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1.
2.
Infertility in human males with autosomal translocations: meiotic study of a 14;22 Robertsonian translocation 总被引:10,自引:2,他引:8
M. R. Guichaoua B. Quack R. M. Speed B. Noel A. C. Chandley J. M. Luciani 《Human genetics》1990,86(2):162-166
Summary Pachytene analysis was undertaken in a male patient heterozygous for a 14q22q Robertsonian translocation. The relatively low rate of XY autosome association led us to examine the relationships existing between the chromosomes involved in the translocation, the rate of XY-autosome association and the degree of spermatogenic failure. Cytogenetic investigations in infertile men and the results of the meiotic studies suggest a direct correlation between the frequency of XY-autosome association at pachytene and the degree of spermatogenic failure. Whether associations arise as a consequence or cause of germ cell failure is still not certain. 相似文献
3.
4.
Hardies SC; Martin SL; Voliva CF; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1986,3(2):109-125
5.
6.
Summary A comparative study of the association of mitotic acrocentric chromosomes and acrocentric bivalents at the pachytene stage shows that at least two factors can act in the associative behaviour of these chromosomes: (1) Nor activity and (2) the presence of satellite DNA in the short arms of these chromosomes. These factors do not act with the same intensity in the two cell lines studied. In lymphocytes, Nor activity prevails, whereas satellite DNA plays the main role in the association of acrocentric chromosomes in germ cells at the pachytene stage. 相似文献
7.
Meiotic investigation is rare in male infertility. Now, some mutations affecting spermatogenesis exhibit characteristic cytogenetic figures, whereas testicular histology does not show specific aspects of this pathology. In male infertility with abnormal somatic caryotype, the aim of meiotic survey is to find the mechanisms inducing spermatogenic failure, and thus to lead to a better understanding of normal spermatogenesis. In addition to cytogenetic techniques, meiosis is also investigated by electron microscopy and molecular biology. Also, we think that a larger place must be grant to meiotic study in male infertility evaluation when the indication of testicular histopathology was settled. 相似文献
8.
A major difference between the divergence patterns within the lines-1 families in mice and voles 总被引:3,自引:0,他引:3
Vanlerberghe F; Bonhomme F; Hutchison CA d; Edgell MH 《Molecular biology and evolution》1993,10(4):719-731
L1 retroposons are represented in mice by subfamilies of interspersed
sequences of varied abundance. Previous analyses have indicated that
subfamilies are generated by duplicative transposition of a small number of
members of the L1 family, the progeny of which then become a major
component of the murine L1 population, and are not due to any active
processes generating homology within preexisting groups of elements in a
particular species. In mice, more than a third of the L1 elements belong to
a clade that became active approximately 5 Mya and whose elements are >
or = 95% identical. We have collected sequence information from 13 L1
elements isolated from two species of voles (Rodentia: Microtinae: Microtus
and Arvicola) and have found that divergence within the vole L1 population
is quite different from that in mice, in that there is no abundant
subfamily of homologous elements. Individual L1 elements from voles are
very divergent from one another and belong to a clade that began a period
of elevated duplicative transposition approximately 13 Mya. Sequence
analyses of portions of these divergent L1 elements (approximately 250 bp
each) gave no evidence for concerted evolution having acted on the vole L1
elements since the split of the two vole lineages approximately 3.5 Mya;
that is, the observed interspecific divergence (6.7%-24.7%) is not larger
than the intraspecific divergence (7.9%-27.2%), and phylogenetic analyses
showed no clustering into Arvicola and Microtus clades.
相似文献
9.
Molecular phylogeny and divergence times of drosophilid species 总被引:32,自引:15,他引:17
The phylogenetic relationships and divergence times of 39 drosophilid
species were studied by using the coding region of the Adh gene. Four
genera--Scaptodrosophila, Zaprionus, Drosophila, and Scaptomyza (from
Hawaii)--and three Drosophila subgenera--Drosophila, Engiscaptomyza, and
Sophophora--were included. After conducting statistical analyses of the
nucleotide sequences of the Adh, Adhr (Adh-related gene), and nuclear rRNA
genes and a 905-bp segment of mitochondrial DNA, we used Scaptodrosophila
as the outgroup. The phylogenetic tree obtained showed that the first major
division of drosophilid species occurs between subgenus Sophophora (genus
Drosophila) and the group including subgenera Drosophila and Engiscaptomyza
plus the genera Zaprionus and Scaptomyza. Subgenus Sophophora is then
divided into D. willistoni and the clade of D. obscura and D. melanogaster
species groups. In the other major drosophilid group, Zaprionus first
separates from the other species, and then D. immigrans leaves the
remaining group of species. This remaining group then splits into the D.
repleta group and the Hawaiian drosophilid cluster (Hawaiian Drosophila,
Engiscaptomyza, and Scaptomyza). Engiscaptomyza and Scaptomyza are tightly
clustered. Each of the D. repleta, D. obscura, and D. melanogaster groups
is monophyletic. The splitting of subgenera Drosophila and Sophophora
apparently occurred about 40 Mya, whereas the D. repleta group and the
Hawaiian drosophilid cluster separated about 32 Mya. By contrast, the
splitting of Engiscaptomyza and Scaptomyza occurred only about 11 Mya,
suggesting that Scaptomyza experienced a rapid morphological evolution. The
D. obscura and D. melanogaster groups apparently diverged about 25 Mya.
Many of the D. repleta group species studied here have two functional Adh
genes (Adh-1 and Adh-2), and these duplicated genes can be explained by two
duplication events.
相似文献
10.
Root, underground and above-ground biomass were measured on various wheat cultivars from 1986 to 1988 in the south-east of France. The results are expressed as root: total (f
r) or underground: total (f
u) biomass fractions. Observed f
r and f
u values are in good agreement with previous results. f
r and f
u decrease steadily from emergence to maturity, with an exponential tendency. When using cumulative growth degree days since emergence relative to cumulative growth degree days until ear emergence () as time scale, f
r and f
u can be expressed as simple functions of % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGceaqabeaacaWGMb% addaWgaaqaaiaadkhaaeqaamaabmaabaGccqaH4oqCdaahaaWcbeqa% aiaacQcaaaaamiaawIcacaGLPaaakiabg2da9iaaicdacaGGUaGaaG% imaiaaiwdacqGHRaWkcaaIWaGaaiOlaiaaiwdacaaI4aGaamyzamaa% CaaaleqabaGaeyOeI0IaaGymaiaac6cacaaI0aGaaGioaiabeI7aXn% aaCaaameqabaGaaiOkaaaaaaaakeaacaWGMbaddaWgaaqaaiaadwha% aeqaamaabmaabaGccqaH4oqCdaahaaWcbeqaaiaacQcaaaaamiaawI% cacaGLPaaakiabg2da9iaaicdacaGGUaGaaGymaiaaikdacqGHRaWk% caaIWaGaaiOlaiaaiIdacaaI4aGaamyzamaaCaaaleqabaGaeyOeI0% IaaGOmaiaac6cacaaIYaGaaGioaiabeI7aXnaaCaaameqabaGaaiOk% aaaaaaaaaaa!610D!\[\begin{gathered} f_r \left( {\theta ^* } \right) = 0.05 + 0.58e^{ - 1.48\theta ^* } \hfill \\ f_u \left( {\theta ^* } \right) = 0.12 + 0.88e^{ - 2.28\theta ^* } \hfill \\ \end{gathered} \]The incremental root biomass partitioning coefficient, % MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySde2aaS% baaSqaaiaadkhaaeqaaOGaeyypa0JaaiikaiaadsgacaWGxbWaaSba% aSqaaiaadkhaaeqaaOGaai4laiaadsgacaWG0bGaaiykaiaac+caca% GGOaGaamizaiaadEfadaWgaaWcbaGaamiDaaqabaGccaGGVaGaamiz% aiaadshacaGGPaaaaa!4834!\[\alpha _r = (dW_r /dt)/(dW_t /dt)\], which describes the net increase in root biomass dW
r over time dt relative to the increase in total biomass (dW
r) over the same time period, has been derived from f and the relative growth rate. Its time course is accurately represented by% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9sqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGaeqySdegdda% WgaaqaaiaadkhaaeqaamaabmaabaGccqaH4oqCdaahaaWcbeqaaiaa% cQcaaaaamiaawIcacaGLPaaakiabg2da9iabgkHiTiaaicdacaGGUa% GaaGymaiaaiwdacqGHRaWkcaaIWaGaaiOlaiaaiAdacaaIZaGaamyz% amaaCaaaleqabaGaeyOeI0IaaGimaiaac6cacaaI5aGaaGioaiabeI% 7aXnaaCaaameqabaGaaiOkaaaaaaaaaa!4D15!\[\alpha _r \left( {\theta ^* } \right) = - 0.15 + 0.63e^{ - 0.98\theta ^* } \]Under our experimental conditions, with no severe water stresses or nutrient deficiencies, and for our sampling frequency, around 2 weeks, the development scale , is the main factor governing the time courses of f
r, f
u and r. 相似文献