Wyniki wyszukiwania

1

DMRT1-Dmrt1, the sex determining or sex differentiating gene in Vertebrata

100%

Bratus A., Slota E.

Folia Biologica

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2006

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tom 54

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nr 3-4

2

Plant sexual reproduction: Aspects of interaction, history and regulation

72%

Willemse M. T. M.

Acta Biologica Cracoviensia. Series Botanica

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2003

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tom 45

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nr 1

Sexual reproduction in angiosperms is an interactive process involving the sporophyte, gametophytes, embryo and endosperm as well as the environment, aimed at achieving pollination, fertilization and dispersal. This interaction occurs via an interface with nutrients and signals outside the cell and even outside the plant. Sexual reproduction has a history. In water, algae have different types of sex organs and gametes, and in some cases the female gamete stays on the plant. The zygote uses water movement and gravity for dispersal. Some algae have alternation of generations in the life cycle, and only the gametophyte functions in sexual reproduction. On land, ferns and mosses inherited alternation of generations, with oogamy and zygote development on the gametophyte, with wind dispersal of the meiospore. In angiosperms, heterospory and the retention of the megaspore, megagametophyte and embryo on the sporophyte lead to a seed with gravity and biotic dispersal. The history of sexual reproduction is based on sex determination, due to cross-fertilization and recombination. Sex differentiation is manifested in the increasing complexity of interaction in the nutrient supply, the retention of the gametophyte or even the embryo, and the type of vector of dispersal. Regulation of sexual reproduction in angiosperms is governed mainly by the sporophyte, with the expression of new genes for biotic pollination and seed dispersal. In the heterotrophic gametophyte some gene expression is suppressed. The development of sexual reproduction is due to the communication between the organism and a dynamic environment.

3

Genetyczne mechanizmy roznicowania gonad ssakow

58%

Brzezinska K., Kosowska B., Tokarska M., Moska M.

Acta Scientiarum Polonorum. Medicina Veterinaria

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2004

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tom 03

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nr 2

3-10

4

Winter diet of Great Pampa-finches Embernagra platensis in Guamini Lagoon, Argentina

58%

Montalti D., Ferman L. M., Camperi A. R., Soave G. E., Arambarri A. M., Darrieu C. A.

Acta Ornithologica

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2005

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tom 40

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nr 1

79-82

The diet of the Great Pampa-finch includes seeds rather than insects. Our objective was to study its diet during the winter season and, whenever possible, to record differences between the sexes in diet patterns. This species was studied at Guaminí Lagoon, Buenos Aires Province, Argentina. The stomach content of 38 adult birds was investigated. The analysis shows that the food eaten by E. platensis consisted of seeds (60%) (Chenopodiaceae, Asteraceae, Ciperaceae and Poaceae) and insects (39%) (Bellostomatidae, Dytiscidae, Curculionidae, Coccinelidae, Formicidae and Apidae). Males ate more insects and, overall, more items than females. These, in turn, consumed a greater amount of plants. Niche breadth values were 2.9 for males and 3.1 for females. The seeds encountered were those of plant species typically associated with the pampas.

5

Sex dimorphism in development dynamics and in development progression of morphological features in human foetuses

58%

Waszak M., Cieslik K.

Folia Morphologica

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2003

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tom 62

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nr 1

The study material comprised 3889 foetuses of both sexes, aged 20–42 weeks. t-Student test has been applied to evaluate the existence of potential sex-dependent differentiation of developmental trends as assessed by weekly measurements of selected somatic features and by the weight of internal organs. The regression coefficients of the analysed variables have been compared against the opposite sex. The rate of development of the analysed features in consecutive weeks has been found to be sex-related. Highest sex-related differences have been observed for the total body weight and for the weight of internal organs, with the exception of the adrenals, and the differences have been significant enough to justify the existence of contrasting, sex-dependent patterns of development of the analysed variables. The development of the analysed morphological features has been depicted by curvilinear regression. When described by various degree polynomials the development course of the analysed features displays sex-related differences. Only the change in the weight of the adrenals is similar for both sexes. The evaluation of the developmental advancement of the analysed features has revealed that they are usually at a more advanced development level in female foetuses.

6

The influence of temperature on the sex differentiation process in peled Coregonus peled [Gmel.]

58%

Krol J., Demska-Zakes K., Hliwa P., Korzeniowska G.

Archives of Polish Fisheries

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2003

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tom 11

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nr 1

The objective of this study was to examine the influence of water temperature (10,17 and 21ºC) on the sex differentiation process in peled. A high temperature, even a sub-lethal one, was not observed to have an influence on the sex ratio in this species; from day 81 after hatching until the end of the experiment the sex ratio in all three experimental groups was 1:1. It was noted, however, that thermal conditions determine the rate of sex differentiation and, in particular, of cytological differentiation. The first female-line cells, oogonia, were observed on day 102 after hatching in the peled kept in water at a temperature of 10ºC. Cytological differentiation was observed in the fish that were reared in higher temperatures as soon as day 81 after hatching. The first symptoms of anatomical differentiation were noted at this time in fish from all experimental groups. Two types of gonads were observed in histological cross-sections; one had a thicker anterior part with the generative and somatic parts located separately (ovaries), and the other had small, spindle-like gonads (future testes). No cytological differentiation of the male sex cells was observed during the experiment.

7

Induction of testis-ova in pikeperch [Sander lucioperca [L.]] exposed to 4-nonylphenol

58%

Demska-Zakes K., Zakes Z.

Archives of Polish Fisheries

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2006

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tom 14

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nr 1

The aim of the study was to evaluate the effect of nonylphenol (NP) administered in feed (trout pellets) on the growth rate, mortality, and morphological and histological gonad development of pikeperch. The oral administration of NP (0.0, 0.1, 1.0, 10.0, or 100.0 mg kg’ feed) to pikeperch juveniles (initial body weight of approximately 0.3 g; fish age 28 days post hatch (28 DPH)) for 7 to 63 days (35 - 91 DPH) did not affect fish mortality, growth, or condition. Histological and morphological studies revealed that the administration of NP (time of exposure over 28 days (fish age above 63 DPH)) at a dose 0.1 - 100 ppm significantly decreased the percentage of males and produced intersex fish. Abnormal gonads contained numerous small spaces resembling the ovocell of ovaries. Testis-ova contained both female and male germ cells. An increase in treatment dose and time of duration increased the percentage of intersex fish and decreased the percentage of males.

8

Influence of heavy metals and 4-nonylphenol on reproductive function in fish

51%

Popek W., Dietrich G., Glogowski J., Demska-Zakes K., Drag-Kozak E., Sionkowski J., Luszczek-Trojan E., Epler P., Demianowicz W., Sarosiek B., Kowalski R., Jankun M., Zakes Z., Krol J., Czerniak S., Szczepkowski M.

Reproductive Biology

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2006

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tom 06

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nr Suppl.1

Ograniczanie wyników

DMRT1-Dmrt1, the sex determining or sex differentiating gene in Vertebrata

Plant sexual reproduction: Aspects of interaction, history and regulation

Genetyczne mechanizmy roznicowania gonad ssakow

Winter diet of Great Pampa-finches Embernagra platensis in Guamini Lagoon, Argentina

Sex dimorphism in development dynamics and in development progression of morphological features in human foetuses

The influence of temperature on the sex differentiation process in peled Coregonus peled [Gmel.]

Induction of testis-ova in pikeperch [Sander lucioperca [L.]] exposed to 4-nonylphenol

Influence of heavy metals and 4-nonylphenol on reproductive function in fish