Effect of NaCl stress on dihaploid tobacco lines tolerant to Potato virus Y

Salinity is an important abiotic factor that limits plant growth and development. The influence of salt stress induced by sodium chloride on plant growth, proline content, level of lipid peroxidation and activities of antioxidative enzymes was studied in F1 hybrid DH10 and four dihaploid lines (207B, 238C, 239K, 244B) of tobacco (Nicotiana tabacum L.). Dihaploids were obtained from anther-derived haploids of hybrid DH10 and were previously proved to be tolerant to Potato virus Y (PVY). In our study, plants were grown in vitro and exposed to NaCl (100 and 200 mM) for 33 days. All dihaploids and hybrid DH10 showed reduced growth after NaCl treatment. They accumulated significant amounts of sodium and proline in response to salt stress as have already been observed in tobacco and other plant species. In tobacco exposed to NaCl the lipid peroxidation level did not increase and activities of superoxide dismutase (SOD), guaiacol peroxidase (POD), ascorbate peroxidase and catalase (CAT) mostly did not change significantly. The exception was line 239K where salt induced higher activities of SOD, CAT and POD. Two (238C and 244B) out of four dihaploids appeared more susceptible to salt stress as they showed weak growth in correlation with high proline and sodium content. Therefore, it seems that salt tolerance is not associated with tolerance to PVY. Variations in malondialdehyde and proline content as well as in enzymes activities observed among tobacco lines imply that dihaploids have different genetic properties which might result in different sensitivity to NaCl.     

Indirect cues in selecting a hunting site in a sit‐and‐wait predator

Sit‐and‐wait predators use relatively simple rules for their decisions to choose and leave a patch, such as using the direct presence of prey to select a hunting site. However, the direct presence of prey can only be used when there is a highly visited patch in the proximity of the predator. Therefore, it is plausible that sit‐and‐wait predators also exploit indirect cues of prey presence and, consequently, use associative learning to select a hunting site. The present study tests for the role of associative learning in a sit‐and‐wait predator species for which the ecology is well understood: Misumena vatia Clerck crab spiders. An ecologically relevant scenario is used by selecting flower colour as the conditioned stimulus and prey presence as the unconditioned stimulus. The results provide no evidence that M. vatia crab spiders use the association between flower colour and food presence for selecting a hunting site. After a training phase of being exposed to a colourful artificial flower highly visited by bees, spiders select a hunting site independently of its colour during the testing phase. Investigations of similar scope and ecological relevance are required with other sit‐and‐wait predators to identify the conditions promoting the use of associative learning for foraging site selection when animals face an unpredictable food supply.     

A new miocene lacustrine mollusc fauna of the Dinaride Lake System and its palaeobiogeographic,palaeoecologic and taxonomic implications

Abstract: The Dinaride Lake System, as one of the largest freshwater systems in the Neogene of Europe, is widely known for its exceptional mollusc fauna. During the Early and Middle Miocene, it displayed a major evolutionary hotspot resulting in a high level of endemicity. Despite advanced investigations in that region, comprehensive knowledge on the mollusc fauna of the Kupres basin is largely lacking. The herein presented results give insight into this outstandingly preserved fauna and are the base for a systematic revision of several supraspecific taxa among the Hydrobiidae. Because their phylogeny is poorly known, this study may serve as starting point for an overall systematic revision of this highly diverse family. Moreover, the faunal composition allows inferences on palaeobiogeography and hydrological connections within the Dinaride Lake System during the early Middle Miocene. About one‐third of the described taxa are restricted to the Kupres basin. The other taxa document faunistic relations to the coeval faunas of the Sinj, Drni? and D?epi basins. Phases of hydrological isolation, indicated by carbonate dominated lithology, coincide with a high frequency of sculptured morphologies within the gastropods. Phases of increased aridity led to high evaporation, a lowered lake level and enhanced carbonate production which seem to have promoted strongly calcified shells. The stratigraphic ranges of the species imply a depositional age of 15.5 ± 0.2 Ma (earliest Middle Miocene; Langhian). Among the Hydrobiidae Cyclothyrella gen. nov. and Pseudodianella gen. nov. are introduced as new genera. Bania obliquaecostata sp. nov., Melanopsis corici sp. nov., Nematurella vrabaci sp. nov., Prososthenia diaphoros sp. nov. and Prososthenia undocostata sp. nov. are described as new species. For the secondary homonym Melanopsis bittneri (Neumayr, 1880), the new name Melanopsis medinae nom. nov. is proposed.     

Effects of Tidal and Diel Cycles on Dugong Habitat Use

ABSTRACT Quantifying the factors influencing behaviors of aquatic mammalian grazers may enhance the generic understanding of grazer ecology. We investigated diel and tidal patterns in movements of the dugong (Dugong dugon) by Global Positioning System—tracking 12 animals in 5 inshore—intertidal and 3 offshore—subtidal habitats along the coast of Queensland, Australia. We examined effects of tide height and time of day on the dugong's distance from 1) the nearest coast, 2) water >3 m deep, 3) actual water depth (bathymetry + tide ht) experienced, and 4) distribution of the directions of movements. Both tidal and diel cycles influenced dugong movement. Tracked dugongs tended to be closer to shore at high tide than at low tide and closer to shore at night than during the day. Onshore movement was more prevalent on incoming tides and in the afternoon and evening. Offshore movement was more prevalent on outgoing tides and from midnight through the morning until midday. Tidal and diel variation in water depths used by the inshore—intertidal dugongs was small, but probably underestimated, hidden by a sampling bias in the telemetry equipment. Onshore movement at high tide allowed dugongs to exploit intertidal seagrass beds. Dugongs are closer to shore in afternoons and evenings than in mornings. This behavior may be related to the avoidance of predators or watercraft. Our findings can be used to predict spatial patterns of dugongs within areas of conservation management significance and to assess, avoid, and mitigate adverse effects of anthropogenic disturbance.     

Aquatain AMF efficacy on juvenile mosquito stages in control of Culex pipiens complex and Aedes albopictus

Aquatain^® mosquito formulation (AMF) is a silicone-based monomolecular film, which has recently been approved for use in the European Union. The physical mode of action based on lowering water surface tension prevents mosquito larvae/pupae respiration. Additionally, AMF disables gravid females from landing on the water surface and obstructs the natural oviposition process. Due to multistage effects on mosquitoes, AMF could be a product of choice for defined water body and container breeders such as Culex pipiens L. complex, principal vector of West Nile virus in Europe, and the invasive Aedes albopictus (Skuse) (both Diptera: Culicidae), vector of dengue and chikungunya viruses. The primary objectives of this study were to evaluate the efficacy of AMF, to determine the susceptibility of the immature forms of C. pipiens and A. albopictus, and the persistence/longevity of the product to suppress the eclosion of adults. AMF achieved high mortality rates of juvenile A. albopictus and C. pipiens under laboratory conditions. However, in the field C. pipiens larvae showed higher susceptibility to AMF than A. albopictus. Pupae of the two mosquito species were highly susceptible to the presence of AMF. When C. pipiens juveniles were exposed to AMF in the wild, effects lasted for 21 days in densely covered water bodies and 56 days in water recipients with less vegetation. In both breeding sites, natural habitat and artificial water recipient, the two mosquito species with high impact on public health in Europe could successfully be suppressed by application of AMF (1 ml m⁻²).     

PSYCHIATRY IN A BATTLE ZONE

The authors describe the arrival and treatment of 164 severe chronic psychiatric patients who were displaced from the Serbian army‐controlled Jakes psychiatric hospital and off‐loaded on the afternoon of 28th of May, 1992 at the gates of the Psychiatry Clinic in Tuzla. Through analysis of their incomplete medical records, which arrived with the patients in Tuzla, and analysis of their activities during and after the war, they found that 83 of the patients (50%) were males and 147 (89.6%) were admitted to the Psychiatry Clinic in Tuzla. Of the patients, 86 (58.5%) were found to be Serbs. The majority of them were incapable of independent living and required ongoing medical and social care. They were from all regions of Bosnia‐Herzegovina, 81.6% had schizophrenia and 70 (47.6%) were over 50 years of age. For its humanitarian work, its contribution to peace and for the maintenance of the multi‐ethnic Bosnia‐Herzegovina, the Psychiatry Clinic in Tuzla received the Golden Award for Peace from the International Legion of Humanists in May 1998.     

Too early? on the apparent conflict of astrobiology and cosmology

An interesting consequence of the modern cosmological paradigm is the spatial infinity of the universe. When coupled with naturalistic understanding of the origin of life and intelligence, which follows the basic tenets of astrobiology, and with some fairly incontroversial assumptions in the theory of observation selection effects, this infinity leads, as Ken Olum has recently shown, to a paradoxical conclusion. Olum's paradox is related, to the famous Fermi's paradox in astrobiology and “SETI” studies. We, hereby, present an evolutionary argument countering the apparent inconsistency, and show how, in the framework of a simplified model, deeper picture of the coupling between histories of intelligent/technological civilizations and astrophysical evolution of the Galaxy, can be achieved. This strategy has consequences of importance for both astrobiological studies and philosophy.     

Evolution of albinism in cave planthoppers by a convergent defect in the first step of melanin biosynthesis

Albinism, the reduction or loss of melanin pigment, is found in many diverse cave‐dwelling animals. The mechanisms responsible for loss of melanin pigment are poorly understood. In this study we use a melanogenic substrate assay to determine the position where melanin synthesis is blocked in independently evolved cave planthoppers from Hawaii and Croatia. In this assay, substrates of enzymes responsible for melanin biosynthesis are added to fixed specimens in vitro and their ability to rescue black melanin pigmentation is determined. L‐tyrosine, the first substrate in the pathway, did not produce melanin pigment, whereas L‐DOPA, the second substrate, restored black pigment. Substrates in combination with enzyme inhibitors were used to test the possibility of additional downstream defects in the pathway. The results showed that downstream reactions leading from L‐DOPA and dopamine to DOPA‐melanin and dopamine‐melanin, the two types of insect melanin, are functional. It is concluded that albinism is caused by a defect in the first step of the melanin synthesis pathway in cave‐adapted planthoppers from widely separated parts of the world. However, Western blots indicated that tyrosine hydroxylase (TH), the only enzyme shown to operate at the first step in insects, is present in Hawaiian cave planthoppers. Thus, an unknown factor(s) operating at this step may be important in the evolution of planthopper albinism. In the cavefish Astyanax mexicanus, a genetic defect has also been described at the first step of melanin synthesis suggesting convergent evolution of albinism in both cave‐adapted insects and teleosts.     

Do rivers and human-induced habitat fragmentation affect genetic diversity and population structure of the European ground squirrel at the edge of its Pannonian range?

The European ground squirrel (EGS) (Spermophilus citellus) populations of Vojvodina (Serbia) represent the southernmost part of its distribution in the Pannonian lowland. For species with low dispersal abilities a presence of even weak barriers can have significant influence on genetic structure among adjacent populations. We examined here the effects of habitat fragmentation and river barriers on the genetic structure of the EGS based on 12 microsatellite loci. Bayesian clustering methods were used as additions to classical population genetic approaches. We found that EGS populations in Vojvodina are highly fragmented, but their genetic variation is still higher than in peripheral populations in Central Europe. Populations in Vojvodina consistently grouped into three genetic clusters. The Danube, but not the Tisza River, represents an important barrier to gene flow. EGS populations in the studied area did not show the signs of recent genetic bottlenecks, as would be expected from observations of recent population declines. Conservation strategy should be focused on maintenance of remained suitable habitats and optimal population sizes.     

Subcellular localization of Nm23/NDPK A and B isoforms: a reflection of their biological function?

ABCG2 is a half-transporter initially described in multidrug-resistant cancer cells and lately identified as an important factor in the pharmacokinetics of its substrates. Q141K is by far the most intensively studied single nucleotide polymorphism of ABCG2 with potential clinical relevance. Here we used stably transfected HEK cells to study the Q141K polymorphism together with the deletion of amino acids 315–316, which were recently reported to coexist in two cancer cell lines (A549 and SK-OV-3). Functional studies confirmed our previous report that when normalized to surface expression, Q141K has impaired transport of mitoxantrone. This result was extended to include the ABCG2-specific substrate pheophorbide a. While we found no functional consequence of deleting amino acids 315 and 316, we did find that the deletion mutant is no longer recognized by the BXP-21 antibody. We conclude that amino acids 315 and 316 form part of the epitope for the BXP-21 antibody.