Bragantia, Volume: 7, Issue: 11-12, Published: 1947
  • Estudo agrícola-tecnológico de diversas variedades de Phormium tenax Forster

    Medina, J. C.; Aguirre Júnior, J. M.; Correia, F. A.

    Abstract in English:

    In spite of the polymorphism of Phormium has long been known, no systematic attempt has been made until now to study comparatively the agricultural value and fiber quality of the varieties. This paper is concerned with preliminary results about leaf yield, fiber-content, und general growth of six varieties, of Phormium tenax Forster including a detailed fiber analysis. It is concluded that the varieties have shown strong differences in plant development and fiber qualities, suggesting that some of them would be much more suitable for the improvement of existing areas, and the establishment of new ones on a commercial basis.
  • Sôbre a meiose de Dysdercus mendesi bloete (1937) - Hemiptera, pyrrhocoridæ

    Mendes, Luiz O. T.

    Abstract in English:

    1 - The spermatogonia of Dysdercus mendesi Bloete have 16 chromosomes : 7 pairs of autosomes and 2 sex-chromosomes. 2 - After the last spermatogonia! division, the chromatin of the autosomes diffuses and the nucleoplasm assumes an uniform granulai- aspect ; each sex-chromosome is involved by a vesicle and stands well colored. 3 - While the chromatin of the autosomes starts to condense again, to form the long threads (that finnally are seen in a paired condition) the cycle of the sex-chromosomes is as follows : a) yet contained in the vesicles, they grow in size and become long rods ; b) the vesicles disappear, the sex-chromosomes move inside the nucleoplasm and come to be disposed longitudinally, close together. c) they touch each other, become fissured, and a tetradlike chromatic element is formed, which contracts itself, remaining always well colored. 4 - The hetero-pycnosis of the sex-chromosomes is observed through the whole grow phase of the spermatocyte I. 5 - The separation of the sex-chromosome tetrad, originating two independent sex-chromosomes, is observed in the early grow phase of the spermatocyte as well as during any other period of this phase. The latest separation is observed during the diffuse stage of the nucleus. 6 - When the autosomes are in diakinesis, the sex-chromosomes assume the aspect of chromosomes in pachytene. 7 - In metaphase I the autosomic tetrads are in a more condensed and colored condition than the sex-chromosomes. The sex-chromosomes move to the center of the autosome-forming circle, but there is no contact between them. 8 - In anaphase I it is observed 2 interzonal connections between each autosomic dyad ; some exceptions are observed. Only one interzonal connection is observed between the separating sex-chromosomes. Moving to the poles the sex-chromosomes also approximate one to the other. 9 - In telophase I the sex-chromosome touch each other, and fuse side-by-side, forming only one chromatic element. The line of fusion is well visible through the subsequent stages of meiosis. 10 - In metaphase II the autosomes are disposed at the equator. The sex-chromosome, dyad is also disposed at the equator, as well as at any other position. 11 - In anaphase II the separation of the auto.somes is normal, and it is seen only one interzonal connection between its halves. The sex-chromosome dyad do not separate and moves to one pole, always in precession. 12 - There are two classes of spermatids : a) with 7 autosomes ; b) with 7 autosomes plus the sex-chromosome dyad. 13 - During the first phases of the spermatogeneses the 7-autosomc containing nucleus presents a reticulated aspect ; the sex-chromosome-dyad containing nucleus shows this chromatic element well colored inside the reticulated nucleoplasm. 14 - The male of Dysdercus mendesi Bloete has 7 AA + XX chromosomes. NOTE - A discussion on the movements of the sex-chromosome and its cycle. as well as on some aspects of the pairing of the autosomes, is being prepared. It will be published in the near future. The female of Dysdercus mendesi Bloete has 2n = 14A+4X.
  • Estudos citológicos no gênero Arachis

    Mendes, A. J. T.

    Abstract in Portuguese:

    Tôdas as variedades de amendoim estudadas até o presente têm 2n = 40 cromossômios e pertencem à espécie A. hypogxa L. e à A. nambiquarx Hoehne. O autor do presente trabalho confirma essas contagens e revela a existência de espécies com 2n = 20 cromossômios, a saber : A. prostrata Benth (?), A. marginata Gardn., A. marginata Gardn. var. submarginata Hoehne, A. Diogoi Hoehne f. typica Hoehne, A. Diogoi Hoehne sub-espécie major Hoehne e A. villosulicarpa Hoehne. Além disso, o número 2n = 20 foi encontrado em mais uma espécie não identificada e 2n=40 em plantas de 7 grupos diferentes, cuja identificação também ainda não foi feita. Uma quimera cromossômica foi constatada em raiz de A. hypogsea, parte com 40 e parte com 80 cromossômios. O amendoim cultivado, à luz desta investigação e das provas genéticas constatadas por vários autores, deve ser encarado como tetraplóide e deve ter surgido espontâneamente no próprio centro de origem das formas diplóides (Estado de Mato Grosso).

    Abstract in English:

    All the varieties of peanuts previously studied have been found to have 2n=40 chromosomes and belong to the species Arachis hypogsea L. and A. nambiquarse Hoehne. In the present paper the author confirms the chromosome number previously reported and reveals the existence of other species of -peanuts having 2n = 20 chromosomes. The species having 2n = 20 chromosomes were found to be: A. prostrata Benth (?), A. marginata Gardn., A. marginata Gardn. var. submarginata Hoehne, A. Diogoi Hoehne f. typica Hoehne, .A. Diogoi Hoehne sub-esp. major Hoehne and A. villosulicarpa Hoehne. In eight different samples of peanuts seeds sent from the State of Mato Grosso, seven were found to have 2n =40 chromosomes and one sample had 2n = 20 chromosomes. Unfortunately it has not yet been possible to obtain the botanical classification of these peanut samples. A chromosomal chimaera observed in a root tip section of A. hypogxa showed sectors having 40 and 80 chromosomes. Based upon the genet ical studies made by several authors, and under the light of the present investigation, the cultivated peanut must be considered of a tetraploid nature. It seems likely that A. hypogxa probably arose spontaneously by chromosome doubling from diploid forms. It also seems probable that this took place in the State of Mato Grosso, Brasil, which is generally recognised as place where peanut plants are indigenous.
  • Comportamento dos cromossômios sexuais do Dysdercus mendesi na segunda divisão dos espermatócitos

    Jor, S. de Toledo Piza

    Abstract in English:

    In a previous, publication (3) the author described the behaviour of the sex-chromosomes, of Dysdercus mendesi Blöte Following conversation with Dr. Luiz O. T. Mendes, the author was simulated to reexamine the, slides and to study another new series of slides" As a result of these observations the¹ writer now concludes that in the division of the 2nd spermatocytes the sex-chromosomes pass undivided to one pole. Thus half of the spermatids receives a single compound element and half receives none. This is believed to be; similar to the conclusions reached by. Dr.. Luiz O. T. Mendes. Further studies will be made with respect to the nature of the compound element.
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