Morphofunctional changes of the digestive gland in the bivalve mollusk Crenomytilus grayanus (Dunker, 1853) in normal conditions and after parasitic invasion by trematodes

Specifics of the digestive cycle were studied in normal individuals of Gray’s mussel Crenomytilus grayanus and in those infested by trematodes from an unpolluted area of the sublittoral zone of Peter the Great Bay in May (during the day), June, July, and August. Four types of tubules corresponding to four phases of the digestive cycle were identified, and three varieties of destructing tubules were distinguished. It was shown that normally phases of absorption and digestion prevailed in the digestive gland. The portion of absorptive tubules (type II) was 95% in spring and 79% in summer. The total portion of destructing and restoring tubules (types III and IV) did not exceed 10% in spring and 20% in summer, and portion of tubules at the initial condition (type I) was 4% in spring and 2% in summer. During the day, insignificant variations in the ratio of different type tubules were recorded. It was revealed that, normally, granulocytomes were formed during utilization of necrotic tubules. Parasitic invasion of trematodes entailed swelling of the gland and a change in the proportion of tubules: the number of absorptive tubules decreased to 20%, the number of destructing and restoring tubules increased up to 60% and 12%, respectively.     

Cretophengodidae,a new Cretaceous beetle family,sheds light on the evolution of bioluminescence

Bioluminescent beetles of the superfamily Elateroidea (fireflies, fire beetles, glow-worms) are the most speciose group of terrestrial light-producing animals. The evolution of bioluminescence in elateroids is associated with unusual morphological modifications, such as soft-bodiedness and neoteny, but the fragmentary nature of the fossil record discloses little about the origin of these adaptations. We report the discovery of a new bioluminescent elateroid beetle family from the mid-Cretaceous of northern Myanmar (ca 99 Ma), Cretophengodidae fam. nov. Cretophengodes azari gen. et sp. nov. belongs to the bioluminescent lampyroid clade, and would appear to represent a transitional fossil linking the soft-bodied Phengodidae + Rhagophthalmidae clade and hard-bodied elateroids. The fossil male possesses a light organ on the abdomen which presumably served a defensive function, documenting a Cretaceous radiation of bioluminescent beetles coinciding with the diversification of major insectivore groups such as frogs and stem-group birds. The discovery adds a key branch to the elateroid tree of life and sheds light on the evolution of soft-bodiedness and the historical biogeography of elateroid beetles.     

Response of Carnian Pluvial Episode evidenced by organic carbon isotopic excursions from western Hubei,South China

We here report a high-resolution organic C-isotope record from terrestrial–marine transitional sediments of the Badong Formation in the Luojiagou section, Zigui Basin of Hubei Province, South China. Our organic carbon isotope (δ¹³C_org) profile, ranging from -21.2‰ to -26.2‰, shows four negative carbon-isotope shifts. We suggest that the sharpest negative carbon isotope excursion in the upper portion of the Badong Formation marks the main phase of the Carnian Pluvial Episode (CPE) in the basin, likely correlated with those in other depositional records of this time. The occurrence of the CPE in the Badong Formation would imply that the stratigraphic coverage of the Badong Formation might be prolonged to incorporate (at least part of) the Late Triassic Carnian stage. This result provides a potential case for understanding the CPE in continental–marine environments in the eastern Tethys realm, and is significant for exploring the palaeoclimate variation across the Late Triassic.     

Analysis of temporal variability in the concentrations of some elements in the terrestrial moss Pseudoscleropodium purum

The uptake of contaminants by moss is a complex process that depends on the nature and characteristics of the contaminants and on the physicochemical and biological processes that affect the moss. All of these factors in turn depend on environmental variables that may vary within a short time. It can therefore be assumed that the uptake of elements varies in such short periods that it is very difficult to obtain temporally representative results in biomonitoring studies with terrestrial moss. In order to investigate the temporal variability and the implications that it may have on the interpretation of the results obtained in this type of study, the tissue concentrations of 12 elements were determined in samples of the moss Pseudoscleropodium purum collected from two sampling sites in Galicia (NW Spain), during a long term survey with a high frequency of sampling. The results showed that the concentrations of the elements in the moss varied greatly within very short periods, and that the error associated with the temporal variability in the results was high. In accordance with these findings, and taking into account that the technique enabled contaminated and uncontaminated sites to be distinguished, we recommend that the results of biomonitoring studies should be regarded as qualitative or semiqualitative, rather than attempting to provide absolute data, which may not be temporally representative, and may have a high degree of uncertainty associated with them.     

Method of color measurements of the elements of color in gastropods shell

The method of the accurate determination of the shell color of gastropods has been studied with the example of the gastropod Littorina obtusata. The suggested method is based on using the system of MKO RGB color coordinates and makes it possible to conduct measurements of both color as a whole and the color of the individual elements of the shell picture.     

Extreme climatic events and host–pathogen interactions: The impact of the 1976 drought in the UK

Intense, long droughts have increased in occurrence since the 1970s and have been linked with global climate change. Extreme climate alters the risk of pathogen infections and diseases in both animals and plants, although little is known about the impact of any single event on host–pathogen dynamics in a wide range of species. Evaluating past climatic events can provide valuable information on complex interactions that occur between hosts, pathogens, and the environment, thereby paving the way for predictive models and ultimately early and efficient response to disease threats. The present study reviews the substantial impact of the 1976 UK drought on climate-driven host–pathogen associations. This 16-month drought had a devastating effect on flora and fauna and is considered a benchmark for dry conditions in this country. Changes to the occurrence of infections in farmed and wild animals and plants are presented in terrestrial, freshwater, and marine ecosystems and the implications for pathogen transmission under extreme climate conditions are assessed.     

A predatory land snail invades central-western Argentina

The pulmonate land snail, Rumina decollata, is a highly invasive gastropod adapted to arid conditions, and native from the Mediterranean area. It was recorded for the first time in Argentina in 1988, in the northeastern Pampas of the Buenos Aires Province, a region characterized by a humid mesothermal climate with no water deficit. In the present contribution, we report the finding of populations of this species in the semiarid region of La Pampa and Mendoza provinces in central-western Argentina. The present findings extend the invasive distributional range of R. decollata westwards through more than 1000 km from the site where it was detected in 1988. Although no damages to agricultural areas have been reported to the moment in Argentina, the presence of R. decollata in semiarid areas warns us about its potential as an important plague in the future.