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981.
A karyological analysis was carried out on two populations ofTriturus montandoni, one from Poland and another from Rumania. For both samples, morphometric characteristics and C-banding pattern of mitotic
chromosomes are provided. Only slight differences between specimens from two geographic localities were found.
Data on chiasma frequency and distribution are presented for male meiosis. No sex-related heteromorphism was found and for
none of the chromosomal arms was a consistent absence of chiasmata recorded. There was a relatively high proportion of spermatocyte
metaphases I with chiasmata on both arms of all chromosomes in all specimens studied. It is concluded that there are no well-defined
sex chromosomes in the chromosomal complement of the maleT. montandoni.
The findings are compared with previous studies on chromosome morphology, C-banding pattern, and meiosis in closely related
species,T. vulgaris andT. helveticus. 相似文献
982.
Tomasz Molcan Sylwia Swigonska Anna Nynca Agnieszka Sadowska Monika Ruszkowska Karina Orlowska Renata E. Ciereszko 《Biochimica et Biophysica Acta (BBA)/General Subjects》2019,1863(2):291-303
2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) is the most difficult to biodegradate and the most toxic dioxin congener. Previously, we demonstrated in silico the ability of pig CYP1A1 to hydroxylate 2,7-dichlorodibenzo-p-dioxin (DiCDD), but not TCDD. To increase our knowledge concerning the low effectiveness of TCDD biodegradability, we analyzed in silico the binding selectivity and affinity between pig CYP1B1 and the two dioxins by means of molecular modeling. We also compared the effects of TCDD and DiCDD on CYP1B1 gene expression (qRT-PCR) and catalytic (EROD) activity in porcine granulosa cells. It was found that DiCDD and TCDD were stabilized within the pig CYP1B1 active site by hydrophobic interactions. The analysis of substrate channel availability revealed that both dioxins opened the exit channel S, allowing metabolites to leave the enzyme active site. Moreover, DiCDD and TCDD increased the CYP1B1 gene expression and catalytic activity in porcine granulosa cells. On the other hand, TCDD demonstrated higher than DiCDD calculated affinity to pig CYP1B1, hindering TCDD exit from the active site. The great distance between CYP1B1's heme and TCDD also might contribute to the lower hydroxylation effectiveness of TCDD compared to that of DiCDD. Moreover, the narrow active site of pig CYP1B1 may immobilize TCDD molecule, inhibiting its hydroxylation. The results of the access channel analysis and the distance from pig CYP1B1's heme to TCDD suggest that the metabolizing potential of pig CYP1B1 is higher than that of pig CYP1A1. However, this potential is probably not sufficiently high to considerably improve the slow TCDD biodegradation. 相似文献
983.
984.
985.
Kozioł Agata Macegoniuk Katarzyna Grela Ewa Grabowiecka Agnieszka Biernat Monika Lochyński Stanisław 《Molecular biology reports》2019,46(1):51-58
Molecular Biology Reports - Urease is an important virulence factor for a variety of pathogenic bacteria strains such as Helicobacter pylori, which colonizes human gastric mucosa, and Proteus sp.,... 相似文献
986.
987.
David S. Durica David Garza Maria A. Restrepo Monika M. Hryniewicz 《Journal of molecular evolution》1988,28(1-2):72-86
Summary The general organization and primary amino acid sequences of theS. purpuratus cytoskeletal actin genes CyIIb and CyIIIb have been determined from restriction enzyme analysis, DNA sequencing, and RNA mapping studies. As is the case with the other sea urchin cytoskeletal actin genes previously studied, the CyIIb and CyIIIb genes contain two introns that interrupt the coding DNA following codon 121 and within codon 204. An intron ending 26–27 nucleotides (nt) upstream of the initiation codon has also been localized in the 5-flanking region of both genes. The CyIIb gene, which is part of a cluster of three genes linked in the order CyI-CyIIa-CyIIb, encodes a protein that differs from CyI by a single residue and from CyIIa by three residues. The substitutions observed within this linkage group are relatively conservative changes, and pairwise comparisons between genes indicate less than 5% mismatch in nucleotide sequence within the coding region. Nucleotide sequence comparisons of 5-flanking region and intron DNA, however, indicate greater similarity between the CyI and CyIIb genes than the CyIIa gene that separates them, suggestive of a potential gene conversion event between the flanking genes in the CyI-CyIIa-CyIIb linkage.The CyIIIb gene, part of a separate cluster of two functional genes ordered CyIIIa-CyIIIb, shares little similarity outside of coding DNA with genes of the other linkage group. Although CyIIIb exhibits strong nucleotide sequence similarity outside of coding DNA with the neighboring CyIIIa gene, it differs from that gene at six codons. The CyIIIb gene encodes a protein considerably different from all cytoskeletal actins previously reported, with changes clustered in the latter 40% of the coding sequence. An 81-nt tandem duplication of the C-terminal coding region is located adjacent to the termination codon of the CyIIIb gene, a potential relic of a slipped mispairing and replication event. 相似文献
988.
C Jab?onowska D Piechocki A Wo?os 《Comparative biochemistry and physiology. B, Comparative biochemistry》1985,80(2):381-383
Carnosinase activity was determined in uterus extracts of sexually immature sows, on particular days of the oestrous cycle, and on the 20th and 30th day of pregnancy. In mature sows carnosinase activity in the uterus was on the average 4.5 times higher than in immature sows. Activity of the enzyme in the oestrous cycle increased from the zero day (first day of the heat) until 13th day, followed by a rapid decrease, reaching the lowest levels on the 17th day of the cycle (3 times lower on the average than on the zero day). On the last days of the cycle (20-21st) activity of carnosinase reached again levels similar to those of the zero day. Carnosinase activity in a uterus corner of pregnant sows (20th day of pregnancy) was over 4 times higher than in the "peak" day of the oestrous cycle (13th day), and over 12 times higher than in immature sows. Activity of the enzyme increased along with progressing pregnancy. It was found that activity of carnosinase in uterus corner of swines was related to the level of progesterone determined by other authors in the blood plasma. 相似文献
989.
Karlheinz Mann Nicolas Cerveau Meike Gummich Monika Fritz Matthias Mann Daniel J. Jackson 《Proteome science》2018,16(1):11