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161.
Molecular evolution of the period gene in Drosophila athabasca 总被引:1,自引:0,他引:1
We measured nucleotide variability within and between the three semispecies
of the Drosophila athabasca complex, at the period (per) gene by using a
polymerase chain reaction-based four-cutter restriction- enzyme analysis.
The levels of polymorphism varied considerably between the three
semispecies. Our results for per, combined with previous data for X-linked
allozymes, suggest that the X chromosome in the western- northern
semispecies is less variable than expected under an equilibrium-neutral
model. Both the pattern of divergence between the semispecies and a
cladistic clustering of per haplotypes support the previously hypothesized
grouping of eastern A and eastern B as the two most recently diverged
semispecies. A 21-bp in-frame segment in the region of per which shares
sequence similarity with the neuronal development gene single minded is
deleted in all eastern A and eastern B flies examined but is present in all
of the western-northern flies and all other published per sequences.
Despite these hints that there may be significant differences at the per
gene between the semispecies, especially the western-northern group versus
the two eastern groups, there is no compelling evidence that per is
involved in the mating song differences between the semispecies.
相似文献
162.
163.
Regional, vertical and seasonal distribution of phytoplankton and photosynthetic pigments in Lake Baikal 总被引:5,自引:0,他引:5
Fietz Susanne; Kobanova Galina; Izmest'eva Lyubov; Nicklisch Andreas 《Journal of plankton research》2005,27(8):793-810
A 3-year phytoplankton study was carried out in Lake Baikal(Siberia) as part of the CONTINENT project and in conjunctionwith a 60-year long monitoring programme by the Irkutsk StateUniversity. A combination of microscopy and high performanceliquid chromatography (HPLC) pigment analysis was used. Allover the lake, the dominant functional group (by biovolume)was the vernal diatom blooms, due to the dominance of endemicCyclotella species. Chlorophyll a (Chl a) was significantlyhighest at the Selenga and Barguzin inflows (2.39 ± 0.34and 2.49 ± 0.18 nmol L1, mean ± 95% CI,respectively) and higher in the South than in the North (1.43± 0.26 and 0.96 ± 0.13 nmol L1). This variationof Chl a reflected changes in the phytoplankton composition.Diatoms and Chrysophyceae were the major contributors to thetotal Chl a except in the South (Chlorophyceae) and SelengaDelta (cyanobacterial picoplankton). There were also indicationsof species composition changes due to enhanced P-loading fromthe Selenga River. However, canonical analyses indicated thattemperature and stratification were the major driving forcesfor regional distribution patterns and seasonal succession.It seems likely that further global warming will cause a shiftin the species and group composition towards small cells atthe expense of the large endemic diatom flora. 相似文献
164.
165.
Karl H. Engesser W. Fietz P. Fischer P. Schulte Hans-J. Knackmuss 《FEMS microbiology letters》1990,69(3):317-321
A bacterial strain, Pseudomonas sp. POB 310, was enriched with 4-carboxy biphenyl ether as sole source of carbon and energy. Resting cells of POB 310 co-oxidize a substrate analogue, 4-carboxybenzophenone, yielding 1,2-dihydro-1,2-dihydroxy-4-carboxy-benzophenone. The ether bond of 3- and 4-carboxy biphenyl ether is cleaved analogously by initial 1,2-dioxygenation, yielding a hemiacetal which is hydrolysed to protocatechuate and phenol. These intermediates are degraded via an ortho and meta pathway, respectively. Alternative 2,3- and 3,4-dioxygenation can be ruled out as triggering steps in carboxy biphenyl ether degradation. 相似文献
166.
Biodiversity and Conservation - In recent years, biodiversity has declined faster than ever before in human history. Appropriate monitoring methods are needed to detect the decline of populations... 相似文献
167.
Joanna Fietz Jürgen Tomiuk Franz-Rainer Matuschka Dania Richter 《Applied and environmental microbiology》2014,80(12):3615-3621
In Europe, dormice serve as competent reservoir hosts for particular genospecies of the tick-borne agent of Lyme disease (LD) and seem to support them more efficiently than do mice or voles. The longevity of edible dormice (Glis glis) and their attractiveness for ticks may result in a predominance of LD spirochetes in ticks questing in dormouse habitats. To investigate the role of edible dormice in the transmission cycle of LD spirochetes, we sampled skin tissue from the ear pinnae of dormice inhabiting five different study sites in south western Germany. Of 501 edible dormice, 12.6% harbored DNA of LD spirochetes. Edible dormice were infected most frequently with the pathogenic LD spirochete Borrelia afzelii. The DNA of B. garinii and B. bavariensis was detected in ca. 0.5% of the examined individuals. No spirochetal DNA was detectable in the skin of edible dormice until July, 6 weeks after they generally start to emerge from their obligate hibernation. Thereafter, the prevalence of spirochetal DNA in edible dormice increased during the remaining period of their 4 to 5 months of activity, reaching nearly 40% in September. Males were more than four times more likely to harbor LD spirochetes than females, and yearlings were almost twice more likely to be infected than adults. The seasonality of the prevalence of LD spirochetes in edible dormice was pronounced and may affect their role as a reservoir host in respect to other hosts. 相似文献
168.
169.
Glandular excision in total glandular mastectomy and modified radical mastectomy: a comparison 总被引:5,自引:0,他引:5
F E Barton J M English W B Kingsley M Fietz 《Plastic and reconstructive surgery》1991,88(3):389-92; discussion 393-4
Total glandular mastectomy and modified radical mastectomy were compared for the amount of breast tissue remaining after surgery. Multiple biopsies were taken from the anterior chest walls of women following total glandular mastectomy (N = 27) and modified radical mastectomy (N = 28) to try to detect any residual glandular tissue. Regardless of procedure performed, breast tissue was identified histologically in 5 percent of all biopsy specimens (159 and 161, respectively). One of every five operative fields was shown to have glandular elements in at least one of the biopsy sites; the positive biopsies did not form a discernible pattern. The residual breast tissue in each of these patients averaged less than 1 gm. On the basis of this study, modified radical mastectomy and total glandular mastectomy appear to be equally effective in removing most of the breast. 相似文献
170.
Cyclins are indispensable elements of the cell cycle and derangement of their function can lead to cancer formation. Recent studies have also revealed more mechanisms through which cyclins can express their oncogenic potential. This review focuses on the aberrant expression of G1/S cyclins and especially cyclin D and cyclin E; the pathways through which they lead to tumour formation and their involvement in different types of cancer. These elements indicate the mechanisms that could act as targets for cancer therapy. 相似文献