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1.
1. Time perception is seldom studied in invertebrates, with the limited experimental evidence being insufficient to provide a comprehensive pattern of the capacity of invertebrates to measure time and use it in decision‐making processes. 2. In this study, it was hypothesized that insect parasitoids have evolved the capacity to measure time precisely and to use it to optimize foraging decisions related to host exploitation. To examine time perception in females of the gregarious egg parasitoid Trichogramma euproctidis, the present study used their ability to adjust their investment (number of eggs laid) in a host to the initial transit duration (interval between the first contact with the host and the following contact with the substrate). Females utilize this method to assess host egg size, as a large egg necessarily requires more time to evaluate than a small host. In this study, the initial transit duration for a given sized egg was artificially extended by suspending it. 3. For similar sized hosts, female T. euproctidis significantly increased both oviposition duration and progeny allocation following a longer initial transit duration. 4. These results demonstrate the intrinsic capacity of this parasitoid to measure time and to adjust their progeny investment accordingly. This is believed to be one of the few demonstrations of a retrospective measure of time in an invertebrate. 相似文献
2.
Nutrient translocation in chestnut tree stemwood was calculatedfrom the distribution of nutrient content throughout the tissuelife-span. The dynamics of internal translocation were followedduring the crop rotation by means of an age series of five coppicedstands (219 years). N, P, K, Ca and Mg contents in treerings were estimated from the concentrations along a verticaland radial gradient and from the ring volume obtained usingstem ring analysis.Real nutrient translocation was calculatedstepwise between successive stages in the age series;apparenttranslocation was computed on a complete tree rotation by comparingthe initial content just after the ring was formed with themineral content in the oldest stand. There was a marked translocationof N, P, K and Ca when the rings were physiologically-activetissues. Real translocation of N, P and K (but not Ca) increasedwith stand age, obviously in parallel with the enlarged stemwoodbiomass reaching 23.2 and 20.6 kg ha-1for K and N in the lastyears of rotation, nearly 5 kg ha-1for Mg and about 3 kg ha-1forCa and P. Potassium was the most mobile element since translocationreached 60% of the total amount immobilized in the stemwoodat the end of the rotation, whereas values for N, P and Mg wereapproximately 25% and 10% for calcium. Total apparent translocationreached respectively 39.2 and 32.4 kg ha-1for K, N, approximately12 and 7 kg ha-1for Mg and Ca and only 4.4 kg ha-1for P. Totalapparent translocation as a percentage of total wood immobilizationwas 114% for K, 83% for Mg, 63% for P, but only 39% for N and24% for calcium. Translocation; nutrient content; stemwood; tree ring; coppice; age series; dynamics; chestnut tree; Castanea sativa Miller 相似文献
3.
The pair, duo-trio and triangle tests were compared, using three levels of instructions with orange drink as medium and sucrose as stimulus. If the subjects know only the nature of the test, the pair test cannot be performed and the frequencies of correct responses above chance of the two other tests do not differ significantly, in this case the triangle test is the more efficient. If the subjects know the nature of the test and the nature of the stimulus, the frequency of correct responses above chance obtained for the pair test is significantly higher than those of the two other tests, in this case the pair test is more efficient. Finally, if the subjects know the nature of the test, the nature of the stimulus and whether or not the sample to be selected contains the stimulus, the conclusions are more difficult to achieve but the triangle test seems to be the more efficient. 相似文献
4.
SEM Characterization of an Extracellular Matrix Around Somatic Proembryos in Roots of Cichorium 总被引:1,自引:0,他引:1
DUBOIS THERESE; DUBOIS JEAN; GUEDIRA MOUNA; DIOP ALIOUNE; VASSEUR JACQUES 《Annals of botany》1992,70(2):119-124
Roots of in vitro plantlets of a hybrid Cichorium intybus L.x C. endivia L. placed for 10 d in an agitated liquid inductionmedium in darkness at 35 °C give somatic embryos of varioussizes which disrupt the epidermis. Proembryos can be observedinside the root; they show a fibrillar network linking the surfacecells. The network is observed in agitated and static liquidmedium; it is not well developed on solid medium. It is notremoved by lipid solvents and pectinase but disappears partlywith protease. Ether-methanol (1:1 v/v) for 45 min and Tris-HC1buffer for 3 h at 30 °C destroy it. As in animal cells suchexternal proteic networks are constituents of an extracellularmatrix linked to the cytoskeleton, we tested microtubule destabilizationby colchicine and cold treatments which removed the network;this effect was reversed by DMSO and high temperature. Cichorium, extracellular matrix, extracellular proteins, somatic embryogenesis 相似文献
5.
JEAN F. MALCOLMSON 《The Annals of applied biology》1969,64(3):461-468
In leaves of potatoes inoculated with Phytophthora infestans early in the growing season, more but smaller lesions with later onset of sporulation and fewer sporangia developed than on those inoculated later. None of these factors was uniform on detached leaves of all clones, so could not be used separately to forecast field resistance satisfactorily; when considered together, a reasonable prediction was feasible. With some clones, tests of detached leaflets gave a better indication of behaviour in the field than laboratory tests of whole plants. 相似文献
6.
SYNOPSIS. An electron microscopic study is made of merozoites and schizogony of Eimeria magna and Eimeria tenella from rabbits and chickens infected 5 days before fixation.
The merozoite outer layer is formed by a unit membrane lined by a dense osmiophilic layer. A micropyle is present. The apical complex of the cell is constituted by a conoid surmounted by 2 rings and surrounded by another from which about 26 subpellicular, tubular fibrils start. Two "rhoptries" (= toxonemes) go thru the conoid to the apex of cell. Rare sarconemes (= convoluted tubes) are disseminated in the anterior part of merozoites. A nucleus with nucleolus, Golgi apparatus, mitochondria, endoplasmic reticulum, lipid globules and glucidic grains were observed.
Schizogony starts by the formation of a multinucleated schizont which has a centriolar structure. The new merozoites appear as evaginations of the schizont's membrane. Cellular organelles (conoid, rhoptries, micropyle, sarconemes) differentiate and the nuclei enter the diverticula of the schizont. Then the development of merozoites proceeds by "external budding".
The ultrastructural similarities between the merozoites of Eimeria and the endodyocytes of Toxoplasmea, appear to us to be extremely interesting and indicate a close relationship between the Toxoplasmea and the Coccidia. 相似文献
The merozoite outer layer is formed by a unit membrane lined by a dense osmiophilic layer. A micropyle is present. The apical complex of the cell is constituted by a conoid surmounted by 2 rings and surrounded by another from which about 26 subpellicular, tubular fibrils start. Two "rhoptries" (= toxonemes) go thru the conoid to the apex of cell. Rare sarconemes (= convoluted tubes) are disseminated in the anterior part of merozoites. A nucleus with nucleolus, Golgi apparatus, mitochondria, endoplasmic reticulum, lipid globules and glucidic grains were observed.
Schizogony starts by the formation of a multinucleated schizont which has a centriolar structure. The new merozoites appear as evaginations of the schizont's membrane. Cellular organelles (conoid, rhoptries, micropyle, sarconemes) differentiate and the nuclei enter the diverticula of the schizont. Then the development of merozoites proceeds by "external budding".
The ultrastructural similarities between the merozoites of Eimeria and the endodyocytes of Toxoplasmea, appear to us to be extremely interesting and indicate a close relationship between the Toxoplasmea and the Coccidia. 相似文献
7.
M. JEAN TWEEDIE 《American anthropologist》1968,70(6):1132-1142
Sometime between A.D. 1100 and 1600 a group of Athapaskan-speaking tribes migrated from northwestern North America into the southwestern United States, where most eventually came to be referred to as Apaches. Compared with the majority of Amerindian tribes, relatively little is known about this group, specially about their life prior to the arrival of Europeans in the seventeenth century. This paper is an attempt to gather together widely scattered information about their prehistoric movements, their economy, and their general style of adaptation to the Southwest. 相似文献
8.
Of the eleven cultivated species of Umbelliferae heavily attacked in the field by Cavariella aegopodii Scop., chervil (Anthriscus cerefolium) attracted so many alates that it was killed before a population of alienicolae developed. Carrot was next in order of alate preference and coriander (Coriandrum sativum) and caraway (Carum carvi) were last. Despite its lack of attraction, caraway proved more lastingly suitable as a host and eventually supported the largest population of alienicolae. Of the wild umbellifers tested, wild carrot, Daucus carota ssp. carota, was the species most preferred by the incoming alates and hemlock (Conium maculatum) the least. On hemlock, also, there was little colonization. Although a sequence of wild umbellifers supported C. aegopodii through most of the year, few were suitable winter hosts; the apterae hibernated largely on carrot crops. In spring, cow parsley (Anthriscus sylvestris) was one of the hosts first colonized by immigrant C. aegopodii and carried winged alienicolae before the end of June. The main development of winged alienicolae on Anthriscus and other wild Umbelliferae, however, was in July. The possible role of the wild umbelliferous hosts of C. aegopodii in the spread of motley dwarf virus to carrots is discussed. 相似文献
9.
JEAN VANNIER 《Lethaia: An International Journal of Palaeontology and Stratigraphy》1990,23(1):103-112
Leiocopes differ from all other major ostracode groups (e.g. Palaeocopa. Binodicopa, Podocopa, Myodocopa) mainly in having a simple rounded/convex shape and a strong (dorsal and/or ventral) asymmetry. These morphological features are highly conservative in leiocopes through the Palaeozoic (lower Ordovician-middle Devonian). Functional morphology and facies distribution suggest that typical 'dome-like' leiocopes (e.g. aparchitids) may have lived off the bottom in relatively deep water environments, contrasting with most (inferred) benthic Palaeozoic ostracodes (e.g. heavily calcified dimorphic palaeocopes). Reversely, smaller sized and both dorsally and ventrally asymmetrical leiocopes (e.g. Ordovician jaanussoniids) are considered as possible benthic dwellers with reduced mobility on or within the substratum. □ Ostracodes, Leiocopa, Aparchitidae, Jaanussoniidae. Palaeozoic. Ordovician, Silurian, Devonian, asymmetry, functional morphology. 相似文献
10.
The control of incompatibility in distylous Pulmonaria affinis Jordan (Boraginaceae) 总被引:1,自引:0,他引:1
A.J. RICHARDS JEAN MITCHELL 《Botanical journal of the Linnean Society. Linnean Society of London》1990,104(4):369-380
In P. affinis, pin pollen is shorter on average than thrum pollen. Pins have more coronal hooks on stigmatic papillae than thrums, but gaps between papillae are relatively smaller for thrums. Pin stigmas receive more pollen than thrum stigmas. Thrum stigmas receive more (dissortive) pin pollen, but pin stigmas are assortively pollinated. Pollen only germinates when trapped below papilla coronas. On thrum stigmas, most trapped pollen is pin. Pollen germination is better on thrum stigmas than pin stigmas, and thrum stigmas show a close relationship between numbers of legitimate pollen grains, numbers of germinating grains, and numbers of pollen tubes in the style. There is no inhibition of illegitimate pollen germination. Illegitimate pollen tubes are inhibited in the style. Incompatibility operates by a combination of dissortive pollination, dissortive pollen trapping, and stylar pollen tube inhibition. All heteromorphic features differing between pins and thrums are implicated in the inhibition of within-morph fertilization in thrums. 相似文献