Rejskovití hmyzožravci (Soricidae) vydávají v nejrůznějších situacích mnoho typů hlasů. Dospělí jedinci se ozývají, pokud jsou v nebezpečí nebo se dostanou do potyčky s jiným jedincem svého druhu, během námluv a páření nebo při kontaktu s potomky. Také mláďata vydávají nejrůznější hlasy, jimiž se často snaží upozornit na své strádání nebo udržet kontakt s matkou a sourozenci. Přestože v poslední době přibývá publikací zabývajících se problematikou akustické komunikace rejskovitých, je to stále poměrně neprobádaná oblast. Mnohé otázky by mohly být zodpovězeny studiem bělozubky hnědé (Suncus murinus), která dobře prospívá i v péči člověka., Shrews (Soricidae) utter many types of vocalization in various situations. Adult individuals emit vocalizations when they are in danger or in a fight with conspecifics, during courtship and mating or when they keep contact with their offspring. Juveniles utter variable vocalizations mostly to prevent their discomfort and to keep contact with their mother and siblings. Although the number of publications has increased recently, acoustic communication among shrews still remains a quite unexplored field. Our knowledge might be significantly expanded by studying the Asian House Shrew (Suncus murinus), a species that can be successfully kept and bred in captivity., and Irena Schneiderová.
The effects of serosally added 5-hydroxytryptamine (5-HT, 100 μM) on the short circuit-current (Isc) across jejunum and ileum taken from fed, starved and undernourished (Gerbillus cheesmani) were investigated. The effects of the neurotoxin, tetrodotoxin (TTX, 10 μM) on the basal Isc as well as on the maximum increase in Isc induced by 5-HT were also studied. There were regional variations in the basal Isc as well as in the way by which the small intestine responds to 5-HT. The basal Isc was greater in jejunum than in ileum and such differences were TTX-sensitive. The maximum increase in Isc, which results from addition of 5-HT, was higher in jejunum than in ileum under all three feeding conditions. TTX reduced the maximum increase in Isc induced by 5-HT across stripped and intact intestine of the two regions in the three nutritional states. The 5-HT-induced Isc in the jejunum of both starved and undernourished gerbils and in the ileum of starved animals was the function of both submucosal and myenteric plexus. In jejunum and ileum taken from starved and undernourished gerbils the 5-HT-induced Isc was both chloride- and bicarbonate-dependent. Thus the results indicated that both starvation and undernourishment increase that response and such increases were TTX-sensitive and both chloride- and bicarbonate-dependent., F. Y. Al-Balool., and Obsahuje bibliografii a bibliografické odkazy
The effects of shoot girdling on stomatal conductance (gs), leaf photosynthesis (PN), concentrations of carbohydrates, nitrogen and chlorophyll (Chl) in leaves, areal leaf mass (ALM), the diameter and length of shoots, and bud abscission in pistachio were investigated. Girdling individual shoots at the base of the current year’s shoot (girdle I), separating inflorescent buds on the terminal current year’s shoot from the developing fruits on the previous year’s shoot, reduced inflorescent bud abscission by 70% in comparison to nongirdled controls. Girdle I significantly reduced concentrations of nitrogen in leaves but increased those of nonstructural carbohydrates particularly of starch. Shoot diameter increased by 13.1% and 26.4% at 33 and 81 days after girdling (DAG), respectively, compared to 1% and 3.4% in the control, respectively. Both the leaf dry mass/fresh mass ratio and ALM were increased significantly by girdle I from 12 DAG. The concentrations of Chl a, Chl b, Chl (a+b), as well as the ratio of Chl a/b, all decreased with girdle I. The greatest negative effect of girdle I was on gs and PN. PN was reduced by 55% of its initial value and was 44% less than in the control leaves at 10 DAG, and fell to approximately 30% that of the control from 21 DAG. In contrast, girdling at the base of one-year-old shoots (girdle II), thus not separating fruits from the inflorescent buds, did not significantly affect gs or PN. The effect of girdling on PN and the possible factors that are involved in the reduction of photosynthesis in pistachio are discussed., S. N. Vemmos, A. Papagiannopoulou, S. Coward., and Obsahuje bibliografii
Czech White-Nose Syndrome Team together with international collaborators discovered mechanisms of tolerance that protect Palearctic bats from white-nose syndrome (WNS), the disease that caused mass die-off in North America. The discovery raises hope for a better future of bats in North American ecosystems. White-nose syndrome (WNS) is caused by a generalist pathogen Pseudogymnoascus destructans with the worst possible characteristics of an infectious fungal agent. The generalist nature of the WNS fungus means that it can infect any bat hibernating in a contaminated cave or mine and, moreover, it may remain viable and virulent, waiting for its hosts until the next hibernation period. Harmless to humans, the WNS fungus kills hibernating North American bats in winter. However, loss of voracious insectivorous bats from agricultural ecosystems may result in economic costs required for increased pest control. Without mass die-offs of bats harbouring the WNS agent in Europe, the response to disease is an enigma. To study the survival crossroads, the Czech WNS Team focused on the relationship between pathogen quantity and disease under natural conditions. High disease prevalence together with high fungal loads in absence of bat population declines in Eurasia indicates disease tolerance mechanisms, where hosts limit harm inflicted by the pathogen but do not hinder its growth. The tolerance mechanisms revealed by the Czech WNS Team is a function of bat adaptation to the presence of the pathogen. and Natália Martínková.
Článek přináší přehled současných znalostí o fylogenezi mnohobuněčných živočichů, tak jak vycházejí ze současného fylogenomického výzkumu. Zvláštní pozornost je věnována skupinám s konfliktním postavením (Ctenophora, Xenacoelomorpha, Bryozoa) a skupinám, o jejichž postavení dosud nevíme téměř nic (Dendrogramma, Dicyemida, Orthonectida)., We present an overview of current knowledge on the phylogeny of multicellular animals, based on current phylogenomic research. This overview pays special attention to groups with uncertain positions (Ctenophora, Xenacoelomorpha, Bryozoa) and groups whose position is still largely unknown (Dendrogramma, Dicyemida, Orthonectida)., and Jan Zrzavý.
a1_Attention should be paid to ozone (O3) sensitivity of greening plant since ground-level O3 concentrations are increasing especially in urban and suburban area. We studied the ecophysiological responses to elevated O3 of four shrub species [Euonymus bungeanus Maxim. (EB), Photinia × fraseri (PF), Chionanthus retusus Lindl. & Paxt. (CR) and Cornus alba L. (CA)], which are often used for garden greening in China. Saplings of those species were exposed to high O3 concentration (70 nmol mol-1, 7 h d-1 for 65 d) in open-top growth chambers. Responses to O3 were assessed by gas exchanges, chlorophyll (Chl) fluorescence and dry mass. We found that elevated O3 significantly decreased lightsaturated net photosynthetic rate (PNsat), transpiration rate (E) and stomatal conductance (gs). The ratio of intercellular CO2 to ambient CO2 concentration (Ci/Ca) did not reduce under O3 fumigation which suggested that the O3-induced depressions of P Nsat under O3 fumigation were probably due to limitation of mesophyll processes rather than stomatal limitation. High O3 exposure also significantly depressed the maximum efficiency of photosystem II (PSII) photochemistry in the dark-adapted state (Fv/Fm) which meant the O3-induced photoinhibition. Both root dry mass and root/shoot ratios were significantly decreased under ozone fumigation, but the total mass was unchanged. The responses of gas exchange such as PNsat in these four shrubs to O3 exposure were species-specific. Highest loss of PNsat was observed in EB (-49.6%), while the CR had the lowest loss (-36.5%). Moreover, the O3-exposed CR showed similar gs as CF, reflecting that its O3 flux might be unchanged under elevated O3 environment. Ozone drastically decreased actual quantum yield of PSII (ΦPSII) and electron transport rate (ETR) in EB while increased ΦPSII and ETR in CR., a2_Furthermore, the relative losses in P Nsat positively correlated with the relative decreases in ΦPSII and ETR which indicated that the impairment of photosynthesis was probably affected by the light reaction process. The light reaction of EB was impaired most seriously but that of CR was not damaged. All results indicated that EB was probably the most sensitive shrub species to O3 while CR the most tolerant one. Therefore, CR might be an ideal choice for greening in ozone-polluted areas., L. Zhang ... [et al.]., and Obsahuje bibliografii
a1_Low light availability under a forest canopy often limits plant growth; however, sudden increase in light intensity may induce photoinhibition of photosynthesis. The aim of this study was to evaluate the ecophysiological changes that occur in potted plants of Minquartia guianensis and Swietenia macrophylla during the acclimation process to full sunlight. We used six full-sun independent acclimation periods (30, 60, 90, 120, 150, and 180 days) and a control kept in the shade. Shading was obtained by placing plants under the canopy of a small forest. The Fv/Fm ratio, net photosynthetic rate (PN), the maximum carboxylation velocity of Rubisco (Vcmax), maximum electron transport rate (Jmax), specific leaf area (SLA), and growth were assessed at the end of each of the six acclimation periods. Plant exposure to full sunlight caused a sudden decrease in the Fv/Fm ratio (photoinhibition) particularly in Minquartia. Photooxidation (necrotic patches) of the leaf tissue was observed in upper leaves of Minquartia. The higher PN values were observed in Swietenia under full sun, about 12 μmol(CO2) m-2 s-1. Vcmax25 values were higher after 90 days of acclimation, about 14 μmol(CO2) m-2 s-1 for Minquartia, and 35 μmol(CO2) m-2 s-1 for Swietenia. At the end of a 180-d acclimation period Jmax25 was 35 μmol(electron) m-2 s-1 for Minquartia and 60 μmol(electron) m-2 s-1 for Swietenia. SLA was higher in Swietenia than in Minquartia. In Minquartia, monthly rate of leaf production per plant (MRLP) was positive (0.22 leaf month-1) after four months in the open. Whereas, in Swietenia MRLP was positive (0.56 leaf month-1) after an acclimation period of two months. After six months in the open, height growth rates were 3.5 and 28 mm month-1 for Minquartia and Swietenia, respectively., a2_The greater acclimation capacity of Swietenia was associated to an enhanced photosynthetic plasticity under full sun. In Minquartia, transition to full-sun conditions and lack of physiological adjustment resulted in severe photoinhibition and loss of leaves., G. F. C. Azevedo, R. A. Marenco., and Obsahuje bibliografii