Impacto da adubação orgânica sobre a incidência de tripes em cebola.

Analisou-se a relação entre adubação orgânica e a incidência de Thrips tabaci Lind. em cebola (Allium cepa L), na EE de Ituporanga,entre agosto e dezembro de 1998. Os tratamentos foram determinados de acordo com a necessidade de N para a cultura pela análise de solo. Empregou-se como fonte orgânica diversos adubos fornecendo 75 Kg/ha de N (esterco suíno; adubo Barriga Verde proveniente de esterco de aves; composto orgânico; esterco de peru; húmus); 37,5 Kg/ha de N (metade da dose normal com esterco de suíno); as testemunhas foram adubação mineral fornecendo 30-120-60 kg/ha de N-P2O5-K2O e o dobro da dose (60-240-120 kg/ha de N-P2O5-K2O); e testemunha sem adubação. Nenhum tratamento apresentou incidência de T. tabaci superior à testemunha sem adubo. A adubação mineral em relação à orgânica não favoreceu significativamente a incidência de T. tabaci . O processo de conversão do manejo do solo da área experimental de convencional para orgânico pode ter favorecido a infestação similar do inseto entre tratamentos. No período de maior incidência de T. tabaci, a relação com nutrientes foi descrita por um modelo envolvendo K/Zn, B e N de maneira positiva. A correlação entre nutrientes e T. tabaci não foi linear na maioria das avaliações. A adubação orgânica pode substituir a adubação mineral na cultura da cebola, pois foi possível atingir níveis de produtividade similares para ambos tratamentos

Genetic influences on human fertility

A remarkable characteristic of human reproduction is the very high prevalence of spontaneous abortion, which frequently has been associated with major chromosomal abnormalities. The various forms of maternal–fetal red cell incompatibility and their potentially adverse effects on human fertility are well understood, and during the last 15 years of the twentieth century there was vigorous debate as to whether couples who share HLA-DR and/or HLA-B alleles are subfertile. The most common genetic disorders associated with primary infertility in females are the chromosome abnormality Turner Syndrome (monosomy X), and Stein–Leventhal Syndrome (poly-cystic ovarian disease) which has a more complex and somewhat poorly defined genetic aetiology. A much wider spectrum of genetic defects can cause infertility in males, including Klinefelter Syndrome, X-autosome reciprocal translocation, Y-chromosome micro-deletions, congenital absence of the vas deferens, most commonly observed as part of the cystic fibrosis phenotype, and obstructive azoospermia in patients with Young Syndrome. Successful pregnancies can be initiated in the majority of individuals with these disorders; for example, using donated oocytes or embryos in women with Turner Syndrome, and intracytoplasmic injection of sperm (ICSI) collected from men with Klinefelter Syndrome or congenital absence of the vas deferens. In some disorders, such as Y-linked microdeletions, there may be a high risk of transmission to progeny following fertilization via ICSI, which has caused concerns on dysgenic grounds. Preimplantation diagnosis has been used to monitor such embryos

The genetics of infertility

The eleventh Annual Workshop of the Biosocial Society will be held on Friday 8 May 1998 from 10.00 to 16.00 hours at the Department of Biological Anthropology, University of Cambridge, Downing Street, Cambridge

The benefits and limitations of the sperm quality analyzer IIB in assessing porcine sperm motility

The Sperm Quality Analyzer (SQA) IIB, a member of the SQA-II family of machines which uses the scatter of light by sperm as an indicator of sperm motility, was systematically evaluated as a means of analyzing objectively the motility of porcine epididymal sperm. The sperm motility (%) and the Sperm Motility Index (SMI) are calculated by the machine using pre-programmed algorithms designed for human sperm. The machine performed well and was able to detect changes in sperm motility under experimental conditions. However, two major limitations of this machine were identified, (i) the readings obtained were influenced by the concentration of the sperm suspension despite the actual sperm motility remaining constant, and (ii) the machine was unable to differentiate between progressive and non-progressive motility. It should therefore be recognized that (a) the sperm concentration must be kept constant in studies in vitro if differences between treatment groups are to be identified, and (b) the inability to separate progressive motility from that of total motility will restrict the usefulness of this and similar machines to studies monitoring changes in total motility alone