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31.
Mark A. Batzer Santosh S. Arcot Joshua W. Phinney Michelle Alegria-Hartman David H. Kass Stephen M. Milligan Colin Kimpton Peter Gill Manfred Hochmeister Panayiotis A. Ioannou Rene J. Herrera Donald A. Boudreau W. Douglas Scheer Bronya J. B. Keats Prescott L. Deininger Mark Stoneking 《Journal of molecular evolution》1996,42(1):22-29
The Alu family of intersperesed repeats is comprised of ovr 500,000 members which may be divided into discrete subfamilies based upon mutations held in common between members. Distinct subfamilies of Alu sequences have amplified within the human genome in recent evolutionary history. Several individual Alu family members have amplified so recently in human evolution that they are variable as to presence and absence at specific loci within different human populations. Here, we report on the distribution of six polymorphic Alu insetions in a survey of 563 individuals from 14 human population groups across several continents. Our results indicate that these polymorphic Alu insertions probably have an African origin and that there is a much smaller amount of genetic variation between European populations than that found between other populations groups.
Present address: Department of Pathology, Stanley S. Scott Cancer Center, Louisiana State University Medical Center, 1901 Perdido St., New Orleans, LA 70112
Correspondence to: M.A. Batzer 相似文献
32.
33.
Production of Serine Proteases by the Oyster Pathogen Perkinsus marinus (Apicomplexa) In Vitro 总被引:1,自引:1,他引:0
JEROME F. LA PEYRE DORIS Y. SCHAFHAUSER ESAM H. RIZKALLA MOHAMED FAISAL 《The Journal of eukaryotic microbiology》1995,42(5):544-551
ABSTRACT. Analysis of the cell-free supernatants of Perkinsus marinus cultures by sodium dodecylsulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and silver staining revealed the presence of as many as 17 bands ranging in molecular weight from 239 to 32 kDa. These bands were not present in un-inoculated medium. Moreover, P. marinus produces extracellular proteins that possess proteolytic activities; the cell-free supernatants of P. marinus cultures could digest a variety of proteins including gelatin, casein, fibronectin and laminin. Oyster plasma was also digested by cell-free culture supernatants. The proteolytic activity in cell-free culture supernatants was detected 24 h post-inoculation, while no proteolytic activity could be detected in cell lysates. The proteolytic activities were characterized using substrate-impregnated sodium dodecylsulfate-polyacrylamide gels and had approximate molecular weights ranging from 55 to 35 kDa. The proteolytic activity of cell-free culture supernatants was inhibited by the serine protease inhibitors phenylmethylsulphonyl fluoride, 3,4-dichloroisocoumarin and soybean trypsin inhibitor. In contrast, inhibitors (i.e. trans-epoxysuccinyll-leucylamido(4-guanidino)-butane, 1, 10-phenanthroline, captopril, ethylenediaminetetracetic acid, pepstatin A or diazoacetyl-DL-norleucine methyl ester) from the other three classes of proteases had no effect. It was concluded that the P. marinus proteases in cell-free culture supernatants are serine proteases. 相似文献
34.
Ana M. Celentano Gabriela Gorelik María E. Solana Leonor Sterin-Borda Enri Borda Stella M. Gonzlez Cappa 《Prostaglandins & other lipid mediators》1995,49(3)
PGE2 involvement in experimental Trypanosoma cruzi infection depends on the lethal capacity of the parasite subpopulation used. Mice acutely infected with non-lethal K98 displayed an enhancement in PGE2 serum levels during the acute period, while those infected with lethal T. cruzi subpopulations (RA or K98-2) showed levels not different from normal mice. The enhancement detected in K98 group could be related both to an increased number of CD8+ T cell number and to enhanced PGE2 release per cell by CD8+; values of PGE2 release by adherent cells were not altered in this group. Treatment with cyclooxygenase inhibitors enhanced mortality rates of mice infected with K98, and administration of 16,16-dimethyl PGE2 (dPGE) reversed this effect. However, mice infected with RA did not reduce their mortality rates by administration of diverse doses of dPGE. These findings suggest that PGE2 could play a role in resistance in mice infected with K98. 相似文献
35.
Y. Hailemichael J. W. Smith R. N. Wiedenmann 《Entomologia Experimentalis et Applicata》1994,71(2):155-166
Xanthopimpla stemmator (Thunberg)(Hymenoptera: Ichneumonidae), a solitary endoparasite of pupae of Old World lepidopteran stalkborers, was recently
imported into Texas as a candidate for biological control of New World stalkborers. Information on host acceptability, host
suitability and cues responsible for host finding were necessary to gain an insight into parasite/host interactions, because
of the absence of a coevolutionary history.Xanthopimpla stemmator females were exposed to laboratory-reared one-to six-day-oldDiatraea saccharalis (F.) pupae. An average of 62% of host pupae were accepted and all ages of pupae were equally acceptable. Host suitability
decreased with host age. One- to five-day-old host pupae averaged 31–37% suitability, whereas only 19% of 6-day-old pupae
were suitable. Successful parasitization, defined as the product of the proportion accepted and the proportion suitable, decreased
from 22–23% for 1-, 2- and 3-day-old pupae to 13% for 6-day-old pupae. Sex ratio (female:male) of the parasite progeny increased
with host age. Females comprised 47% of total parasite progeny of 1-day-old and 84% of 6-day-old pupae. The increase in percent
females was a result of a similar number of females in all age classes, coupled with a decrease in the number of males from
older hosts.Xanthopimpla stemmator superparasitized 61% of acceptedD. saccharalis pupae in the laboratory. On dissection, 73% of host pupae with multiple probe wounds were found to contain parasite eggs
or larvae; these hosts contained up to 10 eggs or 7 first-instar larvae. Increased numbers of probes by the parasites were
associated with an increase in successful parasitization. Host seeking activity inX. stemmator was stimulated by the presence of larval frass, host odor and movement of host pupae. Results suggest thatX. stemmator is a good candidate for biological control ofD. saccharalis and possibly other factitious stalkborer hosts. 相似文献
36.
Examination of 111 peacock wrasse [Symphodus tinea (L.)] and 97 brown wrasse ( Labrus merula L.) from the Valencian coast (Spain) yielded 24 metazoan parasite species (11 Digenea, three Cestoda, four Nematoda. one Acanlhocephala, five Crustacea). Eighteen species were from 5. tinea and 17 from L. merula; 11 of the 24 species were common to both hosts. Brillouin's diversity index, was applied to fully censused parasite infracommunities. This is the first time that all the metazoan parasites (internal and external) in any position in the host have been analysed for diversity. High values of prevalence, intensity, and diversity parameters indicate that these labrid fishes support diverse parasite communities. This may be due to their diverse diet, mainly marine invertebrates which are possible intermediate hosts; they also support certain netnatodes and crustaceans which have direct life-cycle. 相似文献
37.
On the origin of Spanish two-rowed barleys 总被引:1,自引:1,他引:0
M. Moralejo I. Romagosa G. Salcedo R. Sánchez-Monge J. L. Molina-Cano 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,87(7):829-836
To investigate the phylogenetic origin of Spanish two-rowed barleys, we studied 44 accessions of old land-races both morphologically and biochemically to ascertain their similarity with 51 entries of old cultivars and land-races of widespread origin across Europe. They were also compared with 20 accessions of Hordeum spontaneum from the Mediterranean basin and other regions of its distribution range, 14 accessions of Moroccan cultivated six-rowed barley land-races, and different six-rowed Spanish and two-and six-rowed European cultivars. CM-(trypsin inhibitors and subunits of the barley tetrameric -amylase inhibitor) proteins and hordeins, all of which are endosperm proteins, were used as biochemical markers. The appearance of separate clusters of the Spanish barleys in the numerical classifications for both protein systems as a result of the existence of characteristic gene combinations that do not exist in entries from other origins permitted us to postulate the existence of local ancestors for most of the Spanish two-rowed barleys studied, and, therefore, a possible in situ domestication. 相似文献
38.
Gerardo Argüello-Astorga Luis Herrera-Estrella Rafael Rivera-Bustamante 《Plant molecular biology》1994,26(2):553-556
Geminiviruses are plant pathogens that replicate by a rolling-circle mechanism, analogous to that used by several prokaryotic ssDNA replicons. Recent reports provide important progress in understanding the structure and functioning of replication origin from these viruses. We have used these data to propose models for the initiation of replication in dicot- and monocot-infecting geminiviruses. 相似文献
39.
M. D. SÁNCHEZ-YÉLAMO 《Botanical journal of the Linnean Society. Linnean Society of London》1994,115(1):9-18
As a result of the surveying of 13 taxa of the genus Diplotaxis, it was found that their leaf flavonoids are flavonol glycosides derived from either kaempferol, quercetin and isorhamnetin. Multivariate analysis of these flavonoid data of taxa suggest a close chemotaxonomic affinity. On the basis of their chemical composition the taxa relationships are discussed. The allopolyploid origin of D. muralis with D. tenuifolia and D. viminea as parentals is strongly supported by chemical evidence. 相似文献
40.
Hans Kuhn 《Biosensors & bioelectronics》1994,9(9-10):707-717
Some goals of bioelectronics—interfacing biology and electronics — are the understanding of supramolecular bioprocesses and the construction of supramolecular devices. The principles for the design and fabrication of machineries with functional components of molecular size are inspired by reflecting on biosystems, and it seems important to consider such principles. We first discuss attempts to construct supramolecular machines, and then we consider the bacterial reaction centre as an example where supramolecular engineering helps to elucidate a bioprocess. We then discuss possible mechanisms leading to the emergence of life-like systems in the light of the basic principles used to design supramolecular devices. Finally, we reflect on prospects in molecular engineering inspired by studying the emergence of life-like systems. 相似文献