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101.
Summary Phenotypic analyses of genetic combinations involving the gene extramacrochaetae (emc) reveal its participation in the differentiation of both sensory elements and wing veins. The study of near-amorphic alleles of emc in mitotitc recombination clones indicates that it also affects cell proliferation. These clones show abnormal sizes, shapes and spatial distribution. They differentiate extra sensory elements as well as extra veins. A gain of function mutation in the gene causes opposite phenotypes in both differentiation systems. The effects of the mutant on proliferation and patterning are consistent with the emc gene being involved in the transfer of information between neighbouring cells, which leads to the spatial expression of the achaetescute gene complex and genes involved in vein formation. 相似文献
102.
J Skarda J Slaba P Krejcí I Mikulás 《Physiological research / Academia Scientiarum Bohemoslovaca》1992,41(2):151-155
The effects of administration of recombinantly derived bovine somatotropin (somidobove) in a sustained-release vehicle on the profiles of concentrations of bovine somatotropin (bST) in the blood plasma and on the milk yield of dairy cows of three herds were examined. Cows (36-87 days post partum) were treated subcutaneously with recombinant bST at 28-day intervals. In control animals, basal concentrations of bST averaged 1.4 ng.ml-1 in first-calf heifers and 1.5 ng.ml-1 in multiparous cows. In somidobove treated first-calf heifers, the concentration of bST was increased to 10.7, 14.5, and 27.0 ng.ml-1 at 24 h postinjection and in multiparous cows to 6.6, 11.0, and 11.7 ng.ml-1 on day 2 postinjection of 320, 640, and 960 mg of somidobove, respectively. On day 8 postinjection the average plasma bST levels of both parity groups are similar (on the average 3.4, 8.6, and 12.5 ng.ml-1 for three doses of somidobove respectively) and for the two highest doses being still significantly increased. During the 2nd week postinjection plasma bST concentration declined returning to control levels on day 15 postinjection. Somidobove-treated first-calf heifers produced 10.9, 16.7 and 17.9% and multiparous animals 25.5, 24.2 and 32.5% more milk than the controls when given 320, 640 and 960 mg somidobove, respectively. The cyclic pattern in milk yield within each 28-day injection interval was observed consistently in all herds. The milk yield increased to a maximum between day 4 to 8 postinjection and then slowly declined. Milk composition was not affected by somidobove treatment. 相似文献
103.
Control of Nitrogenase mRNA Levels by Products of Nitrate Assimilation in the Cyanobacterium Anabaena sp. Strain PCC 7120 总被引:1,自引:0,他引:1 下载免费PDF全文
Nitrate inhibited nitrogenase synthesis and heterocyst development in the cyanobacterium Anabaena sp. strain PCC 7120. Inhibition of dinitrogen fixation by nitrate did not take place, however, in nitrate reductase-deficient derivatives of this strain. Hybridization of total RNA isolated from cells grown on different nitrogen sources with an internal fragment of the nifD gene showed that regulation of nitrogenase activity by nitrate is exerted through a negative control of the nitrogenase mRNA levels. 相似文献
104.
Cecilia Zazueta José A. Holguín Jorge Ramírez 《Journal of bioenergetics and biomembranes》1991,23(6):889-902
We describe a calcium transport that is sensitive to ruthenium red in liposomes reconstituted with mitochondrial extracts. This system is able to build an internally negative membrane potential, which allows the electrogenic influx of Ca2+ and Sr2+. Proteins with molecular weights higher than 35 kDa were incorporated to the vesicles, and enhanced the accumulation of the cation in an energy-dependent fashion. 相似文献
105.
Helicobacter pylori in Barrett's esophagus. 总被引:2,自引:0,他引:2
J C Ferreres F Fernández A Rodríguez Vives I González-Rodilla I Ursúa R Ramos J F Val-Bernal 《Histology and histopathology》1991,6(3):403-408
Barrett's esophagus is an anatomicoclinical state in which, due to the prolonged action of gastroesophageal reflux, the squamous epithelium is replaced by columnar epithelium. Helicobacter pylori has been implicated in the pathogenesis of various gastrointestinal disorders and has occasionally been observed in Barrett's esophagus. The aim of this study is to determine the incidence of H. pylori in Barrett's esophagus and try to establish its role in the pathogenesis of this disorder. H. pylori was observed in 31 biopsies (44.3%) of the 70 studied, mainly when the epithelium is of the gastric atrophic-fundic type (p less than 0.01). Its presence shows no relation to the degree of inflammatory activity and does not seem, therefore, to play an important role in the pathogenesis of the lesion. 相似文献
106.
Immunocytochemical and ultrastructural characterization of endocrine cells in chicken proventriculus
Summary The endocrine cells of the chicken proventriculus were investigated immunocytochemically, using the peroxidase-antiperoxidase technique on paraffin and semithin sections for light microscopy, and immunogold staining in osmium-fixed material for electron microscopy. The fixation procedure also allowed a detailed ultrastructural investigation. Twenty-three antisera were tested and 7 immunoreactive cell-types were identified: D-cells containing somatostatin-like peptide; EG-cells immunoreactive to anti-glucagon, anti-GLP1 and antineurotensin; NT-cells labelled only with anti-neurotensin; BN-cells containing bombesin-like material; ENK-cells showing met-enkephalin immunoreactivity; EC-cells reactive to anti-serotonin; and APP-cells positive to anti-avian pancreatic polypeptide. In addition, enterochromaffin-like (ECL) cells, were also detected by electron microscopy. The presence of ENK-cells and the ultrastructure of these and NT-cells are described for the first time in chicken proventriculus, and glucagon, GLP1 and neurotensin are shown to be colocalized in the EG-cells. 相似文献
107.
108.
The effect of twelve detergents on aspartate ammonia-lyase activity of Escherichia alcalescens used for the production of L-aspartic acid was tested. Best permeabilization was found with Triton X-100, Slovafol 910 and Corona, a mixed commercial preparation. In contrast to Triton X-100 and Slovafol 910, a much narrower range of suitable concentrations was observed with Corona. 相似文献
109.
R Wainstok de Calmanovici L C San Martín de Viale 《The International journal of biochemistry》1988,20(9):1015-1020
1. The porphyrinogenic ability of several antineoplastics used in the therapy of the different cancers was evaluated. The action of cyclophosphamide, busulfan and 5-fluorouracil on the amount and nature of the accumulated hepatic porphyrins and on the activity of delta-aminolaevulinate synthase (ALA-S), were estimated at different doses and times of drug treatment in 17-day-old chick embryos. 2. It was observed that cyclophosphamide produces a significant increase in the accumulation of hepatic porphyrins at different doses as well as in the activity of the ALA-S, at all the incubation times. Cyclophosphamide alters the pattern of porphyrins accumulated in the liver, where a coproporphyrin: protoporphyrin ratio higher than in the controls can be observed. 3. Busulfan increased the hepatic porphyrins accumulated in the liver but to a lesser degree than cyclophosphamide. 4. 5-Fluorouracil did not modify the hepatic porphyrin content when it was administered at doses up to 40 mg/embryo. 5. When the embryos were injected with busulfan or 5-fluorouracil no significant differences were observed in the activity of ALA-S up to 11 hr of incubation. 6. These results indicate that cyclophosphamide has a remarkable porphyrinogenic capacity in chick embryo while busulfan, notwithstanding the fact that it alters the haem pathway, it does so to a degree that does not impair the regulation of ALA-S activity. Fluorouracil seems to be non porphyrinogenic in this system, up to 40 mg/embryo. 相似文献
110.
Presence of aflatoxin M1 in commercial ultra-high-temperature-treated milk. 总被引:1,自引:0,他引:1 下载免费PDF全文
J L Blanco L Domínguez E Gmez-Lucía J F Garayzabal J A García G Surez 《Applied microbiology》1988,54(6):1622-1623
Forty-seven samples of commercial ultra-high-temperature-treated milk from a dairy facility in the northwest part of Spain were analyzed for the presence of aflatoxin M1. A total of 14 samples (29.8%) were positive for aflatoxin M1 (4 in May, 3 in November, 3 in December, 1 in January, 1 in April, 1 in July, and 1 in August), 29 (61.7%) were negative, and 4 (8.5%) were doubtful, i.e., they showed trace quantities of aflatoxin M1. The range of aflatoxin M1 content was 0.02 to 0.1 ng/ml. 相似文献