Predicted effects of increasing salinity on the crustacean zooplankton community of Pyramid Lake,Nevada

Since 1933 the salinity of Pyramid Lake, Nevada, U.S.A., has increased 32% to nearly 5.5‰. We tested the hypothesis that further increases of 1.5 to 2 times (1.5× to 2×) its present salinity would significantly reduce species richness and alter population structures of the existing crustacean zooplankton community. Three strategies were applied: in addition to monitoring zooplankton in semicontrolled indoor microcosms at 1×, 1.5× and 2× and conducting range-finding, acute, and chronic salinity bioassays, the present zooplankton community of Walker Lake (2×) was compared with that existing in Pyramid Lake (1×). Ceriodaphnia quadrangula and Diaphanosoma leuchtenbergianum, both collected from Pyramid Lake, were lacking in Walker Lake. Populations of Cyclops vernalis were significantly lower and those of Diaptomus sicilis and Moina hutchinsoni were significantly higher in Walker Lake than in Pyramid Lake. Densities of Ceriodaphnia and Cyclops were low in microcosms at salinities > 1×. Diaphanosoma could not be maintained in microcosms, regardless of salinity. Numbers of Diaptomus and Moina in microcosms were proportional to salinity level. Short-term LC50 salinities (‰) were as follows: Diaphanosoma, 6.5; Ceriodaphnia, 7.1; Diaptomus, 13.3; Cyclops, 14.8; and Moina, 17.8. Multiple-generation, chronic bioassays were run only on Cyclops and Diaptomus. Three generations of Cyclops were produced at salinities of 4.0 to 8.5‰, but not at 9.8‰ or higher. Diaptomus was unable to complete three generations at salinities ?9.6‰. We speculate that high salinity in Walker Lake may indirectly benefit Diaptomus by negatively affecting predatory Cyclops, and benefit Moina by causing extinction of competing salinity-intolerant Diaphanosoma and Ceriodaphnia. Except for the response of Diaptomus, results from bioassays were in general agreement with results from microcosms and with field data. Untested predator-prey interactions could be responsible for the apparent discrepancy.     

Monoculture,polyculture, and polyvariety in tropical forest Swidden cultivation

A number of researchers have suggested that polyculture is characteristic of native tropical forest swiddens and have adduced theory from community ecology to account for its adaptiveness. Ye'kwana and Yanomamö swidden cultivation is examined, and it is shown that polyculture is not practiced to any significant degree. Instead, the concept of polyvariety is introduced along with a number of other cultivation practices that more simply account for the adaptiveness of Ye'kwana and Yanomamö gardening. In addition, comparative data from other parts of the tropical world indicate that polyculture is no more common than monoculture and recent advances in ecological research indicate that the diversity-stability hypothesis that underpins adaptive arguments of polyculture is in need of drastic revision.     

On the carrying behaviour of basic South American primates

InCallithrix, Saguinus, Aotus, andCallicebus other group members than the mother participate in infant care. Differences among these species are obvious in respect to the time of being off any caregiver, and in respect to the carrying position (Aotus andCallicebus). Alloparental care, a basic behaviour pattern in these species, has evolved from the parking behaviour of the prosimians. The infants are «parked» at other group members.     

Molecular charcterization of tatD DNAse gene from Ralstonia paucula RA4T soil bacterium

Ralstonia paucula strain RA4^T, a gram negative, non-spore forming, motile bacterium having positive catalase and oxidase test, was isolated from surface soil. Twin arginine translocation protein type D (TatD) is shown to be located in cytoplasm and exhibits magnesium-dependent DNase. A tatD DNase gene was isolated and cloned from Ralstonia paucula RA4^T genome. Nucleotide sequence analysis of the gene revealed 813 nucleotides encoding a protein of 270 amino acid residues. The tatD gene showed a high similarity to homolog gene from Ralstonia pickettii strain 12D. The deduced polypeptide sequence of TatD DNase from R. paucula RA4^T had a typical catalytic site, HHPLDEHRHDP, and its calculated molecular mass and predicted isoelectric point were 29616 Da and 5.33, respectively. The deduced amino acid sequence showed a high degree of similarity to TatD DNase isoforms from Ralstonia genus and other sources. Predicted three-dimensional structure of TatD confirmed the presence of active site and theoretical function as DNase.     

Molecular evidence to reconcile taxonomic instability in mahseer species (Pisces: Cyprinidae) of India

The mahseers are an important group of fishes endemic to Asia with most species considered threatened. Conservation plans to save declining wild populations are hindered by unstable taxonomy, and detailed systematic review could form a solid platform for future management and conservation. D-loop and cytochrome c oxidase I (COI) mtDNA sequences were examined in nine mahseer species of Tor, Neolissochilus, and Naziritor. Pseudogenes amplified in a portion of the species limited the utility of the D-loop region. ABGD analysis, NJ, ML, and MP methods and genetic distance (TrN?+?I?+?G) using COI data revealed concordant species delimiting patterns. The three genera were monophyletic, separated as distinct clades (TrN?+?I?+?G 0.064 to 0.106), and Naziritor was flagged as a separate genus, distinct from Puntius (TrN?+?I?+?G 0.196). Out of seven nominal species known for Tor cogeners from India, only five were recovered with mtDNA data (TrN?+?I?+?G 0.000 to 0.037) and two species could not be distinguished with the molecular data set employed. Tor mosal, synonymized as Tor putitora, was rediscovered as a distinct species (TrN?+?I?+?G 0.031) based on its type locality. Tor mussulah was confirmed as a separate species (TrN?+?I?+?G 0.019 to 0.026). Two valid species, Tor macrolepis and T. mosal mahanadicus, were not distinct from T. putitora (TrN?+?I?+?G 0.00). The high divergence with mtDNA data failed to validate T. mosal mahanadicus as a subspecies of T. mosal (TrN?+?I?+?G 0.031). Morphological outliers discovered within the distribution range of Tor tor (TrN?+?I?+?G 0.022 to 0.025) shared the same lineage with T. putitora (TrN?+?I?+?G 0.002 to 0.005), indicating a new extended distribution of the Himalayan mahseer T. putitora in the rivers of the Indian central plateau. The findings indicate the need for integrating molecular and morphological tools for taxonomic revision of the Tor and Naziritor genera, so that taxa are precisely defined for accurate in situ and ex situ conservation decisions.     

Influence of bovine lactoferrin on the growth of selected probiotic bacteria under aerobic conditions

Bovine lactoferrin (bLf) is a natural glycoprotein, and it shows broad-spectrum antimicrobial activity. However, reports on the influences of bLf on probiotic bacteria have been mixed. We examined the effects of apo-bLf (between 0.25 and 128 mg/mL) on both aerobic and anaerobic cultures of probiotics. We found that bLf had similar effects on the growth of probiotics under aerobic or anaerobic conditions, and that it actively and significantly (at concentrations of >0.25 mg/mL) retarded the growth rate of Bifidobacterium bifidum (ATCC 29521), B. longum (ATCC 15707), B. lactis (BCRC 17394), B. infantis (ATCC 15697), Lactobacillus reuteri (ATCC 23272), L. rhamnosus (ATCC 53103), and L. coryniformis (ATCC 25602) in a dose-dependent manner. Otherwise, minimal inhibitory concentrations (MICs) were 128 or >128 mg/mL against B. bifidum, B. longum, B. lactis, L. reuteri, and L. rhamnosus (ATCC 53103). With regard to MICs, bLf showed at least four-fold lower inhibitory effect on probiotics than on pathogens. Intriguingly, bLf (>0.25 mg/mL) significantly enhanced the growth of Rhamnosus (ATCC 7469) and L. acidophilus (BCRC 14065) by approximately 40–200 %, during their late periods of growth. Supernatants produced from aerobic but not anaerobic cultures of L. acidophilus reduced the growth of Escherichia coli by about 20 %. Thus, bLf displayed a dose-dependent inhibitory effect on the growth of most probiotic strains under either aerobic or anaerobic conditions. An antibacterial supernatant prepared from the aerobic cultures may have significant practical use.     

Occurrence of Phytophthora plurivora and other Phytophthora species in oak forests of southern Poland and their association with site conditions and the health status of trees

Phytophthora plurivora and other Phytophthora species are known to be serious pathogens of forest trees. Little is known, however, about the presence of P. plurivora in Polish oak forests and their role in oak decline. The aims of this study were to identify P. plurivora in healthy and declining Quercus robur stands in southern Poland and to demonstrate the relationship between different site factors and the occurrence of P. plurivora. In addition, the virulence of P. plurivora and other Phytophthora species was evaluated through inoculations using 2-year-old oak seedlings. Rhizosphere soil was investigated from 39 oak stands representing different healthy tree statuses. The morphology and DNA sequences of the internal transcribed spacer regions (ITS) of the ribosomal DNA and the mitochondrial cox1 gene were used for identifications. P. plurivora, an oak fine root pathogen, was isolated from rhizosphere soil samples in 6 out of 39 stands. Additionally, Phytophthora cambivora, Phytophthora polonica and Phytophthora rosacearum-like were also obtained from several stands. The results showed a significant association between the presence of P. plurivora and the health status of oak trees. Similar relationships were also observed for all identified Phytophthora species. In addition, there was evidence for a connection between the presence of all identified Phytophthora species and some site conditions. Phytophthora spp. occurred more frequently in declining stands and in silt loam and sandy loam soils with pH?≥?3.66. P. plurivora and P. cambivora were the only species capable of killing whole plants, producing extensive necrosis on seedling stems.     

Crystal structure of tRNA m1A58 methyltransferase TrmI from Aquifex aeolicus in complex with S-adenosyl-l-methionine

The N ¹-methyladenosine residue at position 58 of tRNA is found in the three domains of life, and contributes to the stability of the three-dimensional L-shaped tRNA structure. In thermophilic bacteria, this modification is important for thermal adaptation, and is catalyzed by the tRNA m¹A58 methyltransferase TrmI, using S-adenosyl-l-methionine (AdoMet) as the methyl donor. We present the 2.2 Å crystal structure of TrmI from the extremely thermophilic bacterium Aquifex aeolicus, in complex with AdoMet. There are four molecules per asymmetric unit, and they form a tetramer. Based on a comparison of the AdoMet binding mode of A. aeolicus TrmI to those of the Thermus thermophilus and Pyrococcus abyssi TrmIs, we discuss their similarities and differences. Although the binding modes to the N6 amino group of the adenine moiety of AdoMet are similar, using the side chains of acidic residues as well as hydrogen bonds, the positions of the amino acid residues involved in binding are diverse among the TrmIs from A. aeolicus, T. thermophilus, and P. abyssi.     

Pyramiding Bt genes for increasing resistance of cotton to two major lepidopteran pests: Spodoptera litura and Heliothis armigera

To more effectively control two major cotton insects (cotton bollworm and Spodoptera litura) and improve the efficacy of the pest resistance management, novel transgenic plants expressing Bacillus thuringiensis Cry9C gene were generated, and gene stacking strategy was incorporated. Initially, a binary plasmid vector harboring Cry9C gene was introduced into an elite cotton cultivar Simian-3 by Agrobacterium-mediated transformation. Integration and expression of the Cry9C genes in three transgenic lines were confirmed by PCR and RT-PCR. Among these transgenic lines, T0 generation of line 16 (L-16) with normal phenotypes were selected by ELISA assays for its highest expression level of Cry9C. In T1 population of L-16, the expression level of Cry9C ranged from 29 to 45 μg/g fresh leaf. The following insect bioassays demonstrated that transgenic S3-35S::Cry9C cotton plants exhibited moderate toxicity to Heliothis armigera but strong toxicity to S. litura compared with the transgenic plants expressing Cry 1Ac gene. For incorporation of gene staking strategy, Cry9C gene and Cry 2A or Cry 1Ac were pyramided, respectively by sexual crossing. The expression of Cry9C protein in all F1 progenies had a similar level as the parent plants indicating the high heritability of Bt genes in transgenic progenies. Progenies from both Cry9C × Cry 2A and Cry9C × Cry 1Ac exhibited higher resistance to S. litura compared with their parents. Together our data demonstrated that our newly generated transgenic plants represent a reservoir of novel insect-resistant materials in cotton breeding, and the successful incorporation of gene pyramiding technology can provide a new solution of developing multiple resistance management strategies.     

Response of the population size and community structure of Paenibacillus spp. to different fertilization regimes in a long-term experiment of red soil

Background and aims

Paenibacillus spp. are widely considered to impact the fertility and health of soil. The aim of this study was to evaluate how different fertilization regimes affect the population size and community structure of Paenibacillus spp. over a long period of time in red soil.

Methods

Soil samples were collected from a long-term experiment and were then analyzed using real-time PCR and PCR-DGGE. The correlation analysis, PCA and RDA were used to explore the relationships among Paenibacillus spp. population, community structure and soil properties in different treatments.

Results

The pH was seriously decreased only by the application of chemical fertilizer. The largest population of Paenibacillus spp. was found in the soil treated with organic fertilizer application, while the richest diversity was observed in the soil treated only with the chemical fertilizer. The Paenibacillus spp., Paenibacillus alkaliterrae, Paenibacillus campinasensis, and Paenibacillus xylanilyticus were found in all treatments. Paenibacillus castaneae was found in the soil treated with NPK, and Paenibacillus pabuli was specifically observed in the lime-amended treatment. Paenibacillus taichungensis and Paenibacillus prosopidis were detected in the soil treated with only chemical fertilizer. Except for the ammonium and pH, all the tested soil fertility parameters (total C, total N, nitrate, available K and available P) could significantly affect both the Paenibacillus spp. population number and diversity. The soil pH was significantly correlated with Paenibacillus spp. diversity only.

Conclusions

Our results indicate that the different long-term fertilization regimes have varied impact on both the Paenibacillus spp. population size and the diversity of the community associated with the soil properties tested. These results can help to enrich the information on the response of beneficial soil microbes to different long-term fertilization regimes.     

Common vitamin D pathway gene variants reveal contrasting effects on serum vitamin D levels in African Americans and European Americans

Vitamin D deficiency is more common among African Americans (AAs) than among European Americans (EAs), and epidemiologic evidence links vitamin D status to many health outcomes. Two genome-wide association studies (GWAS) in European populations identified vitamin D pathway gene single-nucleotide polymorphisms (SNPs) associated with serum vitamin D [25(OH)D] levels, but a few of these SNPs have been replicated in AAs. Here, we investigated the associations of 39 SNPs in vitamin D pathway genes, including 19 GWAS-identified SNPs, with serum 25(OH)D concentrations in 652 AAs and 405 EAs. Linear and logistic regression analyses were performed adjusting for relevant environmental and biological factors. The pattern of SNP associations was distinct between AAs and EAs. In AAs, six GWAS-identified SNPs in GC, CYP2R1, and DHCR7/NADSYN1 were replicated, while nine GWAS SNPs in GC and CYP2R1 were replicated in EAs. A CYP2R1 SNP, rs12794714, exhibited the strongest signal of association in AAs. In EAs, however, a different CYP2R1 SNP, rs1993116, was the most strongly associated. Our models, which take into account genetic and environmental variables, accounted for 20 and 28 % of the variance in serum vitamin D levels in AAs and EAs, respectively.