that the sg/sg macrophages are in a state of general hyperexcitability when compared with +/+ ones.  相似文献   
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