Cytogenetic studies of cultivatedCrocus sativus (Iridaceae)

Meiosis and mitosis are described in cultivatedCrocus sativus of Iran. This indicates that this species is an autotriploid and sterile. Karyotype analysis, rare inversions, laggard chromosomes and distribution of chromosomes in the first anaphase are described, and the reasons for its sterility are given.     

Scanning and transmission electron microscopy of human ejaculate spermatozoa with special reference to their abnormal forms

Summary Spermatozoa from fertile and infertile human ejaculates were observed under the scanning electron microscope. A parallel study of sections was performed by transmission electron microscope.The normal head shows under the scanning electron microscope vesicular elevations in the region of the acrosome and a smooth and rigid appearance corresponding to the postnuclear cap whose occurrence is confirmed under the transmission electron microscope. Immediately anterior to this cap a shallow furrow transverses the head. Duplicated, unusually large or small and deformed heads are found under the scanning electron microscope. Most of these abnormal heads show no surface structure suggesting an acrosome.The neck and middle piece are occasionally, though frequently in abnormal spermatozoa, covered by a cytoplasmic droplet. Otherwise, the mitochondrial sheath is recognized under the scanning electron microscope as a beaded thickening in the middle piece. The lack of mitochondria is manifested by a smooth middle piece thinner than the principal portion. Transmission electron microscopy of sections reveals various types of anomalies in the number of cores, core filaments and mitochondria embedded in the cytoplasmic droplets.Abnormalities in the principal portion of the tail such as duplication, unusual thickness and length are shown under the scanning electron microscope.The investigation indicates that scanning electron microscopy is suited for the clinical as well as cytological examination of human ejaculate spermatozoa.     

小伞山羊草(Aegilops umbellata)恢复基因向小麦的转移

鉴定了小伞山羊草(Ae.umbellulata)6条染色体的中国春添加系对T型细胞质雄性不育系育性的影响,发现UAD能较好地恢复T型不育系的育性,表明染色体A上携带有育性恢复基因。添加染色体A在提莫菲维细胞质背景中通过雄配子的传递率为15.6%。同时进一步证明中国春不含有恢复基因。 在体细胞染色体数为42的331个不育系与UAD的杂种衍生后代中选到18个可育株,并对部分植株进行了细胞学鉴定。其中040-5、061-1和061-4与中国春的杂种F_1的育性分离和染色体配对情况表明它们是含有来自小伞山羊草染色体A上的恢复基因的杂合易位系。     

High-rate spontaneous reversion to cytoplasmic male sterility in sugar beet: a characterization of the mitochondrial genomes

Summary Among the fertile sugar beet lines with nuclear sterility maintenance genes, rf, in a homozygous recessive state, sublines capable of reverting spontaneously at a high rate to sterility were identified. Of 24 related fertile sublines studied, 6 were found to spontaneously revert to sterility with a frequency of about 19%. Genetic analysis confirmed the cytoplasmic nature of spontaneously arising sterility. Reversion to sterility in these sublines was accompanied by alterations in the mitochondrial genome structure: loss of the autonomously replicating minicircle c (1.3 kb) and changes in the restriction patterns of high-molecular-weight mitochondrial DNA (mtDNA). Southern hybridixation analysis with cloned minicircle c as a probe revealed no integration of this DNA molecule into the main mitochondrial and nuclear genomes of the revertants. Comparative BamHI and EcoRI restriction analysis of the mtDNA from the sterile revertants and fertile parental subline showed that the spontaneous reversion is accompanied by extensive genomic rearrangement. Southern blot analysis with cloned -subunit of F₁-ATPase (atpA) and cytochrome c oxidase subunit II (COX II) genes as probes indicated that the changes in mtDNA accompanying spontaneous reversion to sterility involved these regions. The mitochondrial genomes of the spontaneous revertants and the sterile analogue were shown to be identical.     

Bi- and trivoltine complex life cycles in a Kanto (Japan) population of a wild bruchid Kytorhinus sharpianus

The partial trivoltinism and overwintering of Kytorhinus sharpianus Bridwell (Coleoptera: Bruchidae) was studied in the Kanto district, Japan. The later in the summer eggs were laid by the first-generation adults, the higher was the incidence of larval diapause in the second generation. The incidence of diapause also fluctuated between years, influencing the abundance of third-generation larvae. A relatively large proportion of third-generation larvae did not attain the diapause stage by the beginning of winter. The diapause development of larvae in diapause was completed by mid-January. Immature larvae of the third generation also overwintered and emerged as adults in the spring.     

Two new loci for hybrid sterility in cultivated rice (Oryza sativa L.)

Female gamete abortion in Indica-Japonica crosses of rice was earlier identified to be due to an allelic interaction at the S-5 locus on chromosome 6. Recently, in other crosses of rice, similar allelic interactions were found at loci designated as S-7 and S-8, located on chromosomes 7 and 6 respectively. All of them are independent of each other. At the S-5 locus, Indica and Japonica rice have S-5 ⁱ and S-5 ^j alleles respectively and Javanicas, such as Ketan Nangka, have a neutral allele S-5 ⁿ .The S-5 ⁱ /S-5 ^j genotype is semi-sterile due to partial abortion of female gametes carrying S-5 ^j , but both the S-5 ⁿ /S-5 ⁱ and S-5 ⁿ /S-5 ^j genotypes are fertile. The S-5 ⁿ allele is thus a wide-compatibility gene (WCG), and parents homozygous for this allele are called wide-compatible varieties (WCV). Such parents when crossed with Indica or Japonica varieties do not show F₁ hybrid sterility. Wide-compatible parents have been used to overcome sterility barriers in crosses between Indica and Japonica rice. However, a Javanica variety, Ketan Nangka (WCV), showed typical hybrid sterility when crossed to the Indian varieties N22 and Jaya. Further, Dular, another WCV from India, showed typical hybrid sterility when crossed to an IRRI line, IR2061-628-1-6-4-3(IR2061-628). By genetic analyses using isozyme markers, a new locus causing hybrid sterility in crosses between Ketan Nangka and the Indicas was located near isozyme loci Est-1 and Mal-1 on chromosome 4, and was designated as S-9. Another new locus for hybrid sterility in the crosses between Dular and the IR2061-628 was identified and was found linked to four isozyme loci, Sdh-1, Pox-2, Acp-1 and Acp-2, on chromosome 12. It was designated as S-15. On the basis of allelic interactions causing female-gamete abortion, two alleles were found at S-9, S-9 ^kn in Ketan Nangka and S-9 ⁱ in N22 and Jaya. In the heterozygote, S-9 ^kn /S-9 ⁱ , which was semisterile, female gametes carrying S-9 ^kn were aborted. The hybrid of Dular and IR2061-628, with a genetic constitution of S-15 ^Du /S-15 ⁱ , was semi-sterile and the female gametes carrying S-15 ^Du were aborted. A Japonica tester variety, Akihikari, and an Indica variety, IR36, were found to have neutral alleles, S-9 nand S-15 n, at these loci, in addition to S-7 nand at S-7. The accumulation of three neutral alleles into a breeding line should help solve the hybrid sterility problem in wide crosses of rice.     

The phylogenetic relationships ofEeniella nana Smith,Batenburg-van der Vegte et Scheffers based on the partial sequences of 18S and 26S ribosomal RNAs (Candidaceae)

Summary Two strains ofEeniella nana were examined for their partial base sequences of 18S and 26S rRNAs. In the partial base sequences of 18S rRNA (prositions 1451 through 1618, 168 bases) the strains ofE. nana have five, five, four and eleven base differences with those ofDekkera bruxellensis (type species).D. anomala (andBrettanomyces anomalus),D. naardenensis andD. custersiana, respectively. In the 26S rRNA partial base sequencings (positions 1611 through 1835, 225 bases and positions 493 through 622, 130 bases) the base differences were 46, 43, 34 and 40 and the percent similarities were 53–54, 51–54, 56–57 and 51–53, respectively. The sequence data obtained are discussed phylogenetically and taxonomically, especially on retention of the generic nameEeniella.This paper is dedicated to Professor Herman Jan Phaff in honor of his 50 years of active research which still continues.Significance of the coenzyme Q system in the classification of yeasts and yeast-like organisms. Part LVIII. For part LVII, see ref. [20].