首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 7 毫秒
1.
Résumé Les corps allates dePeriplaneta americana L. implantés dans des nymphes à destinée imaginale deCalotermes flavicollis Fabr. déterminent la formation d'intercastes soldats sexués.Ces intercastes constituent une série complète d'individus, intermédiaires entre le soldat parfait et l'imago.De remarquables intercastes soldats sexués sont apparus; ces individus allient au type soldat des structures sexuelles imaginales permettant la ponte.La morphogenèse de type soldat s'accompagne d'un développement des ovaires. Il y a multiplication des ovocytes et le vitellus se dépose dans les ufs qui parviennent à maturité. L'action morphogénétique descorpora allata se double d'une action gonadotrope.L'implantation tardive de corps allates dans des nymphes proches de la mue engendre des pseudimagos dont l'activité sexuelle se manifeste précocement.A la lumière de ces expériences nous pouvons attribuer aux corps allates les fonctions suivantes: inhibition des structures imaginales, morphogenèse des structures propres au soldat, multiplication ovocytaire et vitellogenèse; de plus, il s'ajoute à ces fonctions un rôle déterminant dans le comportement sexuel.
Summary The implantation ofcorpora allata fromPeriplaneta americana L. into future imaginal nymphs ofCalotermes flavicollis Fabr. gives rise to Intercastes sexual-soldiers.Some Intercastes have, with the soldier type, imaginal sexual structures which allow egg-laying.The soldier morphogenesis is accompanied by a development of the ovaries; there is a multiplication of oocytes and storing of yolk in the mature eggs.The implantation ofcorpora allata into nymphs very close to imaginal moult gives rise to pseudimagos whose sexual activity shows early.
  相似文献   

2.
Des adultes et des larves deC. septempunctata ont été observés individuellement dans un champ de blé afin de préciser, au cours de la journée et en fonction de la saison, leur distribution sur le végétal, la durée des principales séquences de leur comportement et leurs relations avec les pucerons. Au début du printemps, cette espèce thermophile est présente sur le sol et sur les feuilles basses des talles où elle est très mobile. Les adultes font très fréquemment la toilette des appendices de la tête. En juin, la population larvaire et imaginale se regroupe sur la partie supérieure des talles où se trouvent les pucerons. A cette époque, l'immobilité domine. Ces variations de la distribution verticale sont confirmées par la position sur le végétal des proies capturées. Les données suggèrent que, dans les champs, cette coccinelle consacre peu de temps à son alimentation. Le faible nombre de proies ingérées pose le problème de la couverture de ses besoins trophiques. Summary Observations were made in a wheat field during daylight hours to determine how the vertical distribution of adults and larvae ofCoccinella septempunctata changed with season and in response to aphid populations on which this coccinellid feeds. In early spring, this thermophilic coccinellid (larvae and adults) remained close to the ground and on the lower part of tiller leaves where it was highly active. Adults frequently groomed their head appendages. By June, most adults and larvae were found on the upper parts of tillers, the area preferred by their aphid prey. The beetles remained close to such sites and hence their vertical distribution corresponded to that of the aphids on which they fed. The fact that the beetles appeared to spend most of their time resting and moving within wheat crops, and little time feeding, raises the question of how the larvae and adults satisfy their dietary needs.
  相似文献   

3.
A stastical analysis of the spatial orientation of gastropod shells in the Nerinea Bed shows that they are aligned parallel to the bedding plane (Fig. 6 A) but no preferential orientation of the direction of shells can be detected (Fig. 6 B). This fact and others exclude the possibility of an accumulation of shells by currents only: In some points the lower contact of the Nerinea Bed is gradational and even shells attacked by perforating algae or fungi are not abraded (Figs. 3, 4, 9). The matrix of the Nerinea Bed, a biopelsparite seems to favour the hypothesis that empty shells were concentrated by winnowing of the fine fraction, but the thickness of the accumulation prohibits a purely mecanical explanation of this kind. There can be no doubt that the Nerinea Bed reflects optimal ecological conditions which have led to a mass development. As it is very probable that Nerineids were sedentary organisms (Vogel 1968), it is tempting to explain the accumulation of shells by biologic factors only. Under optimal ecological conditions Nerineids perhaps lived in banks similar to oyster-beds or banks of Vermetids. Microfaunas and microfacies of the “Kimmeridgian” - “Portlandian” passage beds indicate a somewhat restricted environment thus confirming the conclusions ofHerm (1977) about Nerineids from the Upper Cretaceous Gosau-beds of the Eastern Alps. For local stratigraphy, the Nerinea Bed forms an ecostratigraphic marker-bed very useful in chronological correlations.  相似文献   

4.
Summary An attempt to associate chemical and biological control has been realised in an orchard of apple trees contamined by San Jose Scale. Prospaltella perniciosi has been liberated two years ago in the hope of controling population densities of its host, after some years. In 1961, after one hivernal spray, unapplied in the narrow plot whereP. perniciosi was liberated, a spray program has been planned against plant-diseases: applescab and applemildew and many pests:Carpocapsa pomonella, several species of aphids and mites, Tortricids. Aphelinus mali was liberated to check an outbreak ofEriosoma lanigerum, late in the spring (june). The first experiment resulted in a sufficient control by means of fungicides and a good enough protection against insects, exceptCarpocapsa in the case of the apple variety “Reinette of Canada” (the most readily attacked by this pest). The evolution of population density ofP. perniocisi was not influenced by the control measures, but efficacity of parasitism was not yet sufficient to bring scale population beneath “tolerance-limits”.   相似文献   

5.
6.
7.
8.
9.
10.
11.
12.
13.
Underscoring a functional relation between fat mass, skinfolds, under or overweight and the ‘ideal theoretical weight’, constitutes a fundamental datum in anthropology. Indeed, this relation, which differs according to age, sex, ethnic group and physical activity, provides information on the distribution of fat contained in the skinfolds, the under or overweight and the ‘ideal theoretical weight’. The value of this relation lies not only in limiting the use of the corpulence index (W/H2) as an indicator of fat mass, but above all in the importance of physical activity and in the existence of a significant change in the distribution of fat according to the factors mentioned above.  相似文献   

14.
15.
16.
Résumé Par un jeûne de trois jours ou par l'administration per os de réserpine(2 à 4 mg/kg) durant 15 à 24 jours, on a provoqué des ulcères d'estomac chez des rats. Une partie des bÊtes ainsi traitées fut exposée durant cette période et pendant 2 heures par jour à un air ionisé contenant 5.000 à 15.000 petits ions par cm3 d'air. Pour les animaux soumis au jeûne, la proportion d'ulcères se monte à 93% chez les bÊtes de contrÔle, alors qu'elle n'est que de 59% chez les bÊtes traÎtées par l'air ionisé. Pour les rats traÎtés à la réserpine, les proportions sont de 83,respectivement de 45%. On a en outre exposé 66 patients atteints d'ulcères d'estomac et d'intestins durant 12 à 15 jours et pendant 15 à 45 minutes par jour à un air contenant 5.000 à 10.000 petits ions négatifs par cm3 d'air. Pour 38 d'entre eux, la douleur et les autres symptÔmes avaient diminué ou disparu après le traitement.
Gastric ulcers were produced in rats by starvation for 3 days or the administration of reserpine (2 to 4 mg/kg) for 15 to 24 days. Some of the animals were exposed to ionized air for 2 hours daily during these periods(5,000 to 15,000 small negative ions/m3 air). The incidence of ulcer development was 93% in the untreated starved rats and 59% in those treated with ionized air; 83% in the animals treated with reserpine and 45% in those with additional ionized air treatment. In a clinical investigation 66 patients with peptic ulcer were exposed for 12 to 15 days to 5,000 to 10,000 small negative ions/m3 air daily. Pain and other symptoms were diminished or abolished after this treatment in 38 patients.

Zusammenfassung Bei Ratten wurden durch 3 Tage Hungern oder Behandlung mit Reserpin (2–4 mg/kg) wÄhrend 15 bis 24 Tagen Magenulcera provoziert. Ein Teil der Tiere wurde wÄhrend dieser Perioden 2 Std. tÄglich ionisierter Luft exponiert (5.000–15.000 kleine Ionen/m3 Luft). Die Ulcusrate betrug bei den unbehandelten Hungertieren 93%, bei den mit ionisierter Luft behandelten 59%; bei den Reserpin behandelten Tieren betrug sie 83% und bei den zusÄtzlich mit ionisierter Luft behandelten 45%. In der Klinik wurden 66 Patienten mit Magen-Darmulcera 12–15 Tage lang 15–45 min tÄglich mit 5.000 –10.000 neg. kleinen Ionen/m3 Luft behandelt. In 38 Patienten waren nach der Behandlung der Schmerz und die anderen Symptome abgeschwÄcht oder verschwunden.
  相似文献   

17.
18.
《Comptes Rendus Palevol》2014,13(7):637-645
From the end of 1830, Étienne Geoffroy Saint-Hilaire worked to prepare a book on thalattosuchians (Mesoeucrocodylia, Thalattosuchia) from the Jurassic of Normandy. This work, planned to be entitled “Histoire des crocodiliens renfermés dans le terrain oolithique”, was never completed. Searches in the archives of the central library of the “Muséum national d’histoire naturelle”, Paris, resulted in the rediscovery of the set of original drawings ordered by Geoffroy Saint-Hilaire to illustrate his book. These drawings, 21 in total, were executed by several artists working in the Muséum, including Jean-Charles Werner, Henri-Joseph Redouté, and Nicolas Hüet. Geoffroy Saint-Hilaire offered this collection of drawings to the French Academy of Sciences in March 1834. These drawings were then donated to the library of the Muséum in November 1924 by Alfred Lacroix. This iconographic collection is of the highest importance for the history of palaeontology in France as it depicts unknown specimens that were destroyed during World War II.  相似文献   

19.
20.
It has become clear in recent years that programmed cell death occurs spontaneously in the cycle of the seminiferous epithelium. Although apoptosis is a key phenomenon in the control of sperm production, the existence and role of apoptosis in ejaculated sperm cells remain controversial. Apoptosis — as determined by DNA fragmentation and ultrastructural analysis — is abnormally frequent in the sperm cells of the ejaculate of sterile men. In this review, we discuss the possible origins of DNA damage in ejaculated human spermatozoa and the consequences of this DNA damage when apoptotic spermatozoa are used for ICSI. Percentages of DNA fragmentation in human ejaculated sperm are correlated with fertilization rates after IVF or ICSI assay. Detection of DNA fragmentation in human sperm could provide additional information about the biochemical integrity of sperm and may be used in future studies for fertilization failures not explained by conventional sperm parameters. However, the analysis of new markers of apoptosis (Fas, ANNEXINE V) and molecular mechanisms is now necessary to assess the role of apoptosis in human ejaculated sperm cells.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号