Multiple forms of male-specific simple repetitive sequences in the genusMus

Summary Previous reports indicate that in laboratory strains of mice, males are distinct from females in possession of repetitive DNA, notably devoid of Eco RI and Hae III sites and rich in the simple tetranucleotides GATA/GACA. We report here that such sequences originated in an ancestor common to laboratory mice,Mus hortulanus, M. spretus, and possibly alsoM. cookii. Interestingly, other male-specific satellite sequences were detected inM. caroli, M. cookii, M. saxicola, andM. minutoides. This novel satellite is also likely to be composed of simple repetitious sequences, but does not contain GATA and GACA. Thus, the Y chromosome appears to contain a disproportionately large amount of simple repetitious DNA. An attractive explanation for these results is that long tandem arrays of simple repeated sequences are generated at high frequency throughout the genome and that they are retained for a longer time on the Y chromosome due to the absence of homologous pairing at meiosis.     

Experimental evidence on the affinities ofPapaver somniferum (Papaveraceae)

Results obtained from crossing experiments betweenP. somniferum subsp.somniferum (2n = 22) and subsp.setigerum (2n = 44),P. glaucum (2n = 14) andP. gracile (2n = 14) and from the observation of meiotic chromosome pairing in the various hybrids obtained do not provide straightforward evidence for the hypothesis thatP. somniferum originated as a triploid hybrid between taxa similar toP. glaucum andP. gracile (Kadereit 1986a, b).—On the one hand, the pattern of crossability found reflects the closer similarity of subsp.somniferum toP. glaucum and of subsp.setigerum toP. gracile, which was interpreted as segregation of parental characters, and the high frequency of 2n = 28 chromosomes among F₂-progeny from the hybrid subsp.somniferum × subsp.setigerum (2n = 33) might reveal n = 7 as the base number also ofP. somniferum. On the other hand, however, the general difficulty of obtaining hybrids, and the low incidence of bivalent formation in their meiosis, probably indicating a lack of chromosome homology between the different species, do not fit the above hypothesis.—These results are in marked contrast to the morphological similarity between the three species involved.     

Molecular biology of Philadelphia chromosome in chronic granulocytic leukaemia and acute lymphoblastic leukaemia

In classical t(9;22) translocation, as observed in chronic granulocytic leukemia (CGL), a hybrid DNA unit is produced, including a rearranged PHL gene, previously known as bcr (breakpoint cluster region) plus the translocated c-abl gene from chromosome 9: a hybrid bcr-abl protein, p210 is formed, with increased tyrosine kinase activity. Such DNA rearrangement, with a p210 protein synthesis, is also found in cases of Philadelphia-positive acute lymphoblastic leukemia (ALL), but in apparently similar cases the bcr gene is not rearranged, and a novel p190 abl-related protein can be found; c-abl rearrangement has also been observed.It is thus established that correlations between cytogenetic and molecular events can be found in CGL and ALL, as in other haemopoietic malignancies: translocation and possible rearrangement of the c-abl oncogene seem of particular importance in this case.     

Complete maps of IS1, IS2, IS3, IS4, IS5, IS30 and IS150 locations in Escherichia coli K12

Summary In this paper complete distribution maps are presented of the seven IS elements 1, 2, 3, 4, 5, 30 and 150. These maps were obtained during the construction of an almost complete restriction map of the Escherichia coli genome of K12 strain BHB2600. The positions of IS elements were correlated to this map. The distribution of integration sites of all IS types is nonrandom. Besides a large gap from 79 min to 96 min, there is a pronounced IS cluster at 6 min and another at 97 min, map locations that have low gene incidences on the classical map. One cluster coincides with a region of IS induced rearrangements. The IS distribution pattern was compared to patterns of strains W3110 and HB101.     

Delimitation ofPelargonium sect.Glaucophyllum (Geraniaceae)

Pelargonium otaviense Knuth andP. spinosum Willd. are excluded from sect.Glaucophyllum, whileP. grandiflorum (Andr.)Willd.,P. patulum Jacq. andP. tabulare (Burm. f.)L'Hérit. of sect.Eumorpha are included. Sect.Glaucophyllum is characterized by green to glaucous vegetative organs and zygomorphic white to pink corolla with five narrow petals. All the species have an identical pollen and chromosome morphology, the same basic chromosome number (x = 11) and similar flavonoid patterns. A close relationship between sect.Glaucophyllum and sect.Pelargonium is indicated by the occurrence of natural hybrids and concordant characters. Isorhamnetin and luteolin have been detected in the genus for the first time.     

Breeding Systems in American and Asian Trillium Species by Means of Chromosome Analyses

Abstract Species of Trillium have a disjunct distribution occurring in both North America and eastern Asia. In North America all 36 species are diploid. The 11 species of eastern Asia, however, include only a single diploid with all the other species being polyploids. Why do different patterns of speciation develop in North America and in eastern Asia? The breeding systems of populations in the North American T. erectum, T. grandiflorum and T. ovatum , and in Asian T. kamtschaticum were investigated by estimating the inbreeding coefficient from cold-induced banding patterns which reveal homozygotes and heterozygotes. From the analyses of the inbreeding coefficients, T. erectum, T. grandiflorum and the Pacific coastal species, T. ovatum are predominantly inbreeding species. T. ovatum populations from the Rocky Mountain region are outbreeders. However the Japanese species, T. kamtschaticum has a mixture of outbreeding and inbreeding among populations. The development of polyploid systems in Asia is possibly the result of the diversity of the breeding systems among the populations. The shift from outbreeding to inbreeding appears to be an important key step in the occurrence of poliploids by hybridization between the different species.     

Occurrence of rye (Secale cereale) 350-family DNA sequences inAgropyron and otherTriticeae

Evidence is presented that in the R and P genomes (Secale cereale andAgropyron cristatum, respectively) of theTriticeae there exist closely related 350-family DNA sequences in the terminal heterochromatin. This observation is compared to the relationships between these two genomes derived from a comparison of theNor and5 S DNA loci as well as the available data on morphological characters, chromosome pairing, and isozyme studies. It is concluded that the R and P genomes are not closely related and that the common presence of very similar 350-family DNA sequences reflects the parallel amplification of this family of DNA sequences.     

The cytogeographical distribution pattern ofAllium (Alliaceae) in the Greek Peninsula and Islands

Greece is considered as a secondary centre of evolution for the genusAllium since it possesses about 50% of the species known from the whole Flora Europaea area. In the present investigation 44 GreekAllium spp. have been studied and new chromosome counts are reported from 40 populations and 17 species. The distribution of the different cytotypes (x = 7, x = 8, x = 11 and 2n = 2x, 3x, 4x, 5x, 6x, 7x) in Greece is discussed. From the four phytogeographical subdivisions recognized, South continental Greece shows the greatest species and karyotype diversity. This phenomenon is probably due to the geographical position and to the geological history of this area which has received species and populations from different directions. Subsequently, hybridization apparently has been of evolutionary importance.The genusAllium in Greece I.     

Decreased fertility in related females heterozygous for the 1/29 chromosome translocation

Eighteen heifers and 120 cows which were descendants of a presumed 1/29 carrier Simmental bull were karotyped. Nine heifers (50%) and 48 cows (40%) were found to be heterozygous for the 1/29 translocation (59, XX, t(1q;29q)). The other animals were chromosomally normal (i.e., 60, XX) or not karotyped. The 48 1/29 cows were compared with 72 chromosomally normal cows with regards to days to first conception, calving interval, percentage of calves conceived, percentage of calves weaned and production efficiency (% calved conceived × % calved weaned). Nine carrier heifers were compared to the nine noncarrier heifers as to pregnancy status. Carrier, noncarrier and nonkarotyped relatives were compared to each other and to contemporary females with regard to pregnancy status at their initial exposure to males. The percentage of calves conceived (calving efficiency) in the 72 noncarrier and the 48 females heterozygous for the 1/29 translocation were 81.5 and 74.8%, respectively (P<0.07). Although days to first conception was longer and percentage of calves weaned and production efficiency were lower in the female heterozygous for the 1/29 translocation, the differences were not statistically different (P>0.10) from the noncarriers. Pregnancy rate was 44.4 and 66.7% (P>0.10) for nine carrier and nine noncarrier heifers, respectively. The pregnancy rate of carrier (65.4%), noncarrier (73.2%) and nonkarotyped (77.8%) relatives of this sire at their mating as yearlings, did not differ (P>0.10). The pregnancy rate as yearlings of carrier females (65.4%) and contemporary heifers (79.8%) did differ (P<0.05). Comparing the pregnancy rate as yearlings of all descendants (72.0%) of the Simmental sire to contemporary heifers (79.8%), a significant decrease (P<0.05) was found indicating that fertility of this sire may have been lower than other sires or that other factors beside the translocation affected fertility.     

五种恙螨染色体核型的研究

恙螨染色体的研究迄今仅Shirai等(1984)简要地报道了三种纤恙螨的染色体核型。本实验采用压片法和改良空气干燥法,研究观察五种恙螨有丝分裂染色体核型。初静止化蛹1—3天的成蛹阶段是制作恙螨有丝分裂染色体标本的最佳虫期。微红纤恙螨,地里纤恙螨和巨螫齿恙螨染色体数目为2n=14;苍白纤恙螨和小板纤恙螨为2n=16。染色体呈大小不等的小棒状,单着丝粒,但多不清晰,仅可见着丝点区浅染。部分核型出现染色体异型现象。核型性别未明,性别决定机制不清。