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51.
Summary The recessive embryo-lethal mutantdek-1 of maize, showing arrest of embryo development at the proembryo stage, lack of carotenoids and anthocyanins and absence in the endosperm of the aleurone layer, was characterized at a cytological level. Cytofluorimetric analysis excluded endoreduplication or polyploidization events in mutant embryonic cells, in spite of an evident increase in nucleolus and nucleus diameters.The data seem to point to an involvement ofDek-1 in the progression of the embryo toward specific developmental steps and in the differentiation of the aleurone layer in the endosperm. Cellular proliferation is not affected by the mutation, as is shown by DNA replication even after the arrest in development and by the possibility of inducing callus from mutant embryos.Abbreviation DAP
days after pollination 相似文献
52.
(20S)-[7,7,21,21-2H(4)]-3beta-(tert-Butyldimethylsilanyloxy)-20-methyl-pregn-5-en-21-ol, an intermediate for the preparation of deuterated isotopomers of sterols to be used as standards for biomedical studies, was prepared by reduction with dichloroaluminum deuteride of ethyl (20S)-3beta-(tert-butyldimethylsilanyloxy)-7-oxo-pregn-5-en-20-carboxylate. Using controlled experimental conditions, it has also been shown that the dichloroaluminum hydride reduction of a 7-keto steroid affords the corresponding 7beta-hydroxy derivative in a highly stereoselective manner. 相似文献
53.
Asolene platae (Ampullariidae) is a dioecious freshwater snail with subaquatic gelatinous egg masses that dwells in the Río de la Plata basin (Argentina). The aim of this study was to describe the inheritance mechanism of the colour variations of the shell and soft parts of this snail, and to study their potential use as a genetic marker. The wild-type phenotype presents dark pigments in the soft parts and in shell bands, whereas the yellow phenotype lacks dark pigments in the soft parts and also most dark bands in the shell, except for a subsutural and a periumbilical band. The data showed that the lack of pigments in A. platae is a recessive homozygotic condition with a simple Mendelian inheritance mechanism. Females of the wild-type phenotype had a higher number of bands than the males. The pigment of the bands of both phenotypes is located in the calcareous matrix of the shell. Using the lack of pigments as a genetic marker we demonstrated the existence of biparental egg masses in A. platae, hitherto known in only one species within the Ampullariidae. 相似文献
54.
Vaisburg A Bernstein N Frechette S Allan M Abou-Khalil E Leit S Moradei O Bouchain G Wang J Woo SH Fournel M Yan PT Trachy-Bourget MC Kalita A Beaulieu C Li Z MacLeod AR Besterman JM Delorme D 《Bioorganic & medicinal chemistry letters》2004,14(1):283-287
A variety of omega-substituted alkanoic acid (2-amino-phenyl)-amides were designed and synthesized. These compounds were shown to inhibit recombinant human histone deacetylases (HDACs) with IC(50) values in the low micromolar range and induce hyperacetylation of histones in whole cells. They induced expression of p21WAF1/Cip1 and caused cell-cycle arrest in human cancer cells. Compounds in this class showed efficacy in human tumor xenograft models. 相似文献
55.
56.
Effect of different growth hormone dosages on the growth velocity in children born small for gestational age 总被引:3,自引:0,他引:3
To assess whether short-term growth hormone (GH) treatment can improve the linear growth in children who were born small for gestational age (SGA), we started a randomized multicenter trial in 26 age- and sex-matched prepubertal children born SGA. During the 1st year of GH therapy, all children received GH 0.23 mg/kg/week, then during the 2nd year, 13 children received the same dose (group A), and in the other 13 children, the dose of GH was doubled, i.e., 0.46 mg/kg/week (group B). During the 1st year of therapy, the growth velocity significantly (p<0.0001) increased in all patients. During the 2nd year, group A showed a significant decrease of the growth velocity (p<0.015), whereas group B maintained the growth rate. The height in group A children significantly increased during the 1st and the 2nd year of GH therapy (p<0.000002 and p<0.000001, respectively), reaching the normal range in 8 out of 13 children at the end of 2 years of GH therapy. The height in group B children significantly increased during the 1st and the 2nd year of GH therapy (p<0.000001 and p<0.000001, respectively), reaching the normal range in all 11 children who completed the GH therapy. The height gain was similar in groups A and B treated with the same GH dosage during the 1st year of therapy. A greater increase in height gain was found in children of group B treated with the higher GH dosage during the 2nd year of therapy as compared with group A (p<0.02). Significant increases in insulin-like growth factor I (p<0.0001), acid-labile subunit (p<0.0002), and bone/chronological age ratio (p<0.0001) were found after the 1st year of GH therapy, but no significant changes were observed during the 2nd year, independently of the GH dose. In conclusion, the height velocity of children born SGA significantly increases during the 1st year of GH therapy, diminishes, but can decrease during the 2nd year, if the GH dosage is not raised. 相似文献
57.
The armored catfish Hypostomus affinis is a widespread Loricariidae fish in the Lajes Reservoir (22 degrees 42'-22 degrees 50' S; 43 degrees 53'-44 degrees 05' W), the largest lentic environment in the Rio de Janeiro State, but little is known about their reproductive biology. One hundred and twenty five females, captured from January 1996 to December 1997, were used to assess ovarian development (29 were used to determine fecundity). The oocyte distribution by size-diameter classes revealed the occurrence of two modes suggesting an asynchronic development of the ovaries. The total fecundity ranged from 1235 to 4304, averaging 2374. An exponential relationship between fecundity and total length was determined, and a direct linear relationship was found between fecundity and total weight and gonad weight. 相似文献
58.
Riggio M Filosa S Parisi E Scudiero R 《Comparative biochemistry and physiology. Toxicology & pharmacology : CBP》2003,135(2):191-196
In the present report, we investigated zinc, copper and metallothionein (MT) contents in zebrafish oocytes and embryos. Our results demonstrate that the metal content increases during oocytes maturation. Zinc increases from 30 ng/oocyte (stage-1 oocytes) to 100 ng/oocyte (stage-3 oocytes); copper varied from 1 ng/oocyte (stage-1 oocytes) to 3.5 ng/oocyte (stage-3 oocytes). During embryogenesis, zinc and copper contents dramatically increase after fertilisation around the 512-cells stage, then slowly decrease until the mid-gastrula stage. During oocyte growth, the changes in the MT level are proportional to metal content, whereas during embryogenesis the pattern of MT accumulation does not parallel that of the two metals. Indeed, the maternal pool of MT decreases steadily during the early stages of the development until the gastrula stage. We have examined the effect of cadmium on the expression of MT during zebrafish development. After cadmium exposure, MT content increases in embryos at the blastula stage, whereas no induction occurs in embryos at the gastrula stage. However, pre-treatment of embryos at the gastrula stage with 5-aza-2'-deoxycytidine induces MT synthesis following exposure to cadmium. These observations show that changes in metal levels are not correlated to MT content in the embryo, whereas DNA methylation is one of the factors regulating MT expression. 相似文献
59.
The susceptibility or resistance to 26 antimicrobial agents was determined for 64 strains of Listeria monocytogenes and 102 strains of L. innocua isolated from Italian meat products. Some strains of L. monocytogenes were found to be resistant to tetracycline, erythromycin, co-trimoxazole and clindamycin. No plasmids were found in any L. monocytogenes strain. Five strains of L. innocua contained a 7.9 kbp plasmid, but these isolates were not resistant to any antibiotic in common and treatment with curing agents could not eliminate resistance to antibiotics. These results suggest that antibiotic resistance was not likely to be plasmid mediated in our strains. 相似文献
60.
Barbara Bottazzi Laura Santini Silvana Savino Marzia M. Giuliani Ana I. Due?as Díez Giuseppe Mancuso Concetta Beninati Marina Sironi Sonia Valentino Livija Deban Cecilia Garlanda Giuseppe Teti Mariagrazia Pizza Rino Rappuoli Alberto Mantovani 《PloS one》2015,10(3)
Long pentraxin 3 (PTX3) is a non-redundant component of the humoral arm of innate immunity. The present study was designed to investigate the interaction of PTX3 with Neisseria meningitidis. PTX3 bound acapsular meningococcus, Neisseria-derived outer membrane vesicles (OMV) and 3 selected meningococcal antigens (GNA0667, GNA1030 and GNA2091). PTX3-recognized microbial moieties are conserved structures which fulfil essential microbial functions. Ptx3-deficient mice had a lower antibody response in vaccination protocols with OMV and co-administration of PTX3 increased the antibody response, particularly in Ptx3-deficient mice. Administration of PTX3 reduced the bacterial load in infant rats challenged with Neisseria meningitidis. These results suggest that PTX3 recognizes a set of conserved structures from Neisseria meningitidis and acts as an amplifier/endogenous adjuvant of responses to this bacterium. 相似文献