Structural characterization and assembly of the distal tail structure of the temperate lactococcal bacteriophage TP901-1

The tail structures of bacteriophages infecting gram-positive bacteria are largely unexplored, although the phage tail mediates the initial interaction with the host cell. The temperate Lactococcus lactis phage TP901-1 of the Siphoviridae family has a long noncontractile tail with a distal baseplate. In the present study, we investigated the distal tail structures and tail assembly of phage TP901-1 by introducing nonsense mutations into the late transcribed genes dit (orf46), tal(TP901-1) (orf47), bppU (orf48), bppL (orf49), and orf50. Transmission electron microscopy examination of mutant and wild-type TP901-1 phages showed that the baseplate consisted of two different disks and that a central tail fiber is protruding below the baseplate. Evaluation of the mutant tail morphologies with protein profiles and Western blots revealed that the upper and lower baseplate disks consist of the proteins BppU and BppL, respectively. Likewise, Dit and Tal(TP901-1) were shown to be structural tail proteins essential for tail formation, and Tal(TP901-1) was furthermore identified as the tail fiber protein by immunogold labeling experiments. Determination of infection efficiencies of the mutant phages showed that the baseplate is fundamental for host infection and the lower disk protein, BppL, is suggested to interact with the host receptor. In contrast, ORF50 was found to be nonessential for tail assembly and host infection. A model for TP901-1 tail assembly, in which the function of eight specific proteins is considered, is presented.     

Temperature tolerance and thyroid activity of the white perch Roccus (=Morone) americanus

The seasonaliy of temperature tolerance using thiourea-treated, normal and thyroxine treated white perch was determined after laboratory acclimation and LD50 values calculated by normit analysis. Treatment effects, reflected in slight shifts in LD50 values were evident. However, these did not fit a consistent pattern of thyroidal involvement in temperature tolerance.
When specimens of known thyroidal functional state were used in tolerance tests, results, similar to the seasonal tolerance tests, were obtained. Thus, although the white perch has a functioning thyroid capable of forming radiohormone and this capability was experimentally varied in these tests, no tolerance shifts were noted.
Data obtained in tolerance testing were statistically adjusted to partition out variation due to differences in acclimation temperatures (season) and to test for treatment (thyroidal functional state) effects. Treatment difference was not significant while that due to season was significant (P<0.01). Thyroidal functional state was thus unrelated to tolerance.     

Biology and host range of Omolabus piceus, a weevil rejected for biological control for Schinus terebinthifolius in the USA

Surveys for biological control agents of the invasive weed Schinus terebinthifolius (Anacardiaceae) discovered two Omolabus weevils (Coleoptera: Attelabidae) feeding on the plant in its native range. Molecular and morphological analysis indicated that one of these species consistently fed on the target weed and the other species fed more broadly. Aspects of the biology and host range of the more specific species, Omolabus piceus (Germar) were examined to determine its suitability as a biological control agent of S. terebinthifolius in the USA. Adults feed on newly formed leaves, and eggs, larvae and pupae develop in curled fragments of leaves, called nidi. Larvae consumed an average of 11.3 (±0.4) mg throughout their development which required 15.1 (±0.2) days. An average of 31.6 (±2.7) eggs were laid per female during their 23.8 (±2.2) day lifetime, after a 3.4 (±1.0) day preoviposition period. In no-choice tests, O. piceus adults fed and oviposited on all tested native North American, Caribbean and agricultural Anacardiaceae species except for M. indica. The field host-range of O. piceus, as determined by samples of host use in the native range, included three Schinus, two Lithrea and one Anacardium species. Therefore, we do not recommend O. piceus for biological control of S. terebinthifolius in the USA. However, the utilization of this species in other infested areas such as Hawaií and Australia should be considered.     

Suitability for classical biological control of Hedychium coronarium in Argentina

BioControl - Hedychium coronarium (Zingiberales: Zingiberaceae), native to the Himalayas and southern China, has become an environmental weed in many countries around the world. Reported in several...     

Molecular identification of the exotic slug <Emphasis Type="Italic">Arion subfuscus</Emphasis> sensu stricto (Gastropoda: Pulmonata) in California,with comments on the source location of introduced populations

Arion subfuscus sensu lato (s. l.) refers to a cryptic slug species complex that is native to Europe and which, from there, has been introduced into the northeastern U.S. The species complex was detected in California for the first time in 2005 and recently 12 specimens were collected during statewide surveys. The genital morphology of these specimens suggested that only A. subfuscus sensu stricto (s. s.) was present and partial sequences of mitochondrial 16S rDNA (443 bp) showed that they all belonged to a single haplotype of the mitochondrial lineage, S1 sensu Pinceel et al. (Genetica 125: 155–171, 2005). This result was corroborated by a parallel analysis of a 655 bp COI DNA barcode. The 16S rDNA S1 haplotype (S1-03) of the Californian specimens is hitherto known only from the northeastern U.S. Hence, it is likely that populations may have been introduced to California from the northeastern states, rather than directly from the native area of the S1 haplogroup in Europe.     

HORIZONTAL GENE TRANSFER AND THE EVOLUTION OF BACTERIAL COOPERATION

Bacteria frequently exhibit cooperative behaviors but cooperative strains are vulnerable to invasion by cheater strains that reap the benefits of cooperation but do not perform the cooperative behavior themselves. Bacterial genomes often contain mobile genetic elements such as plasmids. When a gene for cooperative behavior exists on a plasmid, cheaters can be forced to cooperate by infection with this plasmid, rescuing cooperation in a population in which mutation or migration has allowed cheaters to arise. Here we introduce a second plasmid that does not code for cooperation and show that the social dilemma repeats itself at the plasmid level in both within‐patch and metapopulation scenarios, and under various scenarios of plasmid incompatibility. Our results suggest that although plasmid carriage of cooperative genes can provide a transient defense against defection in structured environments, plasmid and chromosomal defection remain the only stable strategies in an unstructured environment. We discuss our results in the light of recent bioinformatic evidence that cooperative genes are overrepresented on mobile elements.     

An assessment of pathogen removal during composting of the separated solid fraction of pig manure

The aim was to investigate pathogen survival during composting of pig manure solids with and without bulking agents in two trials of 56 days duration, each with four treatments. Salmonella was detected in the sawdust and straw bulking agents but was undetectable in the compost, except in one treatment at day 0. Enteric indicator organisms were reduced by day 7 (P<0.001) and were undetectable in the final compost, except for coliform which were present at 3.66-4.43 log?? CFU/g. Yeasts and moulds were reduced and aerobic spore-formers remained stable in one trial but both increased in the other (P<0.001). Bacillus licheniformis and Clostridium sporogenes were the predominant culturable spore-forming bacteria recovered. Microbial counts were influenced by the bulking agent but only at particular time points (P<0.05). Overall, the pig manure-derived compost complied with EU regulations for processed manure products, as E. coli and Enterococcus were below limits and it was Salmonella-free.