tetracycline and Infertility

The New World Screwworm fly (NWS), Cochliomyia hominivorax, is an ectoparasite of warm-blooded animals and a major pest of livestock in parts of South America and the Caribbean where it remains endemic. In North and Central America it was eradicated using the Sterile Insect Technique (SIT). A control program is managed cooperatively between the governments of the United States and Panama to prevent the northward spread of NWS from infested countries in South America. This is accomplished by maintaining a permanent barrier through the release of millions of sterile male and female flies in the border between Panama and Colombia. Our research team demonstrated the utility of biotechnology-enhanced approaches for SIT by developing a male-only strain of the NWS. The strain carried a single component tetracycline repressible female lethal system where females died at late larval/pupal stages. The control program can be further improved by removing females during embryonic development as larval diet costs are significant.. The strains developed carry a two-component system consisting of the Lucilia sericata bottleneck gene promoter driving expression of the tTA gene and a tTA-regulated Lshid proapoptotic effector gene. Insertion of the sex-specifically spliced intron from the C. hominivorax transformer gene within the Lshid gene ensures that only females die when insects are reared in the absence of tetracycline. In several double homozygous two-component strains and in one "All-in-one" strain that had both components in a single construct, female lethality occurred at the embryonic and/or first instar larval stages when raised on diet without tetracycline. Laboratory evaluation for phenotypes that are relevant for mass rearing in a production facility revealed that most strains had fitness characteristics similar to the wild type J06 strain that is currently reared for release in the permanent barrier. Testing of an "All in one" strain under mass rearing conditions showed that the strain maintained the fitness characteristics observed in small-scale rearing.. The early female lethal strains described here could be selected by the NWS Control Program for testing at large scale in the production facility to enhance the efficiency of the NWS eradication program.

Topics: Animals; Animals, Genetically Modified; Biotechnology; Diptera; Embryonic Development; Female; Genes, Lethal; Genetic Fitness; Infertility; Insect Control; Male; Promoter Regions, Genetic; Tetracycline

Reduction or elimination of vector populations will tend to reduce or eliminate transmission of vector-borne diseases. One potential method for environmentally-friendly, species-specific population control is the Sterile Insect Technique (SIT). SIT has not been widely used against insect disease vectors such as mosquitoes, in part because of various practical difficulties in rearing, sterilization and distribution. Additionally, vector populations with strong density-dependent effects will tend to be resistant to SIT-based control as the population-reducing effect of induced sterility will tend to be offset by reduced density-dependent mortality.. We investigated by mathematical modeling the effect of manipulating the stage of development at which death occurs (lethal phase) in an SIT program against a density-dependence-limited insect population. We found late-acting lethality to be considerably more effective than early-acting lethality. No such strains of a vector insect have been described, so as a proof-of-principle we constructed a strain of the principal vector of the dengue and yellow fever viruses, Aedes (Stegomyia) aegypti, with the necessary properties of dominant, repressible, highly penetrant, late-acting lethality.. Conventional SIT induces early-acting (embryonic) lethality, but genetic methods potentially allow the lethal phase to be tailored to the program. For insects with strong density-dependence, we show that lethality after the density-dependent phase would be a considerable improvement over conventional methods. For density-dependent parameters estimated from field data for Aedes aegypti, the critical release ratio for population elimination is modeled to be 27% to 540% greater for early-acting rather than late-acting lethality. Our success in developing a mosquito strain with the key features that the modeling indicated were desirable demonstrates the feasibility of this approach for improved SIT for disease control.

Topics: Aedes; Animals; Animals, Genetically Modified; Female; Genes, Dominant; Genes, Lethal; Genetic Engineering; Infertility; Larva; Longevity; Male; Models, Biological; Mosquito Control; Population Density; Pupa; Tetracycline; Time Factors

Wolbachia are maternally inherited bacteria that commonly spread through host populations by causing cytoplasmic incompatibility, often expressed as reduced egg hatch when uninfected females mate with infected males. Infected females are frequently less fecund as a consequence of Wolbachia infection. However, theory predicts that because of maternal transmission, these "parasites" will tend to evolve towards a more mutualistic association with their hosts. Drosophila simulans in California provided the classic case of a Wolbachia infection spreading in nature. Cytoplasmic incompatibility allowed the infection to spread through individual populations within a few years and from southern to northern California (more than 700 km) within a decade, despite reducing the fecundity of infected females by 15%-20% under laboratory conditions. Here we show that the Wolbachia in California D. simulans have changed over the last 20 y so that infected females now exhibit an average 10% fecundity advantage over uninfected females in the laboratory. Our data suggest smaller but qualitatively similar changes in relative fecundity in nature and demonstrate that fecundity-increasing Wolbachia variants are currently polymorphic in natural populations.

Topics: Animals; Base Sequence; Biological Evolution; California; Cytoplasm; Drosophila; Female; Fertility; Infertility; Male; Molecular Sequence Data; Tetracycline; Wolbachia

Intracellular bacteria have been described in several species of filarial nematodes, but their relationships with, and effects on, their nematode hosts have not previously been elucidated. In this study, intracellular bacteria were observed in tissues of the rodent parasite Litomosoides sigmodontis by transmission electron microscopy and by immunohistochemistry using antiendobacterial heat shock protein-60 antisera. Molecular phylogenetic analysis of the bacterial 16S ribosomal RNA gene, isolated by PCR, showed a close relationship to the rickettsial Wolbachia endobacteria of arthropods and to other filarial intracellular bacteria. The impact of tetracycline therapy of infected rodents on L. sigmodontis development was analyzed in order to understand the role(s) these bacteria might play in filarial biology. Tetracycline therapy, when initiated with L. sigmodontis infection, eliminated the bacteria and resulted in filarial growth retardation and infertility. If initiated after microfilarial development, treatment reduced filarial fertility. Treatment with antibiotics not affecting rickettsial bacteria did not inhibit filarial development. Acanthocheilonema viteae filariae were shown to lack intracellular bacteria and to be insensitive to tetracycline. These results suggest a mutualistic interaction between the intracellular bacteria and the filarial nematode. Investigation of such a mutualism in endobacteria-containing human filariae is warranted for a potential chemotherapeutic exploitation.

Topics: Animals; Bacterial Proteins; Dipetalonema; Filariasis; Filarioidea; Immunohistochemistry; Infertility; Mice; Mice, Inbred BALB C; Microscopy, Electron; Phylogeny; Rats; Rickettsia; RNA, Ribosomal, 16S; Tetracycline

Using oligonucleotide primers derived from the aligned polypeptide sequences of several prokaryotic dnaA genes, we amplified from Drosophila melanogaster DNA a 557 bp fragment containing a single open reading frame. The predicted peptide sequence shows a significant similarity to previously characterized protein sequences that are encoded by the dnaA genes of several prokaryotes. The dnaA sequences are also detectable by PCR in DNA from Drosophila simulans and Nasonia vitripennis flies which are infected by a symbiotic bacterium assigned to the type species Wolbachia pipientis. A tetracycline treatment that eradicates bacterial parasites from insects, abolishes the dnaA sequences from Drosophila and Nasonia DNA. In addition, dnaA-positive Drosophila melanogaster contain numerous rod-shaped bacteria in embryos, which are abolished in subsequent generations after treatment with tetracycline. Combined with phylogenetic analysis of DnaA and 16S rRNA sequences, these results show that the dnaA cognate comes from Wolbachia. A survey of Drosophila stocks using PCR amplification of dnaA and 16S rRNA sequences showed that Wolbachia is widely spread among D. melanogaster laboratory strains but absent from several established strains of the Mediterranean fruit fly Ceratitis capitata. Evidence is also presented that presence of the bacterium can cause partial cytoplasmic incompatibility between infected and non-infected D. melanogaster strains.

Topics: Amino Acid Sequence; Animals; Bacterial Proteins; Base Sequence; Crosses, Genetic; DNA-Binding Proteins; Drosophila; Drosophila melanogaster; Extrachromosomal Inheritance; Female; Genes, Bacterial; Infertility; Male; Molecular Sequence Data; Polymerase Chain Reaction; Sequence Alignment; Tetracycline

Cytoplasmic incompatibility (CI) describes the phenomenon whereby eggs fertilized by sperm from insects infected with a rickettsial endosymbiont fail to hatch. Unidirectional CI between conspecific populations of insects is a well documented phenomenon. Bidirectional CI has, however, only been described in mosquito populations, and recently between closely related species of parasitic wasps, where it is of interest as both an unusual form of reproductive isolation and as a potential means of insect population suppression. Here we report on the first known example of bidirectional CI between conspecific populations of Drosophila simulans. Further, we show that defects as early as the first cleavage division are associated with CI. This observation suggests that the cellular basis of CI involves disruption of processes before or during zygote formation and that CI arises from defects in the structure and/or function of the sperm during fertilization.

Topics: Animals; Drosophila; Female; Infertility; Male; Ovum; Rickettsia; Spermatozoa; Tetracycline

Slide agglutination and mercaptoethanol tube agglutination tests for canine brucellosis were performed on 158 dogs. Clinical status was compared with the serologic test results. Sera were from 56 clinically normal dogs, 63 dogs with reproductive disorders, and 39 dogs with various nonreproductive disorders that could be associated with canine brucellosis. Ten of 21 (48%) aborting bitches and 2 of 9 (22%) bitches with other reproductive disorders were seropositive for brucellosis. Enlarged testicles, orchitis, and epididymitis were the main clinical disorders associated with positive (33%) or suspect (20%) serologic reactions in 15 male dogs. In 13 dogs of both sexes, diskospondylitis and osteomyelitis were the most common nonreproductive disorders associated with seropositive status for canine brucellosis (46%). Of 138 stray dogs, 17 were seropositive for canine brucellosis. Treatment of seropositive animals with antibiotics gave variable results. Of the 296 serum samples tested, 43 (14.5%) gave a positive reaction by the slide agglutination test but were negative by the mercaptoethanol tube agglutination test. Correlation was not found between serologic results and sex or breed.

Topics: Abortion, Veterinary; Agglutination Tests; Animals; Brucellosis; Dog Diseases; Dogs; Female; Infertility; Male; Minocycline; Pregnancy; Tetracycline

Maternally inherited variants, which arose within a laboratory colony of Culex pipiens fatigans, have been studied by rearing cultures from single egg rafts. Segregation, i.e, variation of cytoplasmic incompatibility properties between the male progeny of individual females, was demonstrated. Also, from the daughters of individual females, sub-lines were derived within which all the males showed the same incompatibility or compatibility properties. Among the descendants of tetracycline-treated individuals were lines which superficially simulated these phenomena, but theses lines ultimately reverted to the cytoplasmic compatibility type of the strain which was submitted to the treatment. The types of variation s in cytoplasmic incompatibility properties that have been studied are discussed.

Topics: Animals; Crosses, Genetic; Culex; Extrachromosomal Inheritance; Female; Humans; Infertility; Male; Tetracycline

Topics: Cervix Uteri; Female; Humans; Infertility; Infertility, Female; Infertility, Male; Male; Mycoplasma; Pregnancy; Spermatozoa; Tetracycline

Topics: Cervix Uteri; Female; Fertilization; Humans; Infertility; Infertility, Female; Infertility, Male; Male; Mycoplasma; Pregnancy; Semen; Tetracycline

Topics: Bacillus subtilis; Chemical Phenomena; Chemistry, Physical; Dihydrostreptomycin Sulfate; Escherichia coli; Female; Filtration; Glycolates; Infertility; Male; Membranes, Artificial; Penicillin G; Pharmacopoeias as Topic; Polymyxins; Serratia marcescens; Sorbitol; Staphylococcus; Streptococcus pyogenes; Tetracycline; Thioglycolates; United Kingdom; United States; United States Food and Drug Administration

Topics: Anti-Bacterial Agents; Antibiotics, Antitubercular; Female; Fertility; Humans; Infertility; Infertility, Male; Male; Pelvic Inflammatory Disease; Penicillins; Protein Synthesis Inhibitors; Spermatozoa; Streptomycin; Tetracycline; Uterine Cervicitis