Male Mating Competitiveness of a Wolbachia-Introgressed Aedes polynesiensis Strain under Semi-Field Conditions

Aedes polynesiensis is the primary mosquito vector of lymphatic filariasis (LF) in the island nations of the South Pacific. Control of LF in this region of the world is difficult due to the unique biology of the mosquito vector. A proposed method to control LF in the Pacific is through the release of male mosquitoes that are effectively sterile. In order for this approach to be successful, it is critical that the modified male mosquitoes be able to compete with wild type male mosquitoes for female mates. In this study the authors examined the mating competitiveness of modified males under semi-field conditions. Modified males were released into field cages holding field-collected, virgin females and field collected wild type males. The resulting proportion of eggs that hatched was inversely related to the number of modified males released into the cage, which is consistent with the hypothesized competitiveness of modified males against indigenous males. The outcome indicates that mass release of modified A. polynesiensis mosquitoes could result in the suppression of A. polynesiensis populations and supports the continued development of applied strategies for suppression of this important disease vector

Mating competitiveness of sterile genetic sexing strain males (GAMA) under laboratory and semi-field conditions: Steps towards the use of the Sterile Insect Technique to control the major malaria vector Anopheles arabiensis in South Africa

BACKGROUND : Anopheles arabiensis Patton is primarily responsible for malaria transmission in South Africa after successful suppression of other major vector species using indoor spraying of residual insecticides. Control of An. arabiensis using current insecticide based approaches is proving difficult owing to the development of insecticide resistance, and variable feeding and resting behaviours. The use of the sterile insect technique as an area-wide integrated pest management system to supplement the control of An. arabiensis was proposed for South Africa and is currently under investigation. The success of this technique is dependent on the ability of laboratory-reared sterile males to compete with wild males for mates. As part of the research and development of the SIT technique for use against An. arabiensis in South Africa, radio-sensitivity and mating competitiveness of a local An. arabiensis sexing strain were assessed. METHODS : The optimal irradiation dose inducing male sterility without compromising mating vigour was tested using Cobalt 60 irradiation doses ranging from 70-100 Gy. Relative mating competitiveness of sterile laboratory-reared males (GAMA strain) compared to fertile wild-type males (AMAL strain) for virgin wild-type females (AMAL) was investigated under laboratory and semi-field conditions using large outdoor cages. Three different sterile male to fertile male to wild-type female ratios were evaluated [1:1:1, 5:1:1 and 10:1:1 (sterile males: fertile, wild-type males: fertile, wild-type females)]. RESULTS : Irradiation at the doses tested did not affect adult emergence but had a moderate effect on adult survivorship and mating vigour. A dose of 75 Gy was selected for the competitiveness assays. Mating competitiveness experiments showed that irradiated GAMA male mosquitoes are a third as competitive as their fertile AMAL counterparts under semi-field conditions. However, they were not as competitive under laboratory conditions. An inundative ratio of 10:1 induced the highest sterility in the representative wild-type population, with potential to effectively suppress reproduction. CONCLUSION : Laboratory-reared and sterilised GAMA male An. arabiensis at a release ratio of 3:1 (3 sterile males to 1 wild, fertile male) can successfully compete for insemination of wild-type females. These results will be used to inform subsequent small-scale pilot field releases in South Africa.The Nuclear Technologies in Medicine and the Bioscience Initiatives (NTeMBI), a national platform developed and managed by the South African Nuclear Energy Corporation and supported by the Department of Science and Technology. Funding was also provided in part from the National Research Foundation, the International Atomic Energy Agency (Contracts 17904, SAF5013 and SAF16780/ under the G34002) and a Global Diseases Detection/CDC grant (U19GH000622-01 MAL01).http://www.parasitesandvectors.comam2016Paraclinical Science

Growth-Rate Dependence Reveals Design Principles of Plasmid Copy Number Control

Genetic circuits in bacteria are intimately coupled to the cellular growth rate as many parameters of gene expression are growth-rate dependent. Growth-rate dependence can be particularly pronounced for genes on plasmids; therefore the native regulatory systems of a plasmid such as its replication control system are characterized by growth-rate dependent parameters and regulator concentrations. This natural growth-rate dependent variation of regulator concentrations can be used for a quantitative analysis of the design of such regulatory systems. Here we analyze the growth-rate dependence of parameters of the copy number control system of ColE1-type plasmids in E. coli. This analysis allows us to infer the form of the control function and suggests that the Rom protein increases the sensitivity of control

The amino acid substitution and some chemical properties of a variant human erythrocyte carbonic anhydrase: Carbonic anhydrase Id Michigan

Carbonic anhydrase Id Michigan , an electrophoretic variant of human red cell carbonic anhydrase I, was purified from erythrocytes obtained from an individual heterozygous for the trait. Primary structural analysis indicates that a lysine residue has exchanged for a threonine residue in the variant enzyme. After isolation, there was approximately 1.8 times as much normal as variant enzyme. Thermostability studies demonstrated that carbonic anhydrase Id was more thermolabile than the normal enzyme. The normal and variant enzymes showed no differences in specific carboxylesterase activity or CO 2 hydratase activity. Utilizing the carboxylesterase activity toward β-naphthyl acetate, the normal and variant enzymes had similar Michaelis constants, p H profiles, and rates of inhibition by acetazolamide. Immunochemical studies did not demonstrate an antigenic difference for the variant enzyme.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/44117/1/10528_2004_Article_BF00486517.pd

Actinomycete integrative and conjugative elements

This paper reviews current knowledge on actinomycete integrative and conjugative elements (AICEs). The best characterised AICEs, pSAM2 of Streptomyces ambofaciens (10.9 kb), SLP1 (17.3 kb) of Streptomyces coelicolor and pMEA300 of Amycolatopsis methanolica (13.3 kb), are present as integrative elements in specific tRNA genes, and are capable of conjugative transfer. These AICEs have a highly conserved structural organisation, with functional modules for excision/integration, replication, conjugative transfer, and regulation. Recently, it has been shown that pMEA300 and the related elements pMEA100 of Amycolatopsis mediterranei and pSE211 of Saccharopolyspora erythraea form a novel group of AICEs, the pMEA-elements, based on the unique characteristics of their replication initiator protein RepAM. Evaluation of a large collection of Amycolatopsis isolates has allowed identification of multiple pMEA-like elements. Our data show that, as AICEs, they mainly coevolved with their natural host in an integrated form, rather than being dispersed via horizontal gene transfer. The pMEA-like elements could be separated into two distinct populations from different geographical origins. One group was most closely related to pMEA300 and was found in isolates from Australia and Asia and pMEA100-related sequences were present in European isolates. Genome sequence data have enormously contributed to the recent insight that AICEs are present in many actinomycete genera. The sequence data also provide more insight into their evolutionary relationships, revealing their modular composition and their likely combined descent from bacterial plasmids and bacteriophages. Evidence is accumulating that AICEs act as modulators of host genome diversity and are also involved in the acquisition of secondary metabolite clusters and foreign DNA via horizontal gene transfer. Although still speculative, these AICEs may play a role in the spread of antibiotic resistance factors into pathogenic bacteria. The novel insights on AICE characteristics presented in this review may be used for the effective construction of new vectors that allows us to engineer and optimise strains for the production of commercially and medically interesting secondary metabolites, and bioactive proteins