Intra-tree foraging behavior of Ceratitis capitata flies in relation to host fruit density and quality

We examined the intra-tree foraging behavior of individually-released, wild-population Mediterranean fruit flies (medflies), Ceratitis capitata (Wiedemann), on field-caged host trees bearing each of three different densities (0, 3, or 12 per tree) of non-infested host fruit (kumquat) or each of two levels of fruit quality (12 non-infested fruit or 12 fruit infested with eggs and covered with host marking pheromone). With increasing density of non-infested fruit, medflies tended to remain longer in trees, visit more fruit before leaving, oviposit more often, accept a proportionately smaller number of fruit visited, and emigrate sooner after the last egg was laid (i.e. have a shorter Giving-Up-Time). Medflies spent much less time, oviposited much less often, and exhibited a longer Giving-Up-Time on trees harboring pheromone-marked fruit than non-infested fruit. Variation in temperature within the range at which experiments were conducted (25–36°C) had little detectable influence on foraging behavior. We compare our findings with published findings on the intra-tree foraging behavior of another tephritid fly, Rhagoletis pomonella (Walsh), and with current foraging behavior theory. We discuss implications of our findings with respect to medfly management strategies, particularly fruit stripping in eradication programs and use of synthetic marking pheromone for control.

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Résumé Nous avons étudié le comportement de prospection dans un arbre, de femelles d'une population sauvage de C. capitata, libérées individuellement à l'intérieur de cages contenant des Eriobotrya japonica (kumquat), portant chacun 3 densités différentes de fruits no contaminés (0, 3, 12 par arbre) et chacun 2 niveaux de qualité de fruits: 12 fruits non infestés ou 12 fruits contaminés par des oeufs et recouverts de phéromone de marquage de l'hôte. C. capitata avait terndance à rester plus longtemps dans les arbres, à visiter plus de fruits avant le quitter, à pondre plus souvent, à accepter proportionnellement un nombre plus réduit de fruits déjà visités, à émigrer plus tôt après la ponte du dernier oeuf (c'est-à-dire à présenter un temps d'abandon plus bref), quand la densité des fruits non contaminés augmentait. C. capitata a dépensé beaucoup moins de temps, pondu beaucoup moins souvent, et présenté un temps d'abandon plus long sur les arbres portant des fruits marqués par la phéromone que sur ceux ayant des fruits non contaminés. Les variations de température dans la gamme de cells où les observations ont eu lieu (23–36°C) n'ont eu qu'une faible influence décelable sur le comportement de prospection. Nous avons comparé nos résultats avec ceux publiés sur la prospection à l'intérieur de l'arbre par une autre téphritide (Rhagoletis pomonella) et avec la théorie dominante sur le comportement de prospection. Nous discutons les conséquences de nos résultats sur les stratégies de lutte contre C. capitata, en particulier l'élimination des fruits dans les plans d'erradication et l'utilisation de phéromone synthétique de marquage.

     

Biogenesis of very-low-density lipoproteins in rat liver. Intracellular distribution of apolipoprotein B

The hepatic subcellular distribution of apolipoprotein B (apo B) was studied quantitatively by using an enzyme immunoassay developed for apo B and by immunoadsorption-precipitation of [3H]leucine-labelled apo B. Over 50% (of 0.59 microgram/mg protein) of the apo B was located in the microsomal fraction. Further subfractionation of the microsomes revealed that 47% of the microsomal apo B was in the Golgi apparatus, while another 43% was associated with the rough endoplasmic reticulum. The smooth endoplasmic reticulum accounted for only 4% of the total. When rat livers were labelled with [3H]leucine for 10 min, the rough endoplasmic reticulum accounted for 80% of the total immunoadsorbed precipitable apo B radioactivity while the smooth accounted for 20%, with no contribution from the Golgi. However, only 8.7% of the total radioactive immunoadsorbed precipitable apo B was lipoprotein-associated, the remainder being membrane-bound. Lipoprotein-associated apo B radioactivity in the smooth endoplasmic reticulum accounted for 40%, with the rough contribution attributed at 50% and the Golgi at 9%. We concluded that (a) there are two major pools of apo B in rat liver microsomes; (b) although the apo B mass may be negligible in the smooth endoplasmic reticulum, the latter does play a role in lipoprotein biogenesis. The possible function of apo B associated with membranes of the microsomes is also discussed.     

Unexpected thymic hyperplasia in transgenic mice harboring a neuronal promoter fused with simian virus 40 large T antigen.

The hypothalamic peptide growth hormone-releasing factor (GRF) regulates the secretion and production of growth hormone from the anterior pituitary (M. C. Gelato and G. R. Merriam, Annu. Rev. Physiol. 48:569-591). To study GRF gene regulation, transgenic mice were generated that harbor the human GRF promoter fused to the coding sequences from the simian virus 40 early region. These mice had normal hypothalamic functions but unexpectedly suffered from severe thymic hyperplasia. Immunohistochemical analysis revealed that large T antigen was expressed in the thymic epithelial cells. These cells have endocrine properties and are known to produce thymic hormones [corrected]. The thymic hyperplasia was the apparent consequence of inappropriate production of T-cell maturation factors by epithelial cells and could involve increased self renewal of apparently normal T stem cells in the thymus.     

Alteration of protein phosphorylation patterns in cell lines morphologically transformed by human cytomegalovirus

Human fibroblastic cell lines morphologically transformed by either live virus or DNA fragments of human cytomegalovirus had altered plasma membrane protein composition; quantitative changes, and gains and losses in protein composition in comparison to normal parent cell lines were detected. These transformed cell lines showed altered total cell protein phosphorylation patterns when compared to parent cell lines. A two to four fold increase in in vivo protein phosphorylation at serine and threonine residues was observed; no increase in phosphorylation at total cell tyrosine residues was detected. Analysis of the in vivo phosphorylated protein by two dimensional gel electrophoresis revealed some similarities as well as differences in the types of polypeptides phosphorylated between transformed and control cell lines. Increased (two-to sixfold over parent cell extracts) casein kinase and polyamine dependent casein kinase activities were detected in HCMV transformed cell extracts.     

Posttreatment with sodium arsenite is coclastogenic in log phase but not in stationary phase

Summary Posttreatment with sodium arsenite in log phase synergistically increases the chromosomal aberrations induced by ethyl methanesulfonate in Chinese hamster ovary cells, human fibroblasts, and human lymphocytes. However, posttreatment with sodium arsenite in stationary phase has no apparent effect on the clastogenicity of ethyl methanesulfonate. These results indicate that the cycling state of the cell plays a crucial role in the action of arsenite coclastogenicity. One prediction from this finding is that in combined treatment, posttreatment with sodium arsenite should preferentially kill cancer cells.     

嘉兰栽培及其秋水仙碱含量测定

嘉兰原属热带性地区的植物,但从云南南部引种到广州地区种植。表现生长发育良好,且其秋水仙碱含量高达0.40—0.45％。是一种有推广种植价植的药用植物。     

广西北部罗汉果根结线虫病研究

罗汉果根结线虫是罗汉果的一个重要病害。在室内盆栽接种条件下,该线虫年发生6代。本文叙述了线虫的生物学及其寄主植物。防治试验结果表明。穴施灭克磷等是有效的。土壤翻晒也能消灭大部分土中线虫,病薯用热处理也有很好的效果。     

中药灵香草及其混淆品种的比较鉴别

本文比较了中药灵香草Lysimachia foenum-graecum Hance及其混淆品种垂花香草Lysimaehia nutantiflora Chen et C.M.Hu的植物形态、药材性状以及茎、叶组织显微特征。指出垂花香草无灵香草特有的芳香。也无药用记载。应仔细区别,不宜混用。     

Gene deletion, a mechanism of induced mutation by arabinosyl nucleosides

9-β- -Arabinofuranosyl-2-fluoroadenine (F-ara-A) and 9-β- -arabinofuranosyladenine (ara-A) are purine nucleoside analogues which are incorporated into nucleic acids. This study demonstrates the mutagenic properties of F-ara-A and ara-A and provides evidence for mechanisms by which the arabinosyl nucleosides induce mutation. At the drug dosages that evoked exponential cell killing, F-ara-A and ara-A caused a significant increase in the number of 6-thioguanine-resistant mutants in Chinese hamster ovary cells. Southern analyses showed that 15 of 16 drug-induced mutants had lost all or part of the HPRT gene, whereas no loss of the gene was found in 4 spontaneous mutants. We conclude that both F-ara-A and ara-A induced mutation predominantly by causing deletion of genetic method. The remarkable frequency of gene deletion among these drug-induced mutations is discussed with respect to possible mechanisms of action of arabinosyl nucleosides in mutational studies.