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1.
2.
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
3.
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
4.
Anthropogenic impacts from urbanization, deforestation, and agriculture have degraded the riparian margins of waterways worldwide. In New Zealand, such impacts have caused changes in native vegetation, enhanced invasion by exotic grasses, and altered river bank morphology. One consequence has been a great reduction in obligate spawning habitat of a diadromous fish, Galaxias maculatus. Juvenile G. maculatus comprise a culturally important fishery that has been considerably reduced over recent decades. Rehabilitation of riparian vegetation needed for spawning is relatively straightforward, but slow. We hypothesized that artificial spawning habitats could accelerate restoration of fish egg production by creating an environment that would support at least the same density and survival of eggs as non‐impacted vegetation. We tested three artificial devices (straw bales, straw tubes, and moss tubes) in degraded and intact sites. Eggs were laid in all of these with numbers and survival usually exceeding that in riparian grasses. Where habitat was degraded, artificial spawning habitats yielded up to 10,000 eggs compared to none in nearby natural spawning habitat. The ground‐level environment of artificial habitat was similar to that of intact vegetation in buffering ambient temperature and humidity fluctuations. Crucial properties of the artificial habitats were (1) shelter to provide shade and hold moisture; (2) accessibility to allow adult fish to deposit and fertilize eggs; and (3) robustness to provide reliable surfaces and protection for the eggs during their development. We show that artificial spawning habitats are a viable short‐term alternative to rehabilitating spawning habitat while legacy effects abate and riparian vegetation recovers. 相似文献
5.
6.
Rod and cone photoreceptors project from the outer retinal surface into a
carbohydrate-rich interphotoreceptor matrix (IPM). Unique IPM
glycoconjugates are distributed around rods and cones. Wheat germ
agglutinin (WGA) strongly decorates the rod matrix domains and weakly
decorates the cone matrix domains. This study characterizes the major
WGA-binding glycoprotein in the human IPM, which we refer to as SPACR
(sialoprotein associated with cones and rods). SPACR, which has a molecular
weight of 147 kDa, was isolated and purified from the IPM by lectin
affinity chromatography. A polyclonal antibody to SPACR was prepared that
colocalizes in tissue preparations with WGA-binding domains in the IPM.
Sequential digestion of SPACR with N- and O- glycosidases results in a
systematic increase in electrophorectic mobility, indicating the presence
of both N- and O-linked glycoconjugates. Complete deglycosylation results
in a reduction in the relative molecular mass of SPACR by about 30%.
Analysis of lectin binding allowed us to identify some of the structural
characteristics of SPACR glycoconjugates. Treatment with neuraminidase
exposes Galbeta1- 3GalNAc disaccharide as indicated by positive peanut
agglutinin (PNA) staining, accompanied by the loss of WGA staining. Maackia
amurensis agglutinins (MAA-1 and MAA-2), specific for sialic acid in
alpha2-3 linkage to Gal, bind SPACR, while Sambucus nigra agglutinin (SNA),
specific for alpha2-6 linked sialic acid, does not, indicating that the
dominant glycoconjugate determinant on SPACR is the O-linked carbohydrate,
NeuAcalpha2-3Galbeta1-3GalNAc. The abundance of sialic acid in SPACR
suggests that this glycoprotein may contribute substantially to the
polyanionic nature of the IPM. The carbohydrate chains present on SPACR
could also provide sites for extensive crosslinking and participate in the
formation of the ordered IPM lattice that surrounds the elongate
photoreceptors projecting from the outer retinal surface.
相似文献
7.
The recent structure determinations of the mammalian effector enzyme adenylyl cyclase reveal the structure of its catalytic core, provide new insights into its catalytic mechanism and suggest how diverse signaling molecules regulate its activity. 相似文献
8.
9.
Polymorphisms in the ovine myostatin gene (MSTN) and their association with growth and carcass traits in New Zealand Romney sheep 总被引:1,自引:0,他引:1
J. G. H. Hickford R. H. Forrest H. Zhou Q. Fang J. Han C. M. Frampton A. L. Horrell 《Animal genetics》2010,41(1):64-72
Myostatin is a regulator of myogenesis and has been implicated in the regulation of adiposity and in controlling the structure and function of tendons. Polymerase Chain Reaction Single-Stranded Conformational Polymorphism (PCR-SSCP) analysis of intron-1 was used to identify five variants (designated A-E) of the myostatin gene ( MSTN ). The effect of this genetic variation on growth and carcass traits was investigated in 517 Romney male lambs from 17 sire-lines, born on a South Island New Zealand farm. General linear mixed effect models revealed that the presence of allele A in a lamb's genotype was associated with decreased leg, loin and total yield of lean meat, whereas the presence of allele B was associated with increased loin yield and proportion loin yield (loin yield divided by total yield expressed as percentage). The effect of the number of allele copies present was investigated, and it was found that the absence of A , or the presence of two copies of B , was associated with increased mean leg yield, loin yield and total yield. Two copies of B were also associated with a decrease in proportion of shoulder yield, whereas two copies of A were associated with a decrease in proportion of loin yield. Associations with allele C were not detected. No associations of MSTN variation with birth weight, weaning weight, pre-weaning growth rate, draft age and hot carcass weight (H-W) were detected. These results suggest that variation in ovine MSTN is associated with meat production, but not birth weight or growth rate in New Zealand Romney sheep. 相似文献
10.
JG Hansen W Gao J Dupuis GT O’Connor W Tang M Kowgier A Sood SA Gharib LJ Palmer M Fornage SR Heckbert BM Psaty SL Booth SUNLIGHT Consortium Patricia A Cassano 《Respiratory research》2015,16(1)