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1.
2.
The molecular evolution of mammalian Y-linked DNA sequences is of special
interest because of their unique mode of inheritance: most Y- linked
sequences are clonally inherited from father to son. Here we investigate
the use of Y-linked sequences for phylogenetic inference. We describe a
comparative analysis of a 515-bp region from the male sex- determining
locus, Sry, in 22 murine rodents (subfamily Murinae, family Muridae),
including representatives from nine species of Mus, and from two additional
murine genera--Mastomys and Hylomyscus. Percent sequence divergence was
< 0.01% for comparisons between populations within a species and was
0.19%-8.16% for comparisons between species. Our phylogenetic analysis of
12 murine taxa resulted in a single most- parsimonius tree that is highly
concordant with phylogenies based on mitochondrial DNA and allozymes. A
total evidence tree based on the combined data from Sry, mitochondrial DNA,
and allozymes supports (1) the monophyly of the subgenus Mus, (2) its
division into a Palearctic group (M. musculus, M. domesticus, M.
spicilegus, M. Macedonicus, and M. spretus) and an Oriental group (M.
cookii++, M. cervicolor, and M. caroli), and (3) sister-group relationships
between M. spicilegus and M. macedonicus and between M. cookii and M.
cervicolor. We argue that Y- chromosome DNA sequences represent a valuable
new source of characters for phylogenetic inference.
相似文献
3.
The acrosomic status of spermatozoa prepared for IVF has been evaluated by means of immunofluorescence test from Fenichel and Hsi using calcium A 23187 ionophore as inductor of acrosome reaction (AR). The spontaneous AR remains slight, even after 6 hour-incubation in Menezo B2 (6,8+2,7%). The response to ionophore, moderate before (11,2+9%), frankly increases after a 6h-capacitation (28,9+8,3%) in a group of 25 IVF couples (tubal indication, normal semen, positive fertilization). Nevertheless, it remains slight or null in 4 cases of unexplained repeated failure of fertilization. The response to ionophore A 23187 allows to explore the kinetics of capacitation of spermatozoa and their ability to perform AR. Its significance in terms of fecondance remains to be precised. 相似文献
4.
A number of diverse compounds including divalent metal ions, simple sugars, and common counterions, buffers, and fungicides were surveyed in the laboratory with regard to ability to inhibit germination of field-collected sclerotia from Whetzelinia sclerotiorum. Many compounds were inhibitory and several were comparable in effectiveness to benomyl and other commercial fungicides. Different levels of a given inhibitor were needed to prevent stipe formation, apothecial formation or mycelial germination. Inhibition was not correlated with ionic strength or related to pH. 相似文献
5.
B L Steadman P A Trautman E Q Lawson M J Raymond D A Mood J A Thomson C R Middaugh 《Biochemistry》1989,28(25):9653-9658
Differential scanning calorimetry was performed on the five major lens crystallin fractions [HM-alpha, alpha, beta H, beta L, and (beta s + gamma)] of the bovine lens as well as on more purified forms of alpha- and gamma-crystallins. All were found to be relatively thermally stable although the alpha-crystallin were found to at least partially unfold at an approximately 10 degrees C lower temperature than the beta and gamma fractions. Increasing protein concentration had little effect on gamma-crystallin thermograms but had marked effects on those of the alpha- and beta-crystallins. Increases in the thermal stability with increasing protein concentration for the beta-crystallins can be explained most simply by the known beta L/beta H equilibrium, but, in the case of the alpha-crystallins, excluded volume effects may be an important factor. In both cases, the increased stability at high concentrations could be of physiological relevance. As well as the expected endothermic unfolding transitions, all of the lens crystallins revealed exothermic peaks that correlate with protein precipitation. Interestingly, this phenomenon occurs only after extensive structural alteration in the case of the alpha-crystallins but is present very early in the initial stages of structural perturbation of the beta- and gamma-crystallins. 相似文献
6.
We describe a new species of rail from the Sawmill Sink blue hole on Abaco Island in the northern Bahamas. Known from abundant, beautifully preserved Late Pleistocene fossils, Rallus cyanocavi sp. nov. was a medium-sized, flightless species that probably was endemic to the Little Bahama Bank, which is a carbonate platform surrounded by deeper water. We are uncertain whether R. cyanocavi survived into the Holocene, when higher sea levels transformed the Little Bahama Bank from a single large, Late Pleistocene island (ca. 12000 km2) to the scattering of smaller islands seen today, the largest of which is Abaco (1681 km2). Fossils of additional extinct, flightless species of Rallus probably await discovery on some of the 21 other carbonate banks that span the Bahamian Archipelago. 相似文献
7.
David M. Wilson James Apps Nicholas Bailey Mark J. Bamford Isabel J. Beresford Michael A. Briggs Andrew R. Calver Barry Crook Robert P. Davis Susannah Davis David K. Dean Leanne Harris Tom D. Heightman Terry Panchal Christopher A. Parr Nigel Quashie Jon G.A. Steadman Joanne Schogger Andrew D. Medhurst 《Bioorganic & medicinal chemistry letters》2013,23(24):6897-6901
This Letter describes the discovery of a novel series of H3 receptor antagonists. The initial medicinal chemistry strategy focused on deconstructing and simplifying an early screening hit which rapidly led to the discovery of a novel series of H3 receptor antagonists based on the benzazepine core. Employing an H3 driven pharmacodynamic model, the series was then further optimised through to a lead compound that showed robust in vivo functional activity and possessed overall excellent developability properties. 相似文献
8.
1. Interspecific competition among ants is common, and so is competitive exclusion among dominant ant species. In contrast, specific associations between non‐parasitic ant species are rare, especially in the temperate zones. As an exception, the subordinate ant Camponotus lateralis frequently co‐occurs with the dominant Crematogaster scutellaris but rarely with other dominant ants. 2. This association is one of various associations between Camponotus and Crematogaster species across the world. However, the mechanisms behind these co‐occurences are largely unknown. 3. In the present study, we therefore investigated the association of Ca. lateralis and Cr. scutellaris. We studied the spatial association of the nests, interspecific aggression, both species' cuticular hydrocarbon profiles, and their propensity to follow the other species' pheromone trails. 4. Crematogaster scutellaris usually attacked and displaced the generally submissive Ca. lateralis, but was significantly less aggressive at jointly used trails. Camponotus nests were always in close proximity to Crematogaster nests. 5. The cuticular hydrocarbons of both species consisted of alkanes with chain lengths between C21 and C35. The two species had 25 hydrocarbons in common, including mono‐, di‐, and tetramethyl alkanes. Despite this qualitative similarity, however, the quantitative hydrocarbon composition differed between the two species. 6. Camponotus lateralis followed artificial trails containing trail pheromones of Cr. scutellaris, but the latter did not follow Ca. lateralis trail pheromones. Interspecific trail‐following by Camponotus, but not vice versa, has been observed in another Camponotus–Crematogaster association and may be a more general mechanism that facilitates associations between the two ant genera. 相似文献
9.
Wolfe Steadman D 《American journal of physical anthropology》2001,114(1):61-73
Population genetic and biological distance studies of Late Woodland and Mississippian populations from west-central Illinois have provided insight into a number of prehistoric demographic processes at the regional level. However, a formal analysis of diachronic interregional gene flow has not been attempted within a population genetics framework. In this study, cranial measurements of 489 individuals from 13 skeletal samples across the central and lower Illinois valleys are analyzed to address two central issues. First, the potential impact of Cahokia's decline and associated demographic events on the population structure of west-central Illinois Mississippians is examined. Second, the Mississippian and Late Woodland interregional migration patterns are compared to determine if geographic and/or cultural boundaries affected local population structure. Following Relethford and Blangero ([1990] Hum Biol 62:5-25), R matrix methods are utilized to calculate observed and expected phenotypic variances, minimum genetic distances, and F(ST) values in order to detect patterns of differential external gene flow over time. The results indicate that Late Woodland peoples had a larger sphere of biological interaction than Mississippians. In the Mississippian period, culturally imposed barriers paralleled geographic boundaries between regions such that the geographic distribution of biological variation closely adheres to a classic isolation-by-distance model. Further, intraregional population movement was a more significant contributor to Mississippian population structure than interregional gene flow, even during periods of sociopolitical strife. Small-scale intraregional shuffling is consistent with other recent studies of prehistoric Mississippian biocultural and geographic landscapes in the southeast United States. 相似文献
10.
Simmon KE Steadman DD Durkin S Baldwin A Jeffrey WH Sheridan P Horton R Shields MS 《Journal of microbiological methods》2004,56(2):143-149
An autoclave method for preparing bacterial DNA for PCR template is presented, it eliminates the use of detergents, organic solvents, and mechanical cellular disruption approaches, thereby significantly reducing processing time and costs while increasing reproducibility. Bacteria are lysed by rapid heating and depressurization in an autoclave. The lysate, cleared by microcentrifugation, was either used directly in the PCR reaction, or concentrated by ultrafiltration. This approach was compared with seven established methods of DNA template preparation from four bacterial sources which included boiling Triton X-100 and SDS, bead beating, lysozyme/proteinase K, and CTAB lysis method components. Bacteria examined were Enterococcus and Escherichia coli, a natural marine bacterial community and an Antarctic cyanobacterial-mat. DNAs were tested for their suitability as PCR templates by repetitive element random amplified polymorphic DNA (RAPD) and denaturing gradient gel electrophoresis (DGGE) analysis. The autoclave method produced PCR amplifiable template comparable or superior to the other methods, with greater reproducibility, much shorter processing time, and at a significantly lower cost. 相似文献