Population genetics of Wolbachia‐infected,parthenogenetic and uninfected,sexual populations of Tetrastichus coeruleus (Hymenoptera: Eulophidae)

Wolbachia are endosymbiotic bacteria known to manipulate the reproduction of their hosts. These manipulations are expected to have consequences on the population genetics of the host, such as heterozygosity levels, genetic diversity and gene flow. The parasitoid wasp Tetrastichus coeruleus has populations that are infected with parthenogenesis‐inducing Wolbachia and populations that are not infected. We studied the population genetics of T. coeruleus between and within Wolbachia‐infected and uninfected populations, using nuclear microsatellites and mitochondrial DNA. We expected reduced genetic diversity in both DNA types in infected populations. However, migration and gene flow could introduce new DNA variants into populations. We therefore paid special attention to individuals with unexpected (genetic) characteristics. Based on nuclear and mitochondrial DNA, two genetic clusters were evident: a thelytokous cluster containing all Wolbachia‐infected, parthenogenetic populations and an arrhenotokous cluster containing all uninfected, sexual populations. Nuclear and mitochondrial DNA did not exhibit concordant patterns of variation, although there was reduced genetic diversity in infected populations for both DNA types. Within the thelytokous cluster, there was nuclear DNA variation, but no mitochondrial DNA variation. This nuclear DNA variation may be explained by occasional sex between infected females and males, by horizontal transmission of Wolbachia, and/or by novel mutations. Several females from thelytokous populations were uninfected and/or heterozygous for microsatellite loci. These unexpected characteristics may be explained by migration, by inefficient transmission of Wolbachia, by horizontal transmission of Wolbachia, and/or by novel mutations. However, migration has not prevented the build‐up of considerable genetic differentiation between thelytokous and arrhenotokous populations.     

Application of stains in clinical microbiology

Stains have been used for diagnosing infectious diseases since the late 1800s. The Gram stain remains the most commonly used stain because it detects and differentiates a wide range of pathogens. The next most commonly used diagnostic technique is acid-fast staining that is used primarily to detect Mycobacterium tuberculosis and other severe infections. Many infectious agents grow slowly on culture media or may not grow at all; stains may be the only method to detect these organisms in clinical specimens. In the hands of experienced clinical microscopists, stains provide rapid and cost-effective information for preliminary diagnosis of infectious diseases. A review of the most common staining methods used in the clinical microbiology laboratory is presented here.     

Effects of fungicide treatment and vacuuming on pyroglyphid mites and their allergens in mattress dust

House-dust mites (Pyroglyphidae) are an important source of indoor airborne allergens. Several methods may be applied to reduce the population growth of these mites and thus the quantity of allergen formed. One such method is to interfere with the mites' food chain. Fungi are a key factor in this food chain: they serve as an indirect food source. In this study we investigated the results of the repeated application of a fungicide (natamycin) on mattresses. As controls we treated some mattresses with a placebo, while others were left untreated. The application of natamycin appeared to hamper mite development. Additional vacuuming reduced the quantity of mite allergens present. In the usual household situation repeated treatment will be necessary to obtain a long-term reduction.