Use of time in a decision‐making process by a parasitoid

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.     

Internal Nutrient Translocation in Chestnut Tree Stemwood: III. Dynamics Across an Age Series of Castanea sativa (Miller)

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 (2–19 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     

The Ordovician-Silurian boundary stratotype: consequences of its approval by the IUGS

Lespérance, Pierre J., Barnes, Christopher R., Berry, William B. N., Boucot, Arthur J. & Mu En-zhi 1987 07 15: The Ordovician-Silurian boundary stratotype: consequences of its approval by the IUGS.
The Ordovician-Silurian stratotype at Dob's Linn, Scotland is the second systemic boundary approved by the International Union of Geological Sciences (IUGS). A review of the internationally accepted criteria required of a stratotype shows that few of these are possessed by the Dob's Linn section. The strongest attribute of the section is the presence of zonal graptolites, although the boundary is recognized primarily on a single biological event (base of acuminatus Zone) for which the evolutionary relationships of the taxa are not established. In approving this boundary proposal in 1985, which received only simple majority support within the Ordovician-Silurian Boundary Working Group (OSBWG) and which fails to meet most of the accepted prerequisites for a stratotype, the International Commission on Stratigraphy (ICS) and the IUGS have established an unfortunate precedent. It follows that future systemic boundaries need not meet the accepted standards. It raises serious questions on the assessment and voting procedures of the International Commission on Stratigraphy and on the credence accorded the recommendations developed by the International Subcommission on Stratigraphic Classification of IUGS.     

COMPARISON OF THE EFFICIENCY OF PAIR, DUO-TRIO AND TRIANGLE TESTS

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.     

SEM Characterization of an Extracellular Matrix Around Somatic Proembryos in Roots of Cichorium

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     

In Vitro Production of Metacyclic Forms of Trypanosoma musculi and Their Infectivity in CBA Mice1

ABSTRACT. Bloodstream forms of Trypanosoma musculi, cultured in Schneider's drosophila medium at room temperature, multiply and differentiate through a series of developmental stages into infective metacyclic trypomastigotes in 10 days. Oral inoculation with these culture forms into CBA mice produced a parasitemia similar to that produced by intraperitoneal infection with bloodstream forms except for a three-day longer prepatent period. Attempts to induce parasitemia with bloodstream forms given orally were unsuccessful.     

“Pleiotypic Response”

A hypothesis has been developed to relate stringent control in bacteria to a set of interactions involved in the regulation of growth of transformed and untransformed mammalian cells.     

Factors involved in resistance to blight (Phytophthora infestans (Mont.) de Bary) in potatoes and assessment of resistance using detached leaves

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.     

Etude Ultrastructurale des Mérozoites et de la Schizogonie des Coccidies (Eimeriina): Eimeria magna (Perard 1925) de I'Intestin des Lapins et E. tenella (Railliet et Lucet, 1891) des Coecums des Poulets

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.     

Notes on the History and Adaptation of the Apache Tribes

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.