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11.
12.
Intraspecific variation in reproductive physiology and egg quality in the European Starling Sturnus vulgaris 总被引:1,自引:0,他引:1
Egg mass shows large intraspecific variation in birds and is repeatable within individuals. The mechanisms underlying this variation are unknown. We hypothesized that measures of egg quality (the mass of yolk protein, yolk lipid, and albumen protein) would be positively correlated with the plasma pools of the yolk precursor vitellogenin, and the masses of the oviduct, metabolic machinery (liver, heart, lungs, kidneys, gizzard, small intestine and pancreas), and endogenous stores of protein and lipid. We tested these predictions in European Starlings Sturnus vulgaris collected at the peak of egg production effort. In contrast to our predictions, both yolk protein and yolk lipid were negatively correlated with plasma vitellogenin levels. Albumen protein was positively related to oviduct mass, but other aspects of body composition failed to explain variation in egg quality. Hence, while we observed correlations between egg composition and peripheral systems (circulating precursor pools and the oviduct), we found no evidence that egg quality is determined by more general processes, i.e., the supply and processing of nutrients. 相似文献
13.
Aminoglycoside suppression at UAG, UAA and UGA codons in Escherichia coli and human tissue culture cells 总被引:6,自引:0,他引:6
Robin Martin Anne E. Mogg Louise A. Heywood Lars Nitschke Julian F. Burke 《Molecular & general genetics : MGG》1989,217(2-3):411-418
Summary We have compared the suppression of nonsense mutations by aminoglycoside antibiotics inEscherichia coli and in human 293 cells. Six nonsense alleles of the chloramphenicol acetyl transferase (cat) gene, in the vector pRSVcat, were suppressed by growth in G418 and paromomycin. Readthrough at UAG, UAA and UGA codons was monitored with enzyme assays
for chloramphenicol acetyl transferase (CAT), in stably transformed bacteria and during transient expression from the same
plasmid in human 293 tissue culture cells. We have found significant differences in the degree of suppression amongst three
UAG codons and two UAA codons in different mRNA contexts. However, the pattern of these effects are not the same in the two
organisms. Our data suggest that context effects of nonsense suppression may operate under different rules inE. coli and human cells. 相似文献
14.
C Julian M C Tordo G Macquart-Moulin J P Moatti F Giraud S Aymé 《Social biology》1989,36(3-4):240-247
A study of factors influencing genetic counseling attendance rate has been conducted in the Bouches-du-Rh?ne area, in the south of France. In this area, a birth defects monitoring system (Eurocat n. 22) annually covers 23,000 births. All the genetic services are delivered by only one genetic center located in Marseilles, and the data collected are computerized. The comparison of these two data bases gives an opportunity to estimate the rate of genetic counseling attendance after the occurrence of an affected stillbirth or live birth. Among the parents of 358 infants born in 1983-84 in this area with a pathology requiring genetic counseling, 226 (63 per cent) attended the Genetic Center within the first year after birth. The rate of attendance is statistically higher (p less than 0.01) for the parents who had a stillbirth (78 per cent) than for those who had a live birth (57 per cent). It is also higher (p less than 0.01) for the Marseilles maternities group (68 per cent) than for the group outside Marseilles (50 per cent). The referral delays are also analyzed according to malformation etiology and to viability of the child by the eighth day of life. Besides evaluating a particular genetic center's effectiveness in diffusing information to the public concerned, this work shows that couples' request is strongly dependent on a psychological need. 相似文献
15.
Summary The accumulation of interferon (IFN) -2 in transformed strains of Escherichia coli and Methylophilus methylotrophus was greater at 25° C than at 37° C. Interferon -2 catabolism was followed by measuring the change in IFN titre (measured immunoreactively) with time at temperatures between 25° C and 37° C in chloramphenicol-treated cells. The IFN -2 titre remained constant at 29° C and below, while at higher temperatures the titres declined. The t
1/2 values for IFN -2 decreased with increasing incubation temperature. Pulse-chase studies using [35S]methionine, sodium dodecyl sulphate-gel electrophoresis and autoradiography demonstrated that IFN -2 was subjected to degradation at 37° C while at 25° C it was stable. It is proposed that the susceptibility of IFN -2 to degradation in both E. coli and M. methylotrophus is affected by incubation temperature and 30° C may be a transition temperature above which the conformation of the molecule is recognised by the bacterial proteases. 相似文献
16.
Effects of DNase production, plasmid size, and restriction barriers on transformation of Vibrio cholerae by electroporation and osmotic shock 总被引:14,自引:0,他引:14
Hilda Marcus Julian M. Ketley James B. Kaper Randall K. Holmes 《FEMS microbiology letters》1990,68(1-2):149-154
Attempts to transform wild type strains of V. cholerae with plasmid DNA by traditional osmotic shock methods were not successful. A mutant of V. cholerae that was deficient in extracellular DNase was transformed with plasmid DNA by osmotic shock, demonstrating directly that extracellular DNase is a major barrier to transformation of V. cholerae. Transformation of wild type and DNase-negative strains of V. cholerae was accomplished by electroporation. Efficiency of transformation by electroporation increased with field strength, decreased with plasmid size, and was relatively insensitive to changes in the electrolyte composition of the buffer as long as isotonic sucrose was present. Host-controlled modification/restriction systems also affected transformation efficiency in V. cholerae. 相似文献
17.
Julian J. Dodson 《Environmental Biology of Fishes》1988,23(3):161-182
Synopsis Fish migration may be viewed as the product of two processes; the selection and tracking of optimal environmental conditions
through time and space, and the use of predictive information about environmental structure to bias movements towards a goal.
The establishment and maintenance of directional bias is based on the interaction of experience and instinct. The preoccupation
of much fish orientation research with innate fixed patterns of behavior on one hand and hydrodynamics on the other has led
us to underestimate the possibility that orientation is a flexible process relying on developmental sequences, calibration
of the motor-sensory interaction based on experience and the learning of environmental pattern. Evidence illustrating how
experience and learning may influence the direction of movement and how the goal is recognized is presented according to two
general categories: (a) imprinting and early experience and (b), spatial learning, including the social transmission of migratory
routes and directions. In the first category, the olfactory hypothesis of salmon homing is briefly reviewed and new data presented
describing olfactory imprinting in Atlantic salmon,Salmo salar. In the second category, evidence is presented demonstrating the modifiability of sun-compass orientation and the ability
of some fish species to learn the spatial distribution of landmarks. The role of social transmission in the migration of coral
reef fishes is reviewed. The possible role of these learning phenomena in the formation of familiar area maps, route-based
and location-based navigation and the critical distance factor is considered. The relationship between life history and the
nature of learning in migratory orientation is discussed 相似文献
18.
Agnes Janoshazi David M. Ojcius Bruce Kone Julian L. Seifter A. K. Solomon 《The Journal of membrane biology》1988,103(2):181-189
Summary A membrane protein that is immunochemically similar to the red cell anion exchange protein, band 3, has been identified on the basolateral face of the outer medullary collecting duct (MCD) cells in rabbit kidney. In freshly prepared separated rabbit MCD cells, M.L. Zeidel, P. Silva and J.L. Seifter (J. Clin. Invest.
77:1682–1688, 1986) found that Cl–/HCO
3
-
exchange was inhibited by the stilbene anion exchange inhibitor, DIDS (4,4-diisothiocyano-2,2-disulfonic stilbene), with aK
1 similar to that for the red cell. We have measured the binding affinities of a fluorescent stilbene inhibitor, DBDS (4,4-dibenzamido-2,2-disulfonic stilbene), to MCD cells in 28.5 mM citrate and have characterized both a high-affinity site (K
1
s
=93±24 mM) and a lower affinity site (K
2
s
=430±260 nM), which are closely similar to values for the red cell of 110±51 nM for the high-affinity site and 980±200 nM for the lower affinity site (A.S. Verkman, J.A. Dix & A.K. Solomon,J. Gen. Physiol.
81:421–449, 1983). When Cl– replaces citrate in the buffer, the two sites collapse into a single one withK
1
s
=1500±400 nM, similar to the singleK
1
s
=1200±200 nM in the red cell (J.A. Dix, A.S. Verkman & A.K. Solomon,J. Membrane Biol.
89:211–223, 1986). The kinetics of DBDS binding to MCD cells at 0.25 M–1 are characterized by a fast process, =0.14±0.03 sec, similar to =0.12±0.03 sec in the red cell. These similarities show that the physical chemical characteristics of stilbene inhibitor binding to MCD cell band 3 closely resemble those for red cell band 3, which suggests that the molecular structure is highly conserved. 相似文献
19.
Ann E. Wakefield Sarah E. Peters Suneale Banerji Paul D. Bridge Geoffrey S. Hall David L. Hawksworth Lynden A. Guiver rew G. Allen Julian M. Hopkin 《Molecular microbiology》1992,6(14):1903-1911
Pneumocystis carinii causes life-threatening pneumonia in T-lymphocyte-immunodeficient subjects in transplant and oncology units or with acquired immune deficiency syndrome (AIDS). Recent DNA homology studies show P. carinii to be a fungus. To investigate the biology and epidemiology of this parasite further, we elected to determine for it a more precise taxonomic assignment within the fungal kingdom. We screened a wide range of organisms representing the major orders of fungi using DNA amplification and subsequently sequenced a portion of the mitochondrial gene encoding the large subunit ribosomal RNA. Our data show that the opportunistic pulmonary pathogen P. carinii is closely related to the ustomycetous red yeast fungi, a group which includes organisms that are extensively distributed throughout the environment and which release many widely dispersed airborne spores. 相似文献
20.
Julian R. Reid Christopher H. Moore Graeme G. Midwinter Graham G. Pritchard 《Applied microbiology and biotechnology》1991,35(2):222-227
Summary The cell wall-associated proteinase from Lactococcus lactis subsp. cremoris SK11 was partially purified and incubated with
s1-casein for various times up to 48 h. Sixteen trifluoroacetic acid-soluble oligopeptide hydrolysis products were identified by determination of the aminp acid sequence. Eleven of these oligopeptides originated from the 78-residue sequence comprising the C-terminal region of
s1-casein and were present among the products after the first 60 min of digestion. Three oligopeptides from the N-terminal region and two others from the central region of the
s1-casein sequence were also present among the early digestion products although in smaller amounts than most of the oligopeptides from the C-terminal region. No cleat consensus sequence of amino acid residues surrounding the cleavage sites could be identified.Offprint requests to: G. G. Pritchard 相似文献