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Late Developmental Stages (late + developmental_stage)
Selected AbstractsLarval cannibalism during the late developmental stages of a facultatively gregarious encyrtid endoparasitoidECOLOGICAL ENTOMOLOGY, Issue 6 2009ALEJANDRO TENA Abstract. 1The larvae of many gregarious parasitoid species are usually non-aggressive when they develop in or on a host, but those of Metaphycus flavus are one of the few exceptions known. Herein we describe their aggressive behaviour and the conditions under which it occurs, using observations in which larval development and physical conflict within parasitised and superparasitised hosts were mapped daily. 2Metaphycus flavus larvae often engaged in physical conflict that resulted in consumption of the losing larvae (= cannibalism ) in superparasitised hosts, whereas such conflict and consumption occurred rarely when a single brood developed in a host. 3Cannibalism among M. flavus larvae only occurred after the host resources had become scarce. Typically it occurred after the sixth day of development (fourth-instar larvae) when the larvae in a clutch had separated from their aeroscopic plate and were freed of their attachment to the host's cuticle. 4Female larvae in the initial clutch appeared more aggressive than male larvae when a second clutch was allocated 4 h after the first clutch. The probability of a larva being attacked and consumed by a brood mate increased as the number of larvae increased in the host. This partial tolerance might allow the members of the initial brood to defend themselves from offspring of a superparasitising female (= competitors ). Such post-ovipositional regulation of brood size might be interpreted as high-density intolerance among female offspring. [source] Content of endoplasmic reticulum and Golgi complex membranes positively correlates with the proliferative status of brain cellsJOURNAL OF NEUROSCIENCE RESEARCH, Issue 4 2009David C. Silvestre Abstract Although the molecular and cellular basis of particular events that lead to the biogenesis of membranes in eukaryotic cells has been described in detail, understanding of the intrinsic complexity of the pleiotropic response by which a cell adjusts the overall activity of its endomembrane system to accomplish these requirements is limited. Here we carried out an immunocytochemical and biochemical examination of the content and quality of the endoplasmic reticulum (ER) and Golgi apparatus membranes in two in vivo situations characterized by a phase of active cell proliferation followed by a phase of declination in proliferation (rat brain tissue at early and late developmental stages) or by permanent active proliferation (gliomas and their most malignant manifestation, glioblastomas multiforme). It was found that, in highly proliferative phases of brain development (early embryo brain cells), the content of ER and Golgi apparatus membranes, measured as total lipid phosphorous content, is higher than in adult brain cells. In addition, the concentration of protein markers of ER and Golgi is also higher in early embryo brain cells and in human glioblastoma multiforme cells than in adult rat brain or in nonpathological human brain cells. Results suggest that the amount of endomembranes and the concentration of constituent functional proteins diminish as cells decline in their proliferative activity. © 2008 Wiley-Liss, Inc. [source] Red ,Anjou' pear has a higher photoprotective capacity than green ,Anjou'PHYSIOLOGIA PLANTARUM, Issue 3 2008Pengmin Li Photoprotective function of anthocyanins along with xanthophyll cycle and antioxidant system in fruit peel was investigated in red ,Anjou' vs green ,Anjou' pear (Pyrus communis) during fruit development and in response to short-term exposure to high light. The sun-exposed peel of red ,Anjou' had higher maximum quantum yield of photosystem II (FV/FM) than that of green ,Anjou' and both the sun-exposed peel and the shaded peel of red ,Anjou' had smaller decreases in FV/FM after 2-h high light (photon flux density of 1500 ,mol m,2 s,1) treatment than those of green ,Anjou'. At the middle and late developmental stages, the xanthophyll cycle pool size on a chlorophyll basis, the activity of superoxide dismutase, ascorbate peroxidase (APX), monodehydroascorbate reductase (MDAR), dehydroascorbate reductase (DHAR) and glutathione reductase (GR) and the level of reduced ascorbate and total ascorbate pool in the sun-exposed peel were either the same or lower in red ,Anjou' than in green ,Anjou', whereas the xanthophyll cycle pool size on a chlorophyll basis and the activity of APX, catalase, MDAR, DHAR and GR in the shaded peel were higher in red ,Anjou' than in green ,Anjou'. It is concluded that red ,Anjou' has a higher photoprotective capacity in both the sun-exposed peel and the shaded peel than green ,Anjou'. While the higher anthocyanin concentration along with the larger xanthophyll cycle pool size and the higher activity of some antioxidant enzymes may collectively contribute to the higher photoprotective capacity in the shaded peel of red ,Anjou', the higher photoprotective capacity in the sun-exposed peel of red ,Anjou' is mainly attributed to its higher anthocyanin concentration. [source] Cytoskeletal Changes in Oocytes and Early Embryos During in vitro Fertilization Process in MiceANATOMIA, HISTOLOGIA, EMBRYOLOGIA, Issue 1 2010E. Gumus Summary The cytoskeleton plays crucial roles in the development and fertilization of germ cells and in the early embryo development. The growth, maturation and fertilization of oocytes require an active movement and a correct localization of cellular organelles. This is performed by the re-organization of microtubules and actin filaments. Therefore, the aim of the present study was to determine the changes in cytoskeleton during in vitro fertilization process using appropriate immunofluorescence techniques. While the chromatin content was found to be scattered throughout the nucleus during the oocyte maturation period, it was seen only around nucleolus following the completion of the maturation. Microtubules, during oocyte maturation, were regularly distributed throughout the ooplasm which was then localized in the subcortical region of oocytes. Similarly microfilaments were scattered throughout the ooplasm during the oocyte maturation period whereas they were seen in the subcortical region around the polar body and above the meiotic spindle throughout the late developmental stages. In conclusion, those changes occurred in microtubules and microfilaments might be closely related to the re-organization of the genetic material during the oocyte maturation and early embryo development. [source] | ||||||||||