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81.
Rebuzzini P Neri T Mazzini G Zuccotti M Redi CA Garagna S 《Cytogenetic and genome research》2008,121(1):18-24
It is common knowledge that mouse embryonic stem cell (mESC) lines accumulate chromosomal changes during culture. Despite the wide use of mESCs as a model of early mammalian development and cell differentiation, there is a lack of systematic studies aimed at characterizing their karyological changes during culture. We cultured an mESC line, derived in our laboratory, for a period of 3 months investigating its chromosome complement at different times. About 60% of the metaphases analysed were euploid throughout the culture period but, from passage 13, only 50% of the euploid metaphases had a proper chromosome complement. The remaining 50% showed chromosome abnormalities, mainly gain or loss of entire chromosomes, both within the same passage and among different passages analysed. The very heterogeneous spectrum of abnormalities indicates a high frequency of chromosome mutations that arise continuously during culture. The heterogeneity of the aberrant chromosome constitution of 2n = 40 metaphases, observed at different passages of culture, might be due either to their elimination or to a shift towards the hypoeu- or hypereuploid population of those metaphases that accumulate further chromosome abnormalities. The stability of the frequency of eu-, hypoeu- and hypereuploid populations during culture might, however, be due to the elimination of those cells that carry a high mutational burden. Based on our results, we suggest that karyotype analysis of the euploid cell population of mESC lines is necessary when such lines are used in the production of chimeric mice, for their contribution to the germ line, or when they are differentiated into specific cell types. 相似文献
82.
83.
Field and herbarium studies on wild flowering plants of Ethiopia furnished 203 species consumed by the community. These account
for about 3% of the higher plant species in the country and comprise herbs (37%), shrubs (32%), and trees (31%). Species with
edible fruits contributed to 61.6%, leaves 27.7%, stems 14.4%, roots 13.3%, and seeds 10.3%. About 15% are considered famine
foods. Forest habitats gave 102 species, woodlands 99, grasslands 83, bushlands 52, rocky and dry areas 47, cultivated places
41, riverbanks 31, and roadsides/ disturbed areas 25. The altitudinal distribution gave 148 species between 1500-2400 m, 144
below 1500 m and 81 above 2400 m a.s.l. Some species are wild and others slightly or strongly associated with humans, revealing
a living analogue of the wild-semiwild-domesticated continuum. Full-scale ethnobotanical studies, implementing appropriate
conservation measures and domesticating and integrating promising taxa into existing crops are favored for the purpose of
diversification of food sources, ensuring food security, and maintenance of biodiversity and environmental integrity. 相似文献
84.
Single-cell quantitative RT-PCR analysis of Cpt1b and Cpt2 gene expression in mouse antral oocytes and in preimplantation embryos 总被引:1,自引:0,他引:1
Gentile L Monti M Sebastiano V Merico V Nicolai R Calvani M Garagna S Redi CA Zuccotti M 《Cytogenetic and genome research》2004,106(2-4):215-221
Among crustacean Decapoda numerical chromosome variability is frequent, and it has been hypothesized that the presence of supernumerary chromosomes accounts for this variability. Thanks to the improvement of cytogenetic analysis by chromosomal banding techniques, supernumerary B chromosomes (Bs) have been demonstrated in Nephrops norvegicus, Homarus americanus,Palinurus elephas and P. mauritanicus, belonging to different crustacean families. In all four species Bs were variable in number, mainly heterochromatic and undigested by various endonucleases, and in meiosis they showed non-Mendelian segregation. Compared to the other chromosomes of the complement, the Bs are very small in almost all species, but some of them were very large in N. norvegicus. 相似文献
85.
The other chromatin 总被引:5,自引:0,他引:5
Current understanding of heterochromatin, thanks to molecular data, focuses on its performing several functions in evolution and development. Heterochromatin shows characteristic distribution patterns in karyotypes and contributes to the broad scattering of genome sizes through biological taxa. Heterochromatin remains compacted and thus different from properly stained euchromatin during somatic interphase. A minimum amount of heterochromatin, however, is required for it to be visible in light microscopy. It may further escape notice during the dynamic processes of embryogenesis and gametogenesis. Present-day biology is in search of specific proteins and DNA sequences that comprise heterochromatin. The data that result from overcoming the threshold of visibility will support understanding of interference by heterochromatin in ontogeny and evolution. The contributions of Sigrid and Wolfgang Beermann to the study of heterochromation diminution (DNA elimination) are recalled, and we also discuss the functions and effects of heterochromatin on differential DNA endoreplication and in speciation. 相似文献
86.
Manuela Monti CarloAlberto Redi Ernesto Capanna 《European journal of histochemistry : EJH》2022,66(2)
In this paper, we report genome size (GS) values for nine cockroaches (order Blattodea, families Blattidae, Blaberidae and Ectobiidae, ex Blattelidae), three of which are original additions to the ten already present in the GS database: the death’s head roach (Blaberus craniifer), the Surinam cockroach (Pycnoscelus surinamensis) and the Madeira cockroach (Leucophaea maderae). Regarding the American cockroach (Periplaneta americana), the GS database contains two contrasting values (2.72 vs 3.41 pg); likely, the 2.72 pg value is the correct one as it is strikingly similar to our sperm DNA content evaluation (2.80 ± 0.11 pg). Also, we suggest halving the published GS of the Argentine cockroach Blaptica dubia and the spotted cockroach (the gray cockroach) Nauphoeta cinerea discussing i) the occurrence of a correlation between increasing 2n chromosome number and GS within the order Blattodea; and ii) the possible occurrence of a polyploidization phenomenon doubling a basic GS of 0.58 pg of some termite families (superfamily Blattoidea, epifamily Termitoidae).Key words: genome size, C-DNA content, cockroaches, Blattodea 相似文献
87.
M C Cerda S Berríos R Fernández-Donoso S Garagna C Redi 《Biology of the cell / under the auspices of the European Cell Biology Organization》1999,91(1):55-65
The number and associations of heterochromatin chromocenters, nucleoli, centromeres and telomeres were studied in the nucleus of different somatic cells of Mus domesticus. Fibroblasts of the cell line 3T3, kidney cells (primary culture), and bone marrow cells were used. The above mentioned nuclear and chromosome markers were identified by DAPI/actinomycin D, indirect immunofluorescence with anti-centromere antibodies, silver impregnation for nucleolar proteins and fluorescence in situ hybridisation (FISH) with telomeric probes. The quantitative analysis of the nuclei showed that the pericentromeric heterochromatin is organised in about 18 chromocenters per nucleus in the 3T3 cells, and about seven in kidney and bone marrow cells, having generally a peripheral distribution in the nucleus of all the studied cells. Several aggregated centromeres were participating in each of the chromocenters, about four centromeres per 3T3 cell and about six centromeres per kidney and bone marrow cells. Some of the chromocenters were also in close association with nucleoli. The number of telomeric labels per nucleus was as expected for each chromosome set (2n = 68-70 and 2n = 40). About half of the telomeric signals were loosely aggregated within the heterochromatic blocks while the rest were distributed in the nucleus as unrelated units not bound with chromocenters. The three cell types have complex nuclear territories formed by different chromosomal domains: the pericentromeric heterochromatin, centromeres, proximal telomeres and nucleoli. With the exception of some bone marrow cells, we have not found a nuclear polarisation of the analysed chromosomal markers compatible with the Rabl configuration. However, Rabl anaphasic polarisation allows the contact of centromeric regions making possible that centromeric associations arise. If in addition, associative elements such as constitutive heterochromatin or nucleoli are close to the centromeric regions, like in Mus domesticus chromosomes, then the associations might be consolidated and persist until the interphase. These associations may be the origin of the nuclear domains described here for Mus domesticus somatic cells. 相似文献
88.
The genetic relationships of Rhizobium isolated from temperate and tropical perennial Trifolium species were investigated
using PCR-based nucleotide sequence analysis of 16S and 23S rDNA regions. Comparative analysis of partial 23S rDNA sequences
clustered Rhizobium isolates effective with T. semipilosum, T. repens, T. pratense, T. hybridum and T. fragiferum into two
distinct groups. These groups were consistent with the pattern of symbiotic effectiveness observed in cross-inoculation experiments.
Our data suggested that strains from T. semipilosum were more closely related phylogenetically to R. etli, indicating that
these strains do not belong in the R. leguminosarum bv trifolii group. Further differentiation of Rhizobium strains effective
on T. semipilosum was reflected in the broader metabolic profile observed using the BIOLOG MicroPlate TM system to evaluate carbon utilization.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
89.
Mesfin Wondafrash Bernard Slippers Jeff Garnas Géraldine Roux Jiri Foit David W. Langor Brett P. Hurley 《Biological invasions》2016,18(8):2283-2297
During the first half of the twentieth century, two accidental cases of introduction of Pissodes weevils were recorded from the southern hemisphere. The weevils in South Africa were identified as the deodar weevil (Pissodes nemorensis) and those in South America as the small banded pine weevil (Pissodes castaneus). Wide distribution of the two species in their invasive range, general difficulty in identifying some Pissodes spp., and the varying feeding and breeding behaviours of the species in South Africa has necessitated better evidence of species identity and genetic diversity of both species and population structure of the species in South Africa. Barcoding and the Jerry-to-Pat region of the COI gene were investigated. Morphometric data of the South African species was analysed. Our results confirmed the introduction of only one Pissodes species of North American origin to South Africa. However, this species is not P. nemorensis, but an unrecognized species of the P. strobi complex or a hybrid between P. strobi and P. nemorensis. Only P. castaneus, of European origin, was identified from South America. We identified ten mitochondrial DNA haplotypes from South Africa with evidence of moderate genetic structure among geographic populations. Terminal leader and bole-feeding weevils did not differ at the COI locus. A single haplotype was identified from populations of P. castaneus in South America. Results of the present study will have implications on quarantine, research and management of these insect species. 相似文献
90.