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Bohumil Mandk  Petr Pys ek 《Flora》2005,200(6):516-526
Atriplex sagittata is an annual, heterocarpic species producing three types of fruits, (i) dormant ebracteate (further termed type A), (ii) dormant bracteate (type B) and (iii) non-dormant bracteate (type C). In this study, we investigated populations grown from particular fruit types under different density regimes, and assessed their fate in particular life stages throughout a complete growing season. Differences in germination date among populations grown from seeds of the three fruit types were found, followed by differences in population density and plant size. Low population density and total biomass was recorded in populations of types A and B fruit (which are smaller and exhibit less germination), but the low density was not associated with faster growth of individual plants. Type C fruit, with bigger seeds and higher germinability, generated populations with higher densities and higher total biomass than populations generated from type A and B. There was a significant effect of plant density on dry weight of individual plants, regardless of the fruit type from which they were grown. Under both density regimes, plants grown from types A and B fruit were lighter than those grown from type C fruit. Plants grown from different fruit types produced dispersal units (fruits+bracteoles) of different mean weight which increased from A to B to C. However, the total fruit weight was not significantly different when plant size was used as a covariate. Maternal effect on seed germinability, exhibited by plants grown from the three fruit types, was not significant. However, a remarkable trend was found. Lower germination was recorded in type A and B fruits produced by plants which grew under higher densities. It is concluded that plants derived from different fruit types differ in growth characteristics and population parameters which can have pronounced effect on the life cycle and population regeneration in successive years.  相似文献   
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The objective of this study was to compare the thermoregulatory responses of rabbits to fever-inducing doses of various cytokines (IL-1β, IL-6, TNF-α) injected peripherally (i.v.), or centrally (i.h.).TNF-α (1 μg kg−1), when applied i.v. at thermoneutral conditions, induced a long lasting increase in hypothalamic temperature, which reached maximal values within 50 min and then persisted for at least 3 h. This monophasic fever-like response was due to extensive and long lasting attenuation of panting and due to transient vasoconstriction. Metabolic rate tended to increase during the early phase of the fever, only. On the other hand, IL-6 when applied i.v. in the same dose (1 μg kg−1) and IL-1β, in a much lower dose (60 ng kg−1), induced a short lasting monophasic hyperthermia due to transient attenuation of panting and due to transient vasoconstriction. No significant increase in metabolic rate was observed. The immediate attenuation of panting and induction of vasoconstriction rather resembled reflex (shock) responses than specific thermoregulatory reactions. Thirty minutes after i.v. administration of TNF-α, temperature thresholds for induction of cold thermogenesis, panting and vasomotion were shifted to higher body temperatures and remained elevated for at least 3 h. In case of IL-1β the increased temperature thresholds were observed 30 min after i.v. administration, only. I.v. applied IL-6 did not influence the thresholds neither 30 or 180 min after injection. Thus, peripheral IL-6 rather induced hyperthermia than fever.When injected i.h. all cytokines studied induced a long lasting increase in body temperature similar to that after i.v. injection of LPS. Temperature thresholds for induction of all thermoregulatory outputs were increased and remained increased for at least 3 h. No changes in hypothalamic thermosensitivity were observed. Data indicate a nonspecific effect of central cytokines on body temperature control.IL-1β appeared to be the most potent fever inducer. Nanogram doses of IL-1β injected i.v. induced a similar febrile response as microgram doses of other cytokines. On the other hand, TNF-α induced a longer lasting fever than other cytokines.  相似文献   
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The adaptation to chronic hypoxia confers long-lasting cardiac protection against acute ischemia–reperfusion injury. Protein kinase C (PKC) appears to play a role in the cardioprotective mechanism but the involvement of individual PKC isoforms remains unclear. The aim of this study was to examine the effects of chronic intermittent hypoxia (CIH; 7,000 m, 8 h/day) and acute administration of PKC-δ inhibitor (rottlerin, 0.3 mg/kg) on the expression and subcellular distribution of PKC-δ and PKC-ε in the left ventricular myocardium of adult male Wistar rats by Western blot and quantitative immunofluorescence microscopy. CIH decreased the total level of PKC-ε in homogenate without affecting the level of phosphorylated PKC-ε (Ser729). In contrast, CIH up-regulated the total level of PKC-δ as well as the level of phosphorylated PKC-δ (Ser643) in homogenate. Rottlerin partially reversed the hypoxia-induced increase in PKC-δ in the mitochondrial fraction. Immunofluorescent staining of ventricular cryo-sections revealed increased co-localization of PKC-δ with mitochondrial and sarcolemmal membranes in CIH hearts that was suppressed by rottlerin. The formation of nitrotyrosine as a marker of oxidative stress was enhanced in CIH myocardium, particularly in mitochondria. The expression of total oxidative phosphorylation complexes was slightly decreased by CIH mainly due to complex II decline. In conclusion, up-regulated PKC-δ in CIH hearts is mainly localized to mitochondrial and sarcolemmal membranes. The inhibitory effects of rottlerin on PKC-δ subcellular redistribution and cardioprotection (as shown previously) support the view that this isoform plays a role in the mechanism of CIH-induced ischemic tolerance.  相似文献   
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Hematopoiesis is the process by which hemocytes mature and subsequently enter the circulation. Vertebrate prokineticins (PKs) are known to take part in this process, as are the invertebrate prokineticin domain proteins, astakines. In Pacifastacus leniusculus, astakine 1 is essential for the release of new hemocytes into the open circulatory system of these animals. In addition to astakine 1, we have now cloned a homologue of astakine 1 with an insert of 13 amino acids, named as astakine 2. Both crustacean astakines lack the N-terminal AVIT motif, which is present in vertebrate PKs, and hence receptor binding differs from that of vertebrate PKs. We have found astakine-like sequences in 19 different invertebrate species, and the sequences show that some motifs are conserved among invertebrate groups. Previously we showed that astakine 1 is directly involved in hematopoiesis, and now we show that astakine 1 and astakine 2 have different roles in hemocyte lineage differentiation. Astakine 1 can stimulate proliferation of hematopoietic tissue (Hpt) cells (precursor of hemocytes) as well as specifically induce differentiation of Hpt cells along the semigranular cell lineage, whereas astakine 2 plays a role in granular cell differentiation. Moreover, we discuss the impact of the putative structures of different astakines in comparison with the vertebrate prokineticins.  相似文献   
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The regurgitation of metacyclic stages from the sand fly cardia is thought to be the prevailing mechanism of Leishmania transmission. This regurgitation may result through damage of the stomodeal valve and its mechanical block by the parasites. We found this phenomenon in three sand fly-Leishmania models and also in avian trypanosomes transmitted by Culex mosquitoes. Phlebotomus duboscqi, Phlebotomus papatasi, Lutzomyia longipalpis, and Culex pipiens were membrane-fed on blood containing Leishmania major, Leishmania chagasi (syn. infantum) and an unidentified avian Trypanosoma from Trypanosoma corvi clade, respectively. Females with the late-stage infections were processed for the optical and transmission electron microscopy. Localization of the parasites and changes to the stomodeal valve were in some aspects similar in all vector-parasite pairs studied: (i) a large plug of flagellates was observed in cardia region, (ii) parasites were attached to the chitin lining of the stomodeal valve by the formation of zonal hemidesmosome-like plaques. Leishmania promastigotes were found both attached to the valve as well as unattached in the lumen of midgut. The stomodeal valve of infected sand flies was opened, its chitin lining was destroyed and the unique filamentous structures on the apical end of cylindrical cells were degraded. In the Culex-Trypanosoma model, the whole population of epimastigotes was found in close contact with the chitin lining, and degenerative changes of the valve were less pronounced. We suggest that the phenomenon involving a blocked valve facilitating the regurgitation of parasites into the vertebrate host may occur generally in heteroxenous trypanosomatids transmitted by the bite of nematoceran Diptera.  相似文献   
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Phlebotomus sergenti populations from different areas of the Mediterranean basin are known to exhibit high intraspecific variability. Previous studies of ITS2 revealed the presence of two branches that may represent sibling species. To corroborate this finding by other tools, two colonies of P. sergenti originating from Turkey and Israel, each belonging to a different ITS2 branch, were compared by three different methods: geometric morphometric analysis of wing shape, RAPD (random amplified polymorphic DNA), and cross-mating study. For geometric morphometric analysis, two-dimensional Cartesian coordinates of 16 landmarks from the wings were digitized and analyzed. Significant shape differences were found between colonies but not between sexes within each colony. RAPD results formed two distinctive clades corresponding to the origin of the colony but also showed heterogenity among members of both colonies. In cross-mating studies, viable hybrid F1 and F2 progeny were obtained when both Turkish males/Israeli females and Israeli males/Turkish females were crossed. F1 progeny was included in RAPD analysis and these hybrids formed a distinctive clade with an intermediate position between the two parental clades. No significant differences were found in egg production of crossed sand flies. The cross-mating study showed that there is no reproductive barrier between P. sergenti from different geographical areas. On the other hand, RAPD and geometric morphometric analysis revealed a significant difference between colonies and confirmed the suitability of previous ITS2 analysis for discrimination among sand fly populations. Further development of molecular markers should resolve a possible existence of sibling species within Phlebotomus sergenti.  相似文献   
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