Specimens representing two new species of Guidus Ivanov, 2006 were collected from the Magellan skate (Bathyraja magellanica [Philippi]) in the Patagonian Continental Shelf of Argentina, Southwestern Atlantic Ocean. Guidus francoi sp. n. and Guidus magellanicus sp. n. differ from their congeners by a particular combination of features, including type of bothridia, worm length, number of testes, and distribution of vitelline follicles. Guidus francoi sp. n. is distinguished from G. magellanicus sp. n. by having fewer proglottids, fewer testes and a higher ratio between the cirrus sac length and the proglottid width. The microthrix pattern of species of Guidus from the Southwestern Atlantic is described, based on specimens of G. francoi sp. n., Guidus magellanicus sp. n., and newly collected specimens of Guidus argentinense Ivanov, 2006. These three species share the presence of wide aristate gladiate spinitriches on the proximal bothridial surface, narrow gladiate spinitriches on the bothridial rim, and filitriches on the distal bothridial surface. The diagnosis of Guidus is revised to include several features exhibited by the new species (i.e., presence of bothridial indentations and bothridial stalks, distribution of vitelline follicles, and eggs grouped in cocoons). The discovery of G. francoi sp. n. and G. magellanicus sp. n. from B. magellanica increases the number of species of Guidus collected from batoids in the Southwestern Atlantic from one to three. The specificity exhibited by the species herein described reinforces the tight association between rays in the genera Guidus and Bathyraja.
We analyzed the abundance, distribution and niche overlap of species (Pianka's Ojk index) in tenebrionid beetle communities inhabiting different biotopes in Tyrrhenian and Adriatic sand dunes. The rank abundance distribution of the different species has the form of a geometric series in both communities as predicted by the niche preemption hypothesis for communities in harsh environments. Mean niche overlap values did not deviate significantly from null expectations, which indicates random interspecific interactions. These results, coupled with evidence of species habitat preferences, led us to conclude that the community organization of tenebrionid species inhabiting coastal dunes is determined more by habitat preferences than interspecific competition., Simone Fattorini, Davide Bergamaschi, Cristina Mantoni, Alicia T. R. Acosta, Andrea Di Giulio., and Obsahuje bibliografii
The impacts of aquatic invasive species vary from the population to ecosystem level most strikingly through modifications to native communities, often leading to a decline in native species. A primary impact mechanism is competitive displacement of native by invasive species through resource partitioning. However, the trophic interactions between native and invasive species occupying the same habitat remain poorly understood, particularly at the early stages of invasion. This study used stable isotope analysis of two co-occurring populations of invasive topmouth gudgeon, Pseudorasbora parva and native Caucasian dwarf goby, Knipowitschia caucasica in a highly productive shallow lake to characterize overlap of potential trophic niches. The trophic niches of both species were divergent, with no overlap. Mixing models suggest some inter-specific dietary differences. The trophic niche of the Caucasian dwarf goby was slightly and non-significantly larger than that of topmouth gudgeon. These results suggest that when introduced outside of their natural range, topmouth gudgeon might integrate into new fish communities via the exploitation of resources that are underexploited by native fishes, which could also explain the high invasion success of the species.
Inducible NO synthase (NOS II) was proposed to play an important role in salt resistance of Dahl salt-resistant (SR/Jr) rats. Its chronic inhibition by specific inhibitors was accompanied by blood pressure (BP) elevation in animals subjected to high salt intake. The aim of our study was to evaluate 1) whether such inhibitors affect BP and/or its particular components (sympathetic tone and NO-dependent vasodilation) only under the conditions of high salt intake, and 2) whether similar BP effects are elicited after systemic or intracerebroventricular (icv) application of these inhibitors. Wistar rats fed Altromin diet (0.45 % NaCl) and SR/Jr rats fed either a low-salt (LS, 0.3 % NaCl) or a high-salt (HS, 4 % NaCl) diet were studied. Aminoguanidine (AMG) and 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) were used as NOS II inhibitors. BP and its responses to acute blockade of renin-angiotensin system (captopril), sympathetic nervous system (pentolinium) and NO synthase (L-NAME) were measured in conscious cannulated rats. There were no significant changes of BP or its components in either Wistar rats or SR/Jr rats subjected to chronic inhibition of NOS II by peroral aminoguanidine administration (50 mg/kg/day for 4 weeks). This was true for SR/Jr rats fed either LS or HS diets. Furthermore, we have studied BP effects of chronic icv administration of both NOS II inhibitors in SR/Jr rats fed HS diet, but we failed to find any BP changes elicited by such treatment. In conclusion, inducible NO synthase does not participate in the resistance of SR/Jr rats to hypertensive effects of excess salt intake.
Two japonica rice cultivars with different panicle trait index (PTI), HP917 (a high-PTI cultivar) and DP128 (a low-PTI cultivar) were used to investigate the effects of the nitrogen (N) rate and plant density on the grain distribution of secondary branches on the panicle axis, leaf photosynthetic characteristics, and grain yield by a split plot design. The main plots were assigned to four N rates (0, 140, 200, and 260 kg ha-1), and the subplots were assigned to two plant densities: (D20, 15 plants m-2; D10, 30 plants m-2). Results showed that the grain yield was increased by increasing N rate and plant density, reaching a peak at N200 with D10. Compared with N0 treatment, the PTIs of HP917 and DP128 increased with an increase in the N rate, respectively. The PTIs of HP917 and DP128 increased by 4% with increasing plant density from D20 to D10. The leaf capacity was significantly affected by N rate and plant density. The grain distribution characteristics of secondary branches on the panicle axis was closely related to yield. Correlation analysis showed the PTI was positively correlated with grain yield and net photosynthetic rate. These results suggested the improvement in PTI from 0.15 to 0.52 was beneficial to increase the grain yield, which might contribute to the increased grain number of secondary branches of the middle and bottom panicle.
Non-native species are known to escape their parasites following introduction into a new range, but they also often acquire local parasites as a function of time since establishment. We compared the parasite faunas of five non-native Ponto-Caspian gobies (Gobiidae) and local fish species (Perca fluviatilis, Gymnocephalus cernua, Gobio gobio) in three European river systems; the Rivers Rhine, Vistula and Morava, where Ponto-Caspian gobies were introduced 4-13 years prior to the study. Overall parasite species richness was considerably lower in non-native gobies compared to local fish species, and the same result was found at the component and infra-community levels. Both parasite abundance and diversity greatly varied among the regions, with the highest values found in the River Vistula (Wloclawski Reservoir), compared to a relatively impoverished parasite fauna in the River Morava (Danube basin). While only half of parasite species found in local hosts were acquired by non-native gobies, most of the parasites found in gobies were shared with local fish species related either phylogenetically (percids) or ecologically (benthic gudgeon), including the co-introduced monogenean Gyrodactylus proterorhini. As a result, similarity in parasite communities strongly reflected regional affiliation, while phylogenetic distances between fish host species did not play a significant role in parasite community composition. In accordance with other studies, all parasites acquired by gobies in their new range were generalists, all of them infecting fish at the larval/subadult stage, indicating the possible importance of gobies in the life cycle of euryxenous parasites. The absence of adult generalists, particularly ectoparasites with low host specificity, in non-native fish may reflect their generally low abundance in the environment, while an absence of adult endoparasitic generalists was probably related to other factors.
Arterial compliance is an important cardiovascular parameter characterizing mechanical and structural properties of arteries and significantly influencing ventricular-arterial coupling. Decreased arterial compliance is associated with several physiological states and pathological processes. Furthermore, arterial compliance is influenced by other cardiovascular parameters even at short time scales. Today, there are numerous noninvasive methods of estimation arterial compliance in vivo introducing some level of confusion about selection of the best method for particular application and measurement setting. In this review, the most common noninvasive methods of arterial compliance estimation are summarized, discussed and categorized. Finally, interpretation of estimated arterial compliance in the context of other possible confounders is discussed.
Climate change may facilitate shifts in the ranges and the spread of insect pests, but a warming climate may also affect herbivorous insects adversely if it disrupts the locally adapted synchrony between the phenology of insects and that of their host plant. The ability of a pest species to colonize new areas depends on its ability to adjust the timing of phenological events in its life cycle, particularly at high latitudes where there is marked seasonality in temperature and day length. Here we incubated eggs of three species of geometrid moth, Epirrita autumnata, Operophtera brumata and Erannis defoliaria from different geographical populations (E. autumnata and O. brumata from Northern Finland, E. autumnata and E. defoliaria from Southern Finland and all three species from Germany) in a climate chamber at a constant temperature to determine the relative importance of geographic origin in the timing of egg hatch measured in terms of cumulative temperature sums (degree days above 5°C, DD5); i.e. the relative importance of local adaptation versus phenotypic plasticity in the timing of egg hatch. In all three species, eggs from northern populations required a significantly lower temperature sum for hatching than eggs from southern populations, but the differences between them in temperature sum requirements varied considerably among species, with the differences being largest for the earliest hatching and northernmost species, E. autumnata, and smallest for the southern, late-hatching E. defoliaria. In addition, the difference in hatch timing between the E. autumnata eggs from Southern Finland and Germany was many times greater than the difference between the two Finnish populations of E. autumnata, despite the fact that the geographical distances between these populations is similar. We discuss how these differences in hatching time may be explained by the differences in hatch-budburst synchrony and its importance for different moth species and populations. We also briefly reflect on the significance of photoperiod, which is not affected by climate change. It is a controller that works parallel or in addition to temperature sum both for egg hatch in moths and bud burst of their host plants., Julia Fält-Nardmann, Tero Klemola, Mechthild Roth, Kai Ruohomäki, Kari Saikkonen., and Obsahuje bibliografii
Insects produce pigment and structural colours mainly for camouflage, signaling, physical protection or temperature regulation, and colour patterns can provide information about individual quality. Although the evolutionary function and nature of the variability in colouration are well known for many invertebrate taxa, there is little information on this topic for ants. We studied individual variation in the melanin-based colour traits of workers of the red wood ant, Formica rufa (Hymenoptera: Formicidae), from 20 colonies in Southern Finland and revealed the type of colouration in this species. First, using the threshold approach we distinguished between continuous and discrete variations. Furthermore, the analyses affirmed nine discrete morphs in terms of the colouration on the head and eight on the pronotum, while only continuous variation were found on the other body parts. Measuring the size of a particular colour pattern, the intensity of colour expression (degree of melanization) and statistical analyses allowed an assessment of the intra-individual variation in both discrete and continuous patterns. The results revealed substantial modularity in the above mentioned colouration traits. In workers of F. rufa there were individuals with a dark head and light coloured thorax and vice a versa. Size of the dark pigment colour patterns exhibited less modularity than the degree of melanization. Finally, the interrelation between colouration traits and individual body size revealed their size-dependent origin. Small individuals had relatively larger areas of colour on the head and thorax than big individuals. These results are likely to facilitate further taxonomical and ecological studies on red wood ants, as they show it is possible to assess colouration traits in ants. However, more studies are needed on the function of polymorphism and modular colouration in this group of ants., Oksana Skaldina, Jouni Sorvari., and Obsahuje bibliografii
The viviparous gyrodactylid genus Macrogyrodactylus Malmberg, 1957 is endemic to Africa, composed of nine species from hosts of four freshwater fish families, including catfishes (Siluriformes: Clariidae). Three species, Macrogyrodactylus clarii Gussev, 1961; M. congolensis (Prudhoe, 1957) and M. karibae Douëllou et Chishawa, 1995, are primarily known to parasitise the African sharptooth catfish Clarias gariepinus (Burchell) in various African countries. From November 2017 to September 2019, a total of 184 individuals of C. gariepinus were collected from selected localities in southern Africa and their skin, fins and gills were surveyed for monogeneans. Three species of Macrogyrodactylus (M. clarii, M. congolensis and M. karibae) were found parasitising C. gariepinus from five localities in South Africa and Zambia. Overall prevalence was 50% to 100% with intensities of up to 109 parasites per host individual. New locality records in southern Africa, morphological observations and additional molecular data on the complete Internal Transcriber Spacer (ITS-1-5.8S-ITS-2) regions of the rDNA gene for the three gyrodactylid species are presented in this study.