A highly permeable species boundary between two anadromous fishes

Meristic identification, mitochondrial DNA and a suite of microsatellite markers were employed to estimate the incidence of hybridization in wild populations of anadromous Allis shad Alosa alosa and twaite shad Alosa fallax in southern Irish riverine and estuarine waters. It was shown that 16% of the fishes examined were misclassified using meristic count of gill rakers. Next, a significant proportion of fishes that were robustly assigned to a species using nuclear markers were shown to possess the mtDNA of the other. The genomes of A. alosa and A. fallax in Ireland are extensively introgressed, which suggests a complex history of hybridization between these species, which can only partially be explained by recent man-made habitat changes.     

Pathogenicity of Pochonia species on eggs of Meloidogyne javanica

Among fungi, species of the genus Pochonia Batista & O.M. Fonseca are considered as promising biological control agents with high potential to reduce root-knot nematode (RKN) and nematode populations. In this research we investigated Fars province of Iran for the presence of Pochonia spp., compared pathogenicity of different Pochonia species on eggs of RKN in vitro, and selected the best isolates for further studies. During 2004-2006, 128 soil samples of fields infested with cyst nematodes and 18 soil samples infested with RKN were collected from Fars province of Iran. In vitro pathogenicity tests were carried out on 36 isolates of Pochonia spp. obtained from CBS and IRAN culture collections. The seven best isolates of this experiment were selected for greenhouse test and their ability in controlling RKN was examined in natural soil. In greenhouse test fresh weight of plant’s tops and roots, gall index, nematode multiplication, second-stage juveniles’ population in soil, reproduction rate (P_f/P_i), proportion of infected eggs, control efficacy, root colonization and soil colony forming units were determined. In vitro pathogenicity of Pochonia on RKN eggs varied between 39% and 95% eggs infected. In greenhouse experiment, three isolates are promising for control of RKN and selected isolates are subjected to more extensive testing to determine their effectiveness in a range of conditions before being developed as commercial biological control agents.     

Molecular identification of Ehrlichia species and 'Candidatus Neoehrlichia mikurensis' from ticks and wild rodents in Shizuoka and Nagano Prefectures, Japan

A total of 293 ticks and 111 wild rodents that were collected in Shizuoka and Nagano Prefectures, Japan, were examined for infection of Ehrlichia species and 'Candidatus Neoehrlichia mikurensis.' The 16S rDNA or the omp-1 gene of these bacterial DNAs were detected from the spleens of tick-inoculated mice (5 positive/total 29 mice) or from the spleens of wild rodents (25 positive/total 111 rodents) by PCR amplifi-cation. Sequencing of the 16S rDNA revealed Ehrlichia spp. from the 5 tick-inoculated mice and 8 wild rodents, and 'Candidatus N. mikurensis' from 17 wild rodents. The data suggest the presence of additional genetic variants, and potential vectors and/or reservoirs for these bacteria in central Japan.     

Reproductive modes of three Ligularia weeds (Asteraceae) in grasslands in Qinghai-Tibet Plateau and their implications for grassland management

Ligularia virgaurea, L. sagitta and L. przewalskii are noxious weeds that are widely distributed in psychro-grasslands in the east of Qinghai-Tibet Plateau of China. However, little is known about reproductive modes and genetic diversity in the populations of L. virgaurea and L. sagitta under different environmental conditions, although such information is available for L. przewalskii. In this study, two experiments were conducted to examine the ex situ clonal growth of these weeds, and to determine the effects of reproductive modes on the diversity of their populations, using random amplified polymorphic DNA (RAPD) analysis. Transplanted seedlings of L. sagitta and L. virgaurea showed considerable clonal growth by forming rhizomes and ramets. The RAPD analysis showed that all individuals collected from natural populations were genetically different, indicating that no individuals originated from clonal growth. It is concluded that L. virgaurea and L. sagitta have the capacity for clonal growth, but the expression of their clonality is constrained by their growing conditions in natural grasslands. Sexual reproduction plays the major role in their population diversity in natural habitats, which requires that the control measures for these weeds should be targeted at the sexually reproducing populations.     

The use of probiotics in shrimp aquaculture

Shrimp aquaculture, as well as other industries, constantly requires new techniques in order to increase production yield. Modern technologies and other sciences such as biotechnology and microbiology are important tools that could lead to a higher quality and greater quantity of products. Feeding and new practices in farming usually play an important role in aquaculture, and the addition of various additives to a balanced feed formula to achieve better growth is a common practice of many fish and shrimp feed manufacturers and farmers. Probiotics, as 'bio-friendly agents' such as lactic acid bacteria and Bacillus spp., can be introduced into the culture environment to control and compete with pathogenic bacteria as well as to promote the growth of the cultured organisms. In addition, probiotics are nonpathogenic and nontoxic microorganisms without undesirable side-effects when administered to aquatic organisms. These strains of bacteria have many other positive effects, which are described in this article.     

Antimicrobial activity in cultures of endophytic fungi isolated from Garcinia species

The aim of the present study was to screen for antimicrobial activity in endophytic fungi isolated from surface sterilized leaves and branches of five Garcinia plants, G. atroviridis, G. dulcis, G. mangostana, G. nigrolineata and G. scortechinii, found in southern Thailand. Fermentation broths from 377 isolated fungi were tested for antimicrobial activity by the agar diffusion method. Minimum inhibitory concentrations (MICs) were obtained for crude ethyl acetate extracts. Seventy isolates (18.6%) displayed antimicrobial activity against at least one pathogenic microorganism, such as Staphylococcus aureus, a clinical isolate of methicillin-resistant S. aureus, Candida albicans and Cryptococcus neoformans. The results revealed that 6-10%, 1-2% and 18% of the crude ethyl acetate extracts inhibited both strains of S. aureus (MIC 32-512 microg mL(-1)), Ca. albicans and Cr. neoformans (MIC 64-200 microg mL(-1)), and Microsporum gypseum (MIC 2-64 microg mL(-1)), respectively. Isolates D15 and M76 displayed the strongest antibacterial activity against both strains of S. aureus. Isolates M76 and N24 displayed strong antifungal activity against M. gypseum. Fungal molecular identification based on internal transcribed spacer rRNA gene sequence analysis demonstrated that isolates D15 (DQ480353), M76 (DQ480360) and N24 (DQ480361) represented Phomopsis sp., Botryosphaeria sp. and an unidentified fungal endophyte, respectively. These results indicate that some endophytic fungi from Garcinia plants are a potential source of antimicrobial agents.     

Dendrochronology in suboptimal conditions: tree rings from medieval oak from Flanders (Belgium) as dating tools and archives of past forest management

Throughout the Middle Ages forests in Flanders (northern Belgium) experienced a dramatic human influence. Forests were logged for wood supply and converted to arable land. The structure of the remaining forests was altered. This, combined with the tempering influence of the Atlantic climate, results in conditions that are suboptimal for dendrochronological research. Tree-ring series of Quercus robur and Q. petraea of timber from medieval archaeological sites are often short, show abrupt growth-rate variations and are complacent. The question arises whether tree-ring series of this type are potential records of past management and whether they could constitute the basis of a reference chronology for archaeological dating. During six archaeological excavations in and around the medieval town of Ypres, cross-sections were collected. The tree-ring series could be dated back to the 12th–14th centuries, using reference chronologies from surrounding regions. The growth pattern of the short sequences displays a high similarity to tree-ring series from modern coppice. For the first time, it has been confirmed that dendrochronological analysis in Flanders is possible and can provide valuable information on medieval forest use and structure.     

Antifungal effects of the volatile oils from Allium plants against Trichophyton species and synergism of the oils with ketoconazole

In an attempt to develop stable and safe antifungal agents from natural products (daily foodstuffs in particular), the activities of essential oils from Allium sativum for. pekinense, A. cepa, and A. fistulosum against three Trichophyton species responsible for severe mycoses in humans were investigated and compared with activity of allicin in this study. The fungistatic activities of Allium oils were evaluated by the broth dilution method and disk diffusion assay. The combined effects of Allium oils with ketoconazole were tested by the checkerboard titer test. Among the tested oils, A. sativum for. pekinense oil exhibited the strongest inhibition of growth of T. rubrum, T. erinacei, and T. soudanense with MICs (minimum inhibiting concentrations) of 64microg/ml, while the activities of A. cepa and A. fistulosum were relatively mild. The inhibiting activities of the oils on Sabouraud agar plates were dose dependent against Trichophyton species. Additionally, these oils showed significant synergistic antifungal activity when combined with ketoconazole in the checkerboard titer test and disk diffusion test.     

Exclusive frugivory and seed dispersal of Rhamnus alaternus in the bird breeding season

We studied avian frugivory and seed dispersal in a dioecious shrub, Rhamnus alaternus, focusing on the quantitative and qualitative components of effectiveness. The study took place at three locations in the northeast of the Iberian Peninsula, and examined bird behaviour, intensity of feeding, and the consequences for seedling emergence. The coincidence between the bird breeding season and fruit ripening of R. alaternus in the absence of other ripe fruit, generates a monospecific interaction. The extant frugivorous species were mainly legitimate seed dispersers and their abundance was low. Sylvia melanocephala and S. undata were the most important at one site whereas S. atricapilla, Erithacus rubecula and Turdus merula predominated at the other two sites. Fruit handling took place directly on the branches. Bird species used microhabitats differently as first post-feeding perch, which usually was a short distance away. The low density of frugivorous birds in all localities, among others factors, resulted in satiation of the disperser community and many mature fruits unconsumed. Both adults and juveniles feed upon the plants and their foraging patterns are similar. Adults of S. melanocephala were observed to feed fruit to nestlings and consequently a second phase of dispersal potentially arises from the transport of fecal sacs. Pulp removal and passage through the digestive tract increased the probability of seedling emergence. This plant-dispersal interaction has important consequences, both positive and negative for the plant. Positively, the fruiting of R. alaternus at a time when other ripe fruits are not available avoids interspecific competition for seed dispersers. In addition, a low density of seed rain may reduce intraspecific competition. Negatively, the low density and small size of the breeding frugivorous bird community limit fruit handling and removal away from the parent plants, while the territorial behaviour of birds at that time of the year reduces the potential distances of seed dispersal.     

Genetic stability of three economically important micropropagated banana (Musa spp.) cultivars of lower Indo-Gangetic plains, as assessed by RAPD and ISSR markers

An efficient micropropagation protocol produced large number of plants of the three elite banana (Musa spp.) cultivars Robusta (AAA), Giant Governor (AAA) and Martaman (AAB) from shoot tip meristem. The genetic relationships and fidelity among the cultivars and micropropagated plants as assessed by random amplified polymorphic DNA (RAPD) and inter-simple sequence repeat (ISSR) markers, revealed three somaclonal variants from Robusta and three from Giant Governor. A total of 5330 RAPD and 2741 ISSR fragments were generated with 21 RAPD and 12 ISSR primers in micropropagated plants. The percentage of polymorphic loci by RAPD and ISSR were found to be 1.75, 5.08 in Robusta and 0.83, 5.0 in Giant Governor respectively. Among the two marker systems used, ISSR fingerprinting detected more polymorphism than RAPD in Robusta and Giant Governor with most of the primers showing similar fingerprinting profile, whereas Martaman revealed complete genetic stability.