Bulky DNA adducts in human sperm: relationship with fertility,semen quality,smoking, and environmental factors

The integrity of DNA of spermatogenic cells can be affected by endogenous and exogenous genotoxic factors. Resulting DNA damage in spermatozoa may significantly contribute to impaired fertility. Here, the 32P-postlabeling method was used to analyze the levels of bulky DNA adducts in sperm cells in a group of 179 males, either healthy donors or patients with an impaired fertility. When all donors were analyzed, the levels of bulky DNA adducts was 1.2-fold higher in smokers than in non-smokers, but the difference was not statistically significant (P=0.054). However, a statistically significant difference existed between current smokers and never smokers among the healthy individuals (1.7-fold increase, P=0.008). No correlation between alcohol or coffee consumption and sperm DNA adducts was found. The levels of DNA adducts in sperm seemed to be unaffected by environmental and occupational factors. On the other hand, groups of healthy persons and patients with male-factor infertility differed significantly with respect to the level of bulky DNA adducts (P=0.012). A significant negative correlation between DNA adducts and sperm concentration or sperm motility existed among patients with an impaired fertility (n=93; P<0.029, r(S)=-0.225). These results suggest that DNA adducts in sperm cells can be applied as potential biomarkers in studies of human infertility.     

The Argasidae, Ixodidae and Nuttalliellidae (Acari: Ixodida): A World List of Valid Tick Names

The world's argasid tick fauna comprises 183 species in four genera, namely Argas, Carios, Ornithodoros and Otobius in the family Argasidae. The ixodid tick fauna consists of 241 species in the genus Ixodes and 442 species in the genera Amblyomma, Anomalohimalaya, Bothriocroton, Cosmiomma, Dermacentor, Haemaphysalis, Hyalomma, Margaropus, Nosomma, Rhipicentor and Rhipicephalus in the family Ixodidae, with the genus Boophilus becoming a subgenus of the genus Rhipicephalus. The family Nuttalliellidae is represented by the monospecific genus Nuttalliella. The species names of these ticks, based on seven previous complete or partial listings, as well as those of recently described new species, are presented in tabular format. This revised version was published online in July 2006 with corrections to the Cover Date.     

Ixodid ticks feeding on humans in South Africa: with notes on preferred hosts,geographic distribution,seasonal occurrence and transmission of pathogens

This paper records the identities of 558 ixodid ticks feeding on 194 humans in South Africa. These ticks belonged to 20 species in six genera and those most frequently encountered were Amblyomma hebraeum, Haemaphysalis leachi, Hyalomma marginatum rufipes, Hyalomma truncatum, Rhipicephalus appendiculatus, Rhipicephalus gertrudae and Rhipicephalus simus. With the exception of the larvae of R. appendiculatus, the incidents of these ticks feeding on humans correlated well with their seasonal occurrences on preferred hosts. Ticks were also collected at monthly intervals, for 14 consecutive months, from the clothing of a game-guard providing protection for field-workers engaged in the collection, by means of flannel strips, of free-living ticks from the vegetation of four localities in the southern region of the Kruger National Park. In addition, with the exception of 3 months when the particular worker was absent, ticks that fed on one of the field-workers were collected over the same 14-month period. A total of 54,429 free-living ticks belonging to 14 species and six genera were collected from the vegetation at the four localities during this time and 3751 ticks belonging to 11 species and six genera from the clothing of the game-guard. The larvae of A. hebraeum and Boophilus decoloratus were the most numerous of the immature ticks, and H. leachi and R. simus of the adults on both the vegetation and the guard’s clothing. Ticks fed on the field-worker on six occasions and 14 were collected, all of which were A. hebraeum larvae. This revised version was published online in July 2006 with corrections to the Cover Date.     

The growth of sheep scab lesions in relation to sheep breed and time of the year

Numerically equal groups of between five and ten young Merino and Dorper sheep were artificially infested with sheep scab mites, Psoroptes ovis. Separate groups of sheep were infested during the early winter of two successive years as well as during the early summer of the second year. Lesion growth was measured at two-weekly intervals for a period of six weeks during the first winter and for eight weeks during the second winter and in the summer. The rate of lesion growth and mean lesion size on Merino sheep was significantly greater than that on Dorper sheep at each two-weekly recording during the winter of both years. The rate of growth of the lesions did not differ significantly between the two sheep breeds during summer, although, with the exception of eight weeks post-infestation, the mean lesion size on Merino sheep was significantly larger than that on Dorper sheep at each assessment. This revised version was published online in July 2006 with corrections to the Cover Date.     

Fumonisins--novel mycotoxins with cancer-promoting activity produced by Fusarium moniliforme.

Cultures on corn of Fusarium moniliforme MRC 826 are known to cause leukoencephalomalacia in horses and to be toxic and hepatocarcinogenic in rats. Culture material of this F. moniliforme isolate has also been shown to exhibit cancer-promoting activity in a short-term cancer initiation-promotion bioassay with diethylnitrosamine-initiated rats and the induction of gamma-glutamyl-transpeptidase-positive (GGT+) foci as an endpoint after 4 weeks of promotion. This bioassay was used as a monitoring system to isolate cancer-promoting compounds from cultures of F. moniliforme MRC 826. Culture material was successively extracted with ethyl acetate and CH3OH-H2O (3:1). Most of the cancer-promoting activity was recovered in the CH3OH-H2O extract and remained in the aqueous phase following partitioning of this extract between CH3OH-H2O (1:3) and CHCl3. The CH3OH-H2O fraction was chromatographed on an Amberlite XAD-2 column, and the active fraction was eluted with CH3OH. This fraction was chromatographed on a silica gel column with CHCl3-CH3OH-CH3COOH (6:3:1) as eluent and further purified on a C18 reverse-phase column. Two pure compounds were isolated, and these have been chemically characterized and given the trivial names fumonisin B1 and B2. At least 2 g of the major compound fumonisin B1 was purified from 1 kg of culture material. Fumonisin B1 in the diet (0.1%) significantly (P less than 0.001) induced the formation of GGT+ foci in the livers of initiated as well as noninitiated rats.(ABSTRACT TRUNCATED AT 250 WORDS)     

Association of p60fyn with middle tumor antigen in murine polyomavirus-transformed rat cells.

Rabbit antisera raised against human FYN-specific peptides were used to evaluate the expression of the fyn gene product in normal and murine polyomavirus middle tumor antigen (MTAg)-transformed rat cells. The antisera were capable of detecting p60fyn in both normal and MTAg-transformed cells. Two different antisera directed against unique p60fyn sequences were found to detect p60fyn-MTAg complexes in cell lysates from the MTAg-transformed cells. The MTAg molecules immunoprecipitated by FYN antisera were phosphorylated on tyrosine during immune-complex kinase reactions at sites similar to those found on MTAg in complexes with pp60c-src. Whereas the abundance of p60fyn was estimated to be less in the MTAg-transformed cells than in their normal counterparts, the specific activities of p60fyn molecules in the normal and transformed cells were similar.     

Targeted inactivation of the tetraspanin CD37 impairs T-cell-dependent B-cell response under suboptimal costimulatory conditions

CD37 is a membrane protein of the tetraspanin superfamily, which includes CD9, CD53, CD63, CD81, and CD82. Many of these molecules are expressed on leukocytes and have been implicated in signal transduction, cell-cell interactions, and cellular activation and development. We generated and analyzed mice deficient for CD37. Despite the high expression of CD37 on cells of the immune system, no changes in development and cellular composition of lymphoid organs were observed in mice lacking CD37. Analyses of humoral immune responses revealed a reduced level of immunoglobulin G1 (IgG1) in the sera of nonimmunized mice and an alteration of responses to T-cell-dependent antigens. Antibody responses to model antigen administered in the absence of adjuvant and to viral infections were generally poor in CD37-deficient mice. These poor antibody responses could be overcome by the immunization of antigen together with adjuvant. These results suggest a role for CD37 in T-cell-B-cell interactions which manifests itself under suboptimal costimulatory conditions.     

Studies of the cryptic allylic pyrophosphate isomerase activity of trichodiene synthase using the anomalous substrate 6,7-dihydrofarnesyl pyrophosphate

Two enantiomeric analogues of farnesyl pyrophosphate (1) were tested as inhibitors and anomalous substrates of trichodiene synthase, which catalyzes the cyclization of trans,trans-farnesyl pyrophosphate (1) to the sesquiterpene hydrocarbon trichodiene (2). The reaction has been shown to involve preliminary isomerization of 1 to the tertiary allylic isomer nerolidyl pyrophosphate (3) which is cyclized without detectable release of the intermediate from the active site of the cyclase. Both (7S)-trans-6,7-dihydrofarnesyl pyrophosphate (7a) and (7R)-trans-6,7-dihydrofarnesyl pyrophosphate (7b), prepared from (3R)- and (3S)- citronellol (9a and 9b), respectively, proved to be modest competitive inhibitors of trichodiene synthase. The values of Ki(7a), 395 nM, and Ki(7b), 220 nM, were 10-15 times the observed Km for 1 and half the Ki of inorganic pyrophosphate alone. Incubation of either 7a or 7b with trichodiene synthase resulted in formation of a mixture of products which by radio/gas-liquid chromatographic and GC/selected ion mass spectrometric analysis was shown to be composed of 80-85% isomeric trienes 19-21 and 15-20% allylic alcohols 12 and 18. Examination of the water-soluble products resulting from incubation of 7a also revealed the generation of 24% of the isomeric cis-6,7-dihydrofarnesyl pyrophosphate (26). The combined rate of formation of anomalous alcoholic and olefinic products was 10% the Vmax determined for the conversion of 1 to 2. The results can be explained by initial enzyme-catalyzed isomerization of dihydrofarnesyl pyrophosphate (7) to the corresponding tertiary allylic isomer dihydronerolidyl pyrophosphate (8). Since the latter intermediate is unable to cyclize due to the absence of the 6,7-double bond, ionization of 8 and quenching of the resulting ion pair by deprotonation, capture of water, or collapse to the isomeric primary pyrophosphate esters will generate the observed spectrum of anomalous products.