Broad host range plasmid-based gene transfer system in the cyanobacterium Gloeobacter violaceus which lacks thylakoids

Gloeobacter violaceus, a cyanobacterium lack of thylakoids, is refractory to genetic manipulations because its cells are enveloped by a thick gelatinous sheath and in colonial form. In this study, a large number of single cells were obtained by repeated pumping with a syringe with the gelatinous sheath removed. And an exogenous broad host range plasmid pKT210 was conjugatively transferred into G. violaceus. Analyses with dot-blot hybridization and restriction mapping showed that the exogenous plasmid pKT210 had been introduced into G. violaceus and stably maintained with no alteration in its structure. pKT210 extracted from G. violaceus exconjugants could be transformed into the mcr - mrr - E. coli strain DH10B but not the mcr(+) mrr(+) strain DH5alpha, which suggests that a methylase system may be present in G. violaceus.

Comparative Analysis of Fatty Acid Desaturases in Cyanobacterial Genomes

Fatty acid desaturases are enzymes that introduce double bonds into the hydrocarbon chains of fatty acids. The fatty acid desaturases from 37 cyanobacterial genomes were identified and classified based upon their conserved histidine-rich motifs and phylogenetic analysis, which help to determine the amounts and distributions of desaturases in cyanobacterial species. The filamentous or N-2-fixing cyanobacteria usually possess more types of fatty acid desaturases than that of unicellular species. The pathway of acyl-lipid desaturation for unicellular marine cyanobacteria Synechococcus and Prochlorococcus differs from that of other cyanobacteria, indicating different phylogenetic histories of the two genera from other cyanobacteria isolated from freshwater, soil, or symbiont. Strain Gloeobacter violaceus PCC 7421 was isolated from calcareous rock and lacks thylakoid membranes. The types and amounts of desaturases of this strain are distinct to those of other cyanobacteria, reflecting the earliest divergence of it from the cyanobacterial line. Three thermophilic unicellular strains, Thermosynechococcus elongatus BP-1 and two Synechococcus Yellowstone species, lack highly unsaturated fatty acids in lipids and contain only one Delta 9 desaturase in contrast with mesophilic strains, which is probably due to their thermic habitats. Thus, the amounts and types of fatty acid desaturases are various among different cyanobacterial species, which may result from the adaption to environments in evolution. Copyright (c) 2008 Xiaoyuan Chi et al.

“Best interests” and withholding and withdrawing life-sustaining treatment from an adult who lacks capacity in the parens patriae jurisdiction

Disputes about withholding and withdrawing life-sustaining treatment are increasingly coming before Australian Supreme Courts. Such cases are generally heard in the parens patriae jurisdiction where the test applied is what is in the patient’s “best interests”. However, the application of the “best interests” test, and its meaning, remains unclear in this context. To shed light on this emerging body of jurisprudence, this article analyses the Australian superior court decisions that consider an adult’s best interests in the context of decisions about life-sustaining treatment. We identify a number of themes from the current body of cases and consider how these themes may guide future decision-making. After then considering the law in the United Kingdom, we suggest an approach for assessing best interests that could be adopted by Australian Supreme Courts. We argue that the suggested approach will lead to a more structured and systematic decision-making process that better promotes the best interests of the patient.

Clostridium difficile Ribotype 023 Lacks the Ability To Hydrolyze Esculin, Leading to False-Negative Results on Chromogenic Agar

41.Connor, M.C., Fairley, D.J. Marks, N.J. McGrath, J.W. (2016) Clostridium difficile Ribotype 023 lacks the ability to hydrolyse esculin, leading to false negative results on chromogenic agar. Letters in Applied Microbiology

Mating behavior of Sickius longibulbi (Araneae, Theraphosidae, Ischnocolinae), a spider that lacks spermathecae

We describe the mating behavior in the spermatheca-lacking theraphosid species Sickius longibulbi Soares & Camargo 1948. The behavior in captivity of nine pairs of S. longibulbi was videotaped and analyzed. The matting of this species presented an uncommon theraphosid pattern. There is little in the way of overt courtship by the male, the primary behavior seen being the male`s use of legs I and II to touch the female`s first pairs of legs and her chelicerae. Sometimes the male clasped one of the female`s first pairs of legs, bringing her close to him. While the female raised her body, the male clasped her fangs and held her tightly with his legs III wrapped around her prosoma. The male seemed to try to knock the female down, pushing her entire body until she lay on her dorsum. In this phase we observed the male biting the female on the sternum or on the leg joints. When the female fell, the male attempted to position himself at an angle of 90 degrees from the female. These movements appear to demand a lot of energy, particularly because the female is not passive during the mating. Our findings suggest that copulating in this position is, for the male, more successful than adopting other positions because it allows his extremely long palpal bulbs to deposit more sperm in the female oviduct where - since she lacks spermathecae - she retains the sperm. We suggest that the further he reaches into the oviduct, the greater the chance that he will fertilize the female`s eggs.

The South American Plasmodium falciparum var gene repertoire is limited, highly shared and possibly lacks several antigenic types

The Plasmodium falciparum var gene family encodes large variant antigens, which are important virulence factors, and also targets of the humoral host response. The frequently observed mild outcomes of falciparum malaria in many places of the Amazon area prompted us to ask whether a globally restricted variant (var) gene repertoire is present in currently circulating and older isolates of this area. By exhaustive analysis of var gene tags from 89 isolates and clones taken during many years from all over the Brazilian Amazon, we estimate that there are probably no more than 350-430 distinct sequence types, less than for any similar sized area studied so far. Detailed analysis of the var tags from genetically distinct clones obtained from single isolates revealed restricted and redundant repertoires suggesting either a low incidence of infective bites or restricted variant gene diversity in inoculated parasites. Additionally, we found a structuring of var gene repertoires observed as a higher pairwise typing sharing in isolates from the same microregion compared to isolates from different regions. Fine analysis of translated var tags revealed that certain Distinct Sequence Identifiers (DSIDs) were differently represented in Brazilian/South American isolates when compared to datasets from other continents. By global alignment of worldwide var DBL alpha sequences and sorting in groups with more than 76% identity, 125 clusters were formed and more than half of all genes were found in nine clusters with 50 or more sequences. While Brazilian/South American sequences were represented only in 64 groups, African sequences were found in the majority of clusters. DSID type 1 related sequences accumulated almost completely in one single cluster, indicating that limited recombination occurs in these specific var gene types. These data demonstrate the so far highest pairwise type sharing values for the var gene family in isolates from all over an entire subcontinent. The apparent lack of specific sequences types suggests that the P. falciparum transmission dynamics in the whole Amazon are probably different from any other endemic region studied and possibly interfere with the parasite`s ability to efficiently diversify its variant gene repertoires. (C) 2010 Elsevier B.V. All rights reserved.