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21.
Bruce H. Jennings 《Agriculture and Human Values》1997,14(3):259-271
Over the past several decades, a group of scholars at the Berkeley campus of the University of California have frequently challenged many of the dominant themes of contemporary agricultural research. In their work, they have organized curricula questioning the assumptions of conventional agriculture and its sciences while encouraging the development of alternative agricultural practices based on principles of ecology. Their collective critique has stimulated an intellectual climate calling forth a scrutiny of the university's role in the production of knowledge and the social consequences of its works. The result of this intellectual project has been a group that has also largely challenged the dominant themes of the modern university. In place of a setting where ideas are a passive currency, the modern university is a place where knowledge and power are manifest in a dialectic that is revealed not simply by the production of knowledge, but its destruction as well. It is in this context that the recent history of a group of scholars at the University of California provides a striking testimony concerning the disturbing character of science in the modern university. The ecological and social dimensions of “killing fields” that captures the contemporary hazards of food and fiber production in California is also reflected in the gradual demise of a group of researchers at Berkeley who have endeavored to provide an alternative vision of agriculture. 相似文献
22.
JL Yaniz M Lopez-Bejar P Santolaria J Rutllant & F Lopez-Gatius 《Reproduction in domestic animals》2002,37(2):75-80
This review focuses on factors associated with the development of intraperitoneal insemination in mammals. Findings to date indicate that fertility improves as the sperm cell concentration rises, but that the optimal sperm number differs in each species. Sperm washing before intraperitoneal insemination favours fertility. Peritoneal fluid shows a variable effect on spermatozoa, depending on the hormonal status of the female. The optimal time for insemination appears to be just prior to ovulation. The technique may be performed either through the abdominal or the vaginal wall. Verification of sperm deposition in the proximity of the ovaries improves fertility rates. Although associated with some risk of infection and an immune reaction against spermatozoa, the intraperitoneal technique rarely gives rise to severe anaphylactic shock, peritonitis, adhesion formation and the production of anti‐sperm antibodies and these complications may be prevented by adequate sperm pretreatment and antibiotic therapy. The success of intraperitoneal insemination in humans, with results comparable with those of intrauterine insemination in the treatment of infertility, suggest the potential use of this technique in domestic mammals, especially in those in which intrauterine insemination poses practical difficulties. Some of the methods applied in human intraperitoneal insemination, such as confirming the position of the needle in the peritoneal cavity, and sperm pre‐treatments might also improve results in domestic species. Conversely, the use of the animal model should help to develop some aspects of this technique in humans. 相似文献
23.
D. L. Jennings 《Euphytica》1982,31(3):953-956
Summary Gene H determines cane hairyness in raspberries and was reported to facilitate escape from infection by Botrytis cinerea and Didymella applanata. However, experiments with mycelial inoculations of wounded canes showed that it conferred a form of resistance which was evident for a long period after the establishment of infections by these pathogens. The gene also contributed to the resistance of fruit to B. cinerea and of canes to Leptosphaeria coniothyrium. Alternative hypotheses to explain these observations are discussed: two based upon its possible genetic linkage with a gene or genes for resistance and one based upon its possible pleiotropic effects. 相似文献
24.
D. L. Jennings 《Euphytica》1963,12(2):229-243
Raspberry varieties can be classified into four groups on the basis of the extent to which outcrossing is thought to have occurred in their evolution. The groups are considered to differ in genetic structure, particularly in respect of the amount of inbreeding which they will tolerate without showing inbreeding depression. The immediate task of the breeder is largely to incorporate major genes for specific improvements while retaining and stabilising the good qualities already present. The achievement of this stability through inbreeding is most easily obtained in varieties which, by the nature of their origin, are able to give good phenotypic performance following inbreeding. The alternatives of basing new varieties on F1 hybrids or on material selected for inbreeding tolerance are discussed: it is concluded that F1 hybrids should be more easy to produce and may have the advantage of possessing greater developmental stability. Some evidence for this is presented.Three possible explanations are discussed for the frequent occurrence of heterozygosity at the gene loci H:h (hairy: non-hairy canes) and T:t (pigmented canes and red fruits: non-pigmented canes and yellow fruits) but is is unlikely that heterozygosity at these loci is important for cultivated varieties. It is suggested that virus resistance may play an important role in the breeding system of the species: if this is so, high levels of resistance may not always be desirable in wild populations, and their occurrence in a cultivated variety may therefore be influenced by the nature of the variety's origin. Protection against fungal diseases of the canes, however, is unequivocally desirable in both wild and cultivated raspberries. Since escape from two diseases of this kind is favoured by the presence of cane hairs (gene H), the choice of forms with sub-glabrous canes (gene h) for many modern varieties has perhaps been unfortunate. 相似文献
25.
Summary Varying degrees of resistance to cane spot were recorded among red raspberries in two cultivar trials and in 15 segregating families. The inheritance of resistance was studied, and the effect of gene H which determines the presence of cane hairs was assessed in eight of the families. The 0 to 5 scale used to record disease incidence was found to approximate to a logarithmic scale for the range of 0 to 93 cane spots per cane. Gene H and h phenotypes averaged scores of 3.05 and 2.42 respectively, but other genes independent of these had more influence on resistance. The latter genes appeared to be largely dominant. The possibility is discussed that one of them was a major gene with a large effect, but the evidence was equivocal in the absence of discontinuity in the expression of resistance. Resistance to yellow rust was studied in five of the families and was highly correlated with resistance to cane spot. Gene H had more influence on this disease, the mean counts of telia per unit leaf area for H and h segregates being 17.1 and 4.1 respectively. 相似文献
26.
Jennings HS 《Science (New York, N.Y.)》1924,59(1515):39-40
27.
Flasar FM Achterberg RK Conrath BJ Pearl JC Bjoraker GL Jennings DE Romani PN Simon-Miller AA Kunde VG Nixon CA Bézard B Orton GS Spilker LJ Spencer JR Irwin PG Teanby NA Owen TC Brasunas J Segura ME Carlson RC Mamoutkine A Gierasch PJ Schinder PJ Showalter MR Ferrari C Barucci A Courtin R Coustenis A Fouchet T Gautier D Lellouch E Marten A Prangé R Strobel DF Calcutt SB Read PL Taylor FW Bowles N Samuelson RE Abbas MM Raulin F Ade P Edgington S Pilorz S Wallis B Wishnow EH 《Science (New York, N.Y.)》2005,307(5713):1247-1251
Stratospheric temperatures on Saturn imply a strong decay of the equatorial winds with altitude. If the decrease in winds reported from recent Hubble Space Telescope images is not a temporal change, then the features tracked must have been at least 130 kilometers higher than in earlier studies. Saturn's south polar stratosphere is warmer than predicted from simple radiative models. The C/H ratio on Saturn is seven times solar, twice Jupiter's. Saturn's ring temperatures have radial variations down to the smallest scale resolved (100 kilometers). Diurnal surface temperature variations on Phoebe suggest a more porous regolith than on the jovian satellites. 相似文献
28.
Jennings HS 《Science (New York, N.Y.)》1941,94(2446):447-453
29.
30.
Reddien PW Oviedo NJ Jennings JR Jenkin JC Sánchez Alvarado A 《Science (New York, N.Y.)》2005,310(5752):1327-1330
We have identified two genes, smedwi-1 and smedwi-2, expressed in the dividing adult stem cells (neoblasts) of the planarian Schmidtea mediterranea. Both genes encode proteins that belong to the Argonaute/PIWI protein family and that share highest homology with those proteins defined by Drosophila PIWI. RNA interference (RNAi) of smedwi-2 blocks regeneration, even though neoblasts are present, irradiation-sensitive, and capable of proliferating in response to wounding; smedwi-2(RNAi) neoblast progeny migrate to sites of cell turnover but, unlike normal cells, fail at replacing aged tissue. We suggest that SMEDWI-2 functions within dividing neoblasts to support the generation of cells that promote regeneration and homeostasis. 相似文献