Author Keywords: Thermal acclimation; thermal hardening; hardening; heat hardening; cold hardening; critical thermal maxima; critical thermal minima; developmental stage; metamorphosis; tadpoles; Rana catesbeiana 相似文献
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1.
Martin A. O. H. Menke Werner Liesack Erko Stackebrandt 《Archives of microbiology》1991,155(3):263-271
The number of organization of rrn genes of two members of the order Planctomycetales, Planctomyces limnophilus and Gemmata obscuriglobus, as well as three species from other bacterial phyla, namely Thermotoga maritima, Thermus aquaticus and Verrucomicrobium spinosum were examined by Southern blot hybridization analysis of restricted DNA with labeled 16S- and 23S rRNAs. Ribotyping analysis revealed that two species contain unlinked 16S- and 23S rRNA genes. Planctomyces limnophilus possessed two unlinked rrn genes which were separated from each other by at least 4.3 kb, and Thermus aquaticus had to unlinked 16S and 23S rRNA genes, separated from each other by at least 2.5 kb. Gemmata obscuriglobus exhibited five genes for which the organization could as yet not be determined because of the complex hybridization patterns. In the other two species, rrn genes clustered in operons. Thermotoga maritima had a single gene for each rRNA species which were separated by not more than 1.5 kb, while Verrucomicrobium spinosum had four copies of probably linked 16S and 23S rRNA genes with a maximal distance between 16S and 23S rRNA genes of 1.3 kb. 相似文献
2.
3.
Size fractionation of Trypanosoma brucei DNA: localization of the 177-bp repeat satellite DNA and a variant surface glycoprotein gene in a mini-chromosomal DNA fraction 总被引:12,自引:5,他引:7 下载免费PDF全文
We have size-fractionated intact DNA from Trypanosoma brucei into a major large DNA fraction (greater than 350S) and minor middle-sized (60-250S) and small (less than 60S) DNA fractions. Large DNA contains the rRNA genes, the basic copy genes for several variant surface glycoproteins (VSGs), including one which lies near a telomer, and the expression-linked copies of the two VSG genes. The middle-sized DNA contains at least one VSG gene, but the hybridization of this fraction with probes for the conserved repetitive sequences that mark the edges of the transposed segments of VSG genes, suggests that it may contain many VSG genes. The 177-bp repeat satellite DNA is also exclusively found in this fraction. 相似文献
4.
Wilhelm Menke 《Protoplasma》1959,51(1):127-130
5.
We have broadly defined the DNA regions regulating esterase6 activity in
several life stages and tissue types of D. melanogaster using P-
element-mediated transformation of constructs that contain the esterase6
coding region and deletions or substitutions in 5' or 3' flanking DNA.
Hemolymph is a conserved ancestral site of EST6 activity in Drosophila and
the primary sequences regulating its activity lie between -171 and -25 bp
relative to the translation initiation site: deletion of these sequences
decrease activity approximately 20-fold. Hemolymph activity is also
modulated by four other DNA regions, three of which lie 5' and one of which
lies 3' of the coding region. Of these, two have positive and two have
negative effects, each of approximately twofold. Esterase6 activity is
present also in two male reproductive tract tissues; the ejaculatory bulb,
which is another ancestral activity site, and the ejaculatory duct, which
is a recently acquired site within the melanogaster species subgroup.
Activities in these tissues are at least in part independently regulated:
activity in the ejaculatory bulb is conferred by sequences between -273 and
-172 bp (threefold decrease when deleted), while activity in the
ejaculatory duct is conferred by more distal sequences between -844 and
-614 bp (fourfold decrease when deleted). The reproductive tract activity
is further modulated by two additional DNA regions, one in 5' DNA (-613 to
-284 bp; threefold decrease when deleted) and the other in 3' DNA (+1860 to
+2731 bp; threefold decrease when deleted) that probably overlaps the
adjacent esteraseP gene. Collating these data with previous studies
suggests that expression of EST6 in the ancestral sites is mainly regulated
by conserved proximal sequences while more variable distal sequences
regulate expression in the acquired ejaculatory duct site.
相似文献
6.
In earlier investigations, it has been demonstrated that Pseudocercosporella herpotrichoides (Fron) Deighton is capable of producing pectolytic and cellulolytic enzymes as well as hemicellulases in vitro. The investigation of enzyme activity in extracts from wheat plants infected with P. herpotrichoides (isolates 21e and R6) and from non-infected plants revealed the activity of the following enzymes: pectin methylesterase (PME), polymethylgalacturonase (PMG), pectin lyase (PL), carboxymethylcellulase (CMCase), xylanase and arabanase. Compared to non-infected plants, the enzyme activity in infected plants was considerably higher; in some experiments, only traces of enzyme activity could be found in control plants. The difference in the enzyme activity in infected as compared to non-infected plants was, in most cases, statistically significant, especially beginning at the end of the second week after inoculation.
The enzyme activity depended on the temperature during plant cultivation; with the exception of pectin methylesterase (PME), the activity of all investigated enzymes increased with temperature and the highest activity was found in plants grown at 20°C. The highest PME activity was measured in plants grown at 10°C; the activity of this enzyme was generally lower at 15 and 20°C. 相似文献
The enzyme activity depended on the temperature during plant cultivation; with the exception of pectin methylesterase (PME), the activity of all investigated enzymes increased with temperature and the highest activity was found in plants grown at 20°C. The highest PME activity was measured in plants grown at 10°C; the activity of this enzyme was generally lower at 15 and 20°C. 相似文献
7.
Nucleotide variation at the hypervariable esterase 6 isozyme locus of Drosophila simulans 总被引:2,自引:0,他引:2
Esterase 6 (Est-6/EST6) is polymorphic in both Drosophila melanogaster and
D. simulans for two common allozyme forms, as well as for several other
less common variants. Parallel latitudinal clines in the frequencies of the
common EST6-F and EST6-S allozymes in these species have previously been
interpreted in terms of a shared amino acid polymorphism that distinguishes
the two variants and is subject to selection. Here we compare the sequences
of four D. simulans Est-6 isolates and show that overall estimates of
nucleotide heterozygosity in both coding and 5' flanking regions are more
than threefold higher than those obtained previously for this gene in D.
melanogaster. Nevertheless, the ratio of replacement to exon silent-site
polymorphism in D. simulans is less than the ratio of replacement to silent
divergence between D. simulans and D. melanogaster, which could be the
result of increased efficiency of selection against replacement
polymorphisms in D. simulans or to divergent selection between the two
species. We also find that the amino acid polymorphisms separating EST6- F
and EST6-S in D. simulans are not the same as those that separate these
allozymes in D. melanogaster, implying that the shared clines do not
reflect shared molecular targets for selection. All comparisons within and
between the two species reveal a remarkable paucity of variation in a
stretch of nearly 400 bp immediately 5' of the gene, indicative of strong
selective constraint to retain essential aspects of Est-6 promoter
function.
相似文献
8.
S J Usala J B Menke T L Watson F E Wondisford B D Weintraub J Bérard W E Bradley S Ono O T Mueller B B Bercu 《Molecular endocrinology (Baltimore, Md.)》1991,5(3):327-335
Different point mutations have been identified in the T3-binding domain of the c-erbA beta thyroid hormone receptor gene that are associated with variant phenotypes of generalized thyroid hormone resistance (GTHR). In most cases of GTHR, heterozygotes are affected; a single mutant allele results in the inhibition of the function of normal thyroid hormone receptors. We report here a novel genetic abnormality, a 3-basepair (bp) deletion in the T3-binding domain of the beta-receptor in a kindred, S, with GTHR. One patient, S1, was the product of a consanguineous union of two heterozygotes and was homozygous for this defect. Heterozygotes from kindred S harbored a CAC deletion at nucleotides 1295-1297, which resulted in the deduced loss of amino acid residue threonine at codon 332, and they displayed elevated free T4 levels and inappropriately normal TSH levels characteristic of other kindreds with GTHR. However, patient S1, who had two mutant alleles, had markedly elevated TSH and free T4 levels and displayed profound abnormalities in brain development and linear growth. A fibroblast c-erbA beta cDNA extending from codon 175 to stop codon 457 was cloned from patient S1, sequenced, and used to create a full-length mutant cDNA. The kindred S mutant receptor was synthesized in vitro and did not bind T3. This mutant receptor did bind with similar avidity as the wild-type human beta-receptor to thyroid hormone response elements of the human TSH beta (-12 to 43 bp) and rat GH (-188 to -160 bp) genes. Kindred S showed the effect in man of heterozygous and homozygous expression of a dominant negative form of c-erbA beta. 相似文献
9.
1. 1.|Critical thermal maxima (CTMax) and minima (CTMin) were measured to evalute thermal hardening in Rana catesbeiana.
2. 2.|Tadpoles show heat hardening and CTMax acclimation, and both responses are influenced by developmental stage.
3. 3.|The first evidence of cold hardening in vertebrates is reported here.
4. 4.|Heat hardening significantly reduces cold tolerance, but there is otherwise no evidence of a cross-hardening effect.
10.