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1.
V. Cavaliere S. Spanò D. Andrenacci L. Cortesi G. Gargiulo 《Molecular & general genetics : MGG》1997,254(3):231-237
The Drosophila vitelline membrane protein gene VM32E is expressed according to a precise temporal and spatial program in the follicle cells. Results from germ line transformation
experiments using different fragments of the −465/−39 VM32E region fused to the hsp/lacZ reporter gene revealed that the region −348/−39 is sufficient to confer the wild-type expression pattern. Within this segment,
distinct cis-regulatory elements control VM32E expression in ventral and dorsal follicle cells. The region between −135/−113 is essential for expression of the VM32E gene in the ventral columnar follicle cells. Expression in the dorsal domain requires the two regions −348/−254 and −118/−39.
Furthermore, the region −253/−119 appears to contain a negative element that represses gene activity in anterior centripetal
cells. We suggest that the expression of the VM32E gene throughout the follicular epithelium is controlled by specific cis-regulatory elements acting in distinct spatial domains and following a precise developmental program.
Received: 22 October 1996 / Accepted: 14 November 1996 相似文献
2.
Evidence for NO-dependent vasodilation in the trout (Oncorhynchus mykiss ) coronary system 总被引:1,自引:0,他引:1
T. Mustafa C. Agnisola J. K. Hansen 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(2):98-104
The effects of l-arginine, and its analogues N
ω-nitro-l-arginine methyl ester and N
ω-nitro-l-arginine on vascular resistance were investigated in the intact coronary system of an isolated non-working trout heart preparation.
l-Arginine, at 10–8 mol · l–1induced a slight vasodilatory effect (max 10%). N
ω-nitro-l-arginine methyl ester and N
ω-Nitro-l-arginine in the range 10–8–10–4 mol · l–1 caused dose-dependent increases in coronary resistance. The vasodilatory action of l-arginine was abolished when the preparation was pretreated with 10–4 mol · l–1
N
ω-nitro-l-arginine or N
ω-nitro-l-arginine methyl ester. Nitroprusside alone at 1 mmol · l–1 induced a maximum vasodilation (30%) of the coronary system. Methylene blue a known inhibitor of guanylate cyclase, induced
a strong vasoconstriction (already significant at 10–5 mol · l–1) and was able to overcome the vasodilative effect of nitroprusside. The endothelial nitric oxide agonists acetylcholine and
serotonin, established in mammalian vessels, also mediate vasodilation in trout coronary system. In 50% of preparations, acetylcholine
induced a biphasic response with vasodilation at low concentration (max 15% at 10–8 mol · l–1). Serotonin displayed a dose-response vasodilation in the range 10–8–10–4 mol · l–1 (max 20%). These vasodilative effects were reduced or abolished by 10–4 mol · l–1
l-NA. These data support the existence of NO-mediated vasodilation mechanisms in the trout coronary system.
Accepted: 1 July 1996 相似文献
3.
4.
Ralph Beneke Katharina Meyer 《European journal of applied physiology and occupational physiology》1997,75(3):246-251
The effect of a 3-week exercise programme on performance and economy of walking was analysed in 16 male patients with chronic
heart failure [mean age 51.8 (SD 6.9) years, height 174.9 (SD 6.3) cm, body mass 75.3 (SD 11.5) kg, ejection fraction 20.8
(SD 5.0)%]. They were submitted to a cardiopulmonary exercise test on a cycle ergometer and a 6-min walking test on a treadmill
before and after the period of exercise training. The training programme consisted of interval cycle (five times a week for
15 min), and treadmill ergometer training (three times a week for 10 min) at approximately 70% cycling peak oxygen uptake
(O2peak) and supplementary exercises (three times a week for 20 min). Compared to the pre values cycling O2peak [11.9 (SD 2.9) vs 14.0 (SD 2.3) ml · kg–1 · min–1], maximal self paced walking speed [0.68 (SD 0.33) vs 1.16 (SD 0.30) m · s–1], and net walking power [2.16 (SD 0.89) vs 2.73 (SD 0.91) W · kg–1] had increased (P < 0.01) while net energy cost [3.31 (SD 0.66) vs 2.33 (SD 0.38) J · kg–1 · m–1] had decreased (P < 0.001) after the training period. Approximately 42% of the increase of walking speed resulted from a higher walking power
output, whereas approximately 58% corresponded to a positive effect on walking economy. The improvement in walking economy
was a function of an increase in walking velocity itself and a result of a more efficient walking technique. These results
would indicate that in patients with marked exercise intolerance, adequate exercise training programmes could contribute to
favourable metabolic changes with positive effects on the economy of motion.
Accepted: 29 August 1996 相似文献
5.
6.
A. D. Blest Sally Stowe 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1997,180(4):347-355
(1) In vitro retinas of a crab, Leptograpsus, were treated with a phospholipase inhibitor, manoalide, or a G-protein activator, Mas-7. Both drugs address early stages
of the phototransduction cascade. (2) Manoalide inhibited the light-dependent reduction of rhabdoms during the `day' phase
of the light cycle, but did not induce rhabdom overgrowth. Following a period of darkness manoalide failed to affect the diminution
of illuminated rhabdoms. (3) The diminution of rhabdoms that follows photoreceptor depolarisation induced by 100 mmol · l−1 K+ in darkness was not affected by 2␣μmol · l−1 manoalide. (4) When retinas in the `night' phase were treated with Mas-7 in darkness, rhabdom diameters were augmented, concurrently
with endocytosis of photoreceptor plasma membranes. (5) The results of combining manoalide and Mas-7 with actinomycin D, U-57908
or okadaic acid, drugs used in previous studies to manipulate steps notionally lower in the transduction cascade, lead to
a hypothetical model for the regulation of phototransductive membrane turnover by arthropods.
Accepted: 3 October 1996 相似文献
7.
We have identified a new En/Spm-like transposable element, Tdc1, in the 5′ flanking region of a phenylalanine ammonia-lyase gene (gDcPAL1) that is normally induced by transferring cells of carrot suspension cultures to fresh liquid medium (transfer or dilution
effect). The initial integration into gDcPAL1 occurred more than 4 years after culture initiation. Tdc1 was first detected in gDcPAL1 genomic clones of a genomic library made from cells of the same cultured cell line 7 years after its initiation and thus
following repeated subculturing. Twelve years after initiation, about 5–10% of the cells had Tdc1 inserted into the gDcPAL1 gene, indicating that Tdc1 insertion into gDcPAL1 occurred in one (or more) cell(s) during the first 4–7 years of subculturing. These mutant cells did not disappear during
numerous passages; instead the proportion of cells having this Tdc1 inserted into gDcPAL1 has been increasing over the last 5 years. The promoter activity and the inducibility by transfer/dilution of the gDcPAL1 gene harboring Tdc1 is reduced relative to wild type. Finally, we show that insertion of a transposable element is one of the mechanisms that
can cause variation of plant cell cultures during repeated subculture.
Received: 11 October 1996 / Accepted: 27 December 1996 相似文献
8.
Indolepyruvate ferredoxin oxidoreductase (IOR) catalyzes the oxidative decarboxylation of arylpyruvates. Gene cloning and
sequencing analysis of the IOR gene from the hyperthermophilic archaeon Pyrococcus sp. KOD1 was performed. Two genes, iorA and iorB, encoding α and β subunits of IOR were found to be tandemly arranged, which suggests that gene expression is translationaly
coupled. Sequence analysis showed the C-terminal region of the α subunit to have a typical ferredoxin-type [4Fe-4S] cluster
motif (CXXCXXCXXCXXXCP), which is similar to that present in the δ subunits of other oxidoreductases such as pyruvate ferredoxin
oxidoreductase (POR) and 2-ketoisovalerate ferredoxin oxidoreductase (VOR). We suggest that the α subunit of KOD1-IOR has
a mosaic structure composed of features characteristic of the α, β and δ subunits from POR and VOR. KOD1-IOR was overproduced
in anaerobically incubated Escherichia coli cells and the crude enzyme was extracted under anaerobic conditions. The optimal temperature for activity of recombinant
IOR was 70° C and the half-life of this enzyme in the presence of air was 15 min at 25° C.
Received: 25 September 1996 / Accepted: 20 December 1996 相似文献
9.
Seasonal changes in fatty acid composition associated with cold-hardening in third instar larvae of Eurosta solidaginis 总被引:1,自引:1,他引:0
Valerie A. Bennett Nancy L. Pruitt Richard E. Lee Jr. 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(4):249-255
Third-instar larvae of the goldenrod gall fly Eurosta solidaginis (Diptera: Tephritidae) survive extended periods in winter during which tissue water is frozen. Both low temperature and reduced
water activity during freezing present challenges for the structural integrity of cellular lipids. Fatty acids of both phospholipids
and triacylglycerols from fat body cells of E. solidaginis were analyzed throughout fall and early winter, a period that encompasses the acquisition of freeze-tolerance, to determine
if adaptations to freezing include changes in fatty acid unsaturation. The five most abundant fatty acids from both fractions
were (in decreasing order) oleic (40–65%), palmitoleic (18–20%), palmitic (12–17%), linoleic (5–10%), and stearic acids (4 –7%).
This represents a typical complement of Dipteran fatty acids, although oleic acid levels were higher in E. solidaginis than those reported from other Dipterans (˜28%; Downer 1985). From September to November, monounsaturates increased from
59 to 70% in phospholipids at the expense of saturated fatty acids (25% –20%) suggesting activation of a Δ9-desaturase enzyme. These changes resulted in an increase in the ratio of unsaturated to saturated fatty acids (U/S) from
3.0 to 4.2, although there was no change in the average number of double bonds per fatty acid (unsaturation index, UI ≈ 1.2
in phospholipids and 0.9 in triacylglycerols throughout the season). These changes were temporally correlated to decreasing
ambient temperatures and increasing larval and fat body cell freeze-tolerance.
Accepted: 31 October 1996 相似文献
10.
11.
Sex-peptide (SP), which is secreted by the accessory gland of Drosophila males, is transferred to the female during copulation, thereby reducing her sexual appetite (receptivity to males) and stimulating
ovulation/oviposition. SP is known to be taken up into the hemolymph of mated females, but it is not clear whether there are
two separate target tissues, for behavioral changes and ovulation or only one target for both responses. We have employed
the GAL4-UAS system to express SP transgene constructs, both in different tissues and in different cellular components of
virgin females. A cytoplasmic form of SP lacking a signal sequence did not evoke any responses, even when expressed ubiquitously.
In contrast, a membrane-bound form of SP induced typical post-mating behavior, indicating that SP must be outside the cell
in order to exert its biological effects. A total of 204 randomly selected P[GAL4] enhancer-trap lines were screened for their
ability to induce SP responses in combination with the membrane-bound SP expressed under GAL4 control. Thirty-three lines
were associated with both behavioral change and stimulated ovulation. No line was associated with only one of the two responses,
implying that the SP target(s) mediating the two responses are either identical, very closely located, or present in two distinct
tissues with a common set of genetic determinants. Western blot analysis of head, thorax, and abdominal extracts revealed
that the biological activity was correlated with expression in the head fraction.
Received: 3 October 1996 / Accepted: 6 January 1997 相似文献
12.
S. J. Brown R. B. Child S. H. Day A. E. Donnelly 《European journal of applied physiology and occupational physiology》1997,75(4):369-374
Indirect indices of exercise-induced human skeletal muscle damage and connective tissue breakdown were studied following
a single bout of voluntary eccentric muscle contractions. Subjects (six female, two male), mean (SD) age 22 (2) years performed
a bout of 50 maximum voluntary eccentric contractions of the knee extensors of a single leg. The eccentric exercise protocol
induced muscle soreness (P < 0.05 Wilcoxon test), chronic force loss, and a decline in the 20:100 Hz percutaneous electrical myostimulation force ratio
[P < 0.01, repeated measures analysis of variance (ANOVA)]. Serum creatine kinase (CK) and lactate dehydrogenase (LDH) activities
were elevated (P < 0.01, repeated measures ANOVA) following the bout. The mean (SD) CK and LDH levels recorded 3 days post-exercise were 2815
(4144) IU · l–1 and 375 (198) IU · l–1, respectively. Serum alkaline phosphatase activity showed no changes throughout the study, and a non-significant increase
(P = 0.058, repeated measures ANOVA) in pyridinoline was recorded following the bout. Urinary hydroxyproline (HP) and hydroxylysine
(HL) excretion, expressed in terms of creatinine (Cr) concentration, increased after exercise (P < 0.05 and P < 0.01, respectively, repeated measures ANOVA). An increased HP:Cr was recorded 2 days post-exercise and HL:Cr was increased
above baseline on days 2, 5, and 9 post-exercise. This indirect evidence of exercise-induced muscle damage suggests that myofibre
disruption was caused by the eccentric muscle contractions. Elevated urine concentrations of indirect indices of collagen
breakdown following eccentric muscle contractions suggests an increased breakdown of connective tissue, possibly due to a
localised inflammatory response.
Accepted: 9 October 1996 相似文献
13.
R. Waugh K. McLean A. J. Flavell S. R. Pearce A. Kumar B. B. T. Thomas W. Powell 《Molecular & general genetics : MGG》1997,253(6):687-694
Retrotransposons are present in high copy number in many plant genomes. They show a considerable degree of sequence heterogeneity
and insertional polymorphism, both within and between species. We describe here a polymerase chain reaction (PCR)-based method
which exploits this polymorphism for the generation of molecular markers in barley. The method produces amplified fragments
containing a Bare–1-like retrotransposon long terminal repeat (LTR) sequence at one end and a flanking host restriction site
at the other. The level of polymorphism is higher than that revealed by amplified fragment length polymorphism (AFLP) in barley.
Segregation data for 55 fragments, which were polymorphic in a doubled haploid barley population, were analysed alongside
an existing framework of some 400 other markers. The markers showed a widespread distribution over the seven linkage groups,
which is consistent with the distribution of the Bare–1 class of retrotransposons in the barley genome based on in situ hybridisation
data. The potential applicability of this method to the mapping of other multicopy sequences in plants is discussed.
Received: 17 July 1996 / Accepted: 20 September 1996 相似文献
14.
Light response characteristics of a morphologically diverse group of southern hemisphere conifers as measured by chlorophyll fluorescence 总被引:5,自引:0,他引:5
Unlike northern hemisphere conifer families, the southern family, Podocarpaceae, produces a great variety of foliage forms
ranging from functionally broad-, to needle-leaved. The production of broad photosynthetic surfaces in podocarps has been
linked qualitatively to low-light-environments, and we undertook to assess the validity of this assumption by measuring the
light response of a morphologically diverse group of podocarps. The light response, as apparent photochemical electron transport
rate (ETR), was measured by modulated fluorescence in ten species of this family and six associated species (including five
Cupressaceae and one functionally needle-leaved angiosperm) all grown under identical glasshouse conditions. In all species,
ETR was found to increase as light intensity increased, reaching a peak value (ETRmax) at saturating quantum flux (PPFDsat), and decreasing thereafter. ETRmax ranged from 217 μmol electrons · m−2 · s−1 at a PPFDsat of 1725 μmol photons · m−2 · s−1 in Actinostrobus acuminatus to an ETR of 60 μmol electrons · m−2 · s−1 at a PPFDsat of 745 μmol electrons · m−2 · s−1 in Podocarpus dispermis. Good correlations were observed between ETRmax and both PPFDsat and maximum assimilation rate measured by gas-exchange analysis. The effective quantum yield at light saturation remained
constant in all species with an average value of 0.278 ± 0.0035 determined for all 16 species. Differences in the shapes of
light response curves were related to differences in the response of non-photochemical quenching (q
n), with q
n saturating faster in species with low PPFDsat. Amongst the species of Podocarpaceae, the log of average shoot width was well correlated with PPFDsat, wider leaves saturating at lower light intensities. This suggests that broadly flattened shoots in the Podocarpaceae are
an adaptation to low light intensity.
Received: 15 April 1996 / Accepted: 30 September 1996 相似文献
15.
A transposable element, Flipper, was isolated from the phytopathogenic fungus Botrytis cinerea. The element was identified as an insertion sequence within the coding region of the nitrate reductase gene. The Flipper
sequence is 1842 bp long with perfect inverted terminal repeats (ITRs) of 48 bp and an open reading frame (ORF) of 533 amino
acids, potentially encoding for a transposase; the element is flanked by the dinucleotide TA. The encoded protein is very
similar to the putative transposases of three elements from other phytopathogenic fungi, Fot1 from Fusarium oxysporum, and Pot2 and MGR586 from Magnaporthe grisea. The number of Flipper elements in strains of B. cinerea varied from 0 to 20 copies per genome. Analysis of the descendants of one cross showed that the segregation ratio of Flipper
elements was 2:2 and that the copies were not linked.
Received: 4 December 1996 / Accepted: 21 January 1997 相似文献
16.
《Molecular & general genetics : MGG》1997,256(3):239-251
The gene cluster (ery) governing the biosynthesis of the macrolide antibiotic erythromycin A by Saccharopolyspora erythraea contains, in addition to the eryA genes encoding the polyketide synthase, two regions containing genes for later steps in the pathway. The region 5′ of eryA, and lying between eryA and the gene eryK, which is known to encode the C-12 hydroxylase, has been sequenced and shown to contain seven additional open reading frames
(ORFs 13–19). On the basis of sequence similarities, roles are proposed for several of these ORFs in the biosynthesis of the
deoxysugar mycarose and the deoxyaminosugar desosamine. A chromosomal mutant carrying a deletion in ORF15 has been constructed
and shown to accumulate 3-O-mycarosyl-erythronolide B, as expected for an eryC mutant. Similarly, a chromosomal mutant carrying a deletion in ORF16 has been constructed and shown to accumulate erythronolide
B, as expected for an eryB mutant.
Received: 10 March 1997 / Accepted: 12 June 1997 相似文献
17.
To isolate genes that negatively regulate cell growth, we constructed a galactose-inducible expression library with partially
digested Saccharomyces cerevisiae genomic DNA fragments inserted downstream of the GAL10 promoter. In all, 240 000 yeast transformants were screened for lethality on galactose medium. From 17 such transformants
identified, 16 nonoverlapping DNA sequences were obtained. Restriction mapping and determination of DNA sequences adjacent
to the GAL10 promoter indicated that the inserts encoded part or all of the URA2, RBP1, TPK3, SAC7, BOI1, and BNI1 genes, and also open reading frames (ORFs) from chromosomes IV, V, IX, XI, and XIII. Some of the identified sequences lacked
the amino-terminal sequences of the ORFs, suggesting that truncated forms of the proteins might be necessary for growth inhibition.
The sequence of the pGA108 insert was highly homologous to the telomeric X-element and contained an ARS consensus sequence, suggesting a possible growth inhibitory effect of an RNA molecule. Overexpression of the BNI1ΔN and BOI1ΔN genes, which lacked amino-terminal sequences, was associated with phenotypes similar to those of mutants defective in bud
formation. Overexpression of the GIN4 and GIN12 sequences induced elongated buds and a G2/M arrest-like phenotype, respectively.
The phenotypes induced by the overexpression of our cloned sequences could result from either a dominant-positive or a dominant-negative
effect and, unexpectedly, in one case from an effect of an RNA.
Received: 3 June 1996 / Accepted: 1 October 1996 相似文献
18.
S. B. Chaplin M. M. Munson S. T. Knuth 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1997,167(3):197-203
The effect of various activity regimes on metabolism of pigeon pectoralis was examined by measurement of blood lactate following
exercise, total lactate dehydrogenase activity of pectoral muscle, and proportions of specific isoenzymes of pectoral muscle
lactate dehydrogenase. Sprint-trained birds had the highest pectoral muscle lactate dehydrogenase activity (1409 IU · g−1 wet tissue), while endurance-trained birds had the highest peak lactate levels (287 mg · dl−1, extrapolated from decay curves) and fastest half-time of the lactate response (4.8 min) following exercise, but the lowest
lactate dehydrogenase activity (115 IU · g−1 wet tissue). Immobilization of one wing for 3 weeks following endurance training produced a marked increase in lactate dehydrogenase
activity of the immobilized muscle, compared to that in the contralateral pectoralis and endurance-trained muscle. Aerobic
forms of the lactate dehydrogenase enzyme (that favor conversion of lactate to pyruvate) predominated in pectoral muscle of
endurance-trained birds, while cage-confined birds exhibited primarily the anaerobic isoenzymes. These results demonstrate
that conversion of pectoral muscle lactate dehydrogenase isoenzymes, total lactate dehydrogenase activity, and half-time of
lactate response after exercise is dependent on activity regime in pigeons. In this respect, pigeon pectoral muscle responds
to training and disuse in a manner similar to that of mammalian skeletal muscle.
Accepted: 10 September 1996 相似文献
19.
SulA is induced in Escherichia coli by the SOS response and inhibits cell division through interaction with FtsZ. To determine which region of SulA is essential
for the inhibition of cell division, we constructed a series of N-terminal and C-terminal deletions of SulA and a series of
alanine substitution mutants. Arginine at position 62, leucine at 67, tryptophan at 77 and lysine at 87, in the central region
of SulA, were all essential for the inhibitory activity. Residues 3–27 and the C-terminal 21 residues were dispensable for
the activity. The mutant protein lacking N-terminal residues 3–47 was inactive, as was that lacking the C-terminal 34 residues.
C-terminal deletions of 8 and 21 residues increased the growth-inhibiting activity in lon
+ cells, but not in lon
− cells. The wild-type and mutant SulA proteins were isolated in a form fused to E. coli maltose-binding protein, and tested in vitro for sensitivity to Lon protease. Lon degraded wild-type SulA and a deletion
mutant lacking the N-terminal 93 amino acids, but did not degrade the derivative lacking 21 residues at the C-terminus. Futhermore,
the wild-type SulA and the N-terminal deletion mutant formed a stable complex with Lon, while the C-terminal deletion did
not. MBP fused to the C-terminal 20 residues of SulA formed a stable complex with, but was not degraded by Lon. When LacZ
protein was fused at its C-terminus to 8 or 20 amino acid residues from the C-terminal region of SulA the protein was stable
in lon
+ cells. These results indicate that the C-terminal 20 residues of SulA permit recognition by, and complex formation with,
Lon, and are necessary, but not sufficient, for degradation by Lon.
Received: 8 October 1996 / Accepted: 27 November 1996 相似文献