Phylogenetic analysis of cichlid fishes using nuclear DNA markers

The recent explosive adaptive radiation of cichlids in the great lakes of Africa has attracted the attention of both morphologists and molecular biologists. To decipher the phylogenetic relationships among the various taxa within the family Cichlidae is a prerequisite for answering some fundamental questions about the nature of the speciation process. In the present study, we used the random amplification of polymorphic DNA (RAPD) technique to obtain sequence differences between selected cichlid species. We then designed specific primers based on these sequences and used them to amplify template DNA from a large number of species by the polymerase chain reaction (PCR). We sequenced the amplified products and searched the sequences for indels and shared substitutions. We identified a number of such characters at three loci-- DXTU1, DXTU2, and DXTU3--and used them for phylogenetic and cladistic analysis of the relationships among the various cichlid groups. Our studies assign an outgroup position to Neotropical cichlids in relation to African cichlids, provide evidence for a sister-group relationship of tilapiines to the haplochromines, group Cyphotilapia frontosa with the lamprologines of Lake Tanganyika, place Astatoreochromis alluaudi to an outgroup position with respect to other haplochromines of Lakes Victoria and Malawi, and provide additional support for the monophyly of the remaining Lake Victoria haplochromines and the Lake Malawi haplochromines. The described approach holds great promise for further resolution of cichlid phylogeny.      

MATING BEHAVIOR OF THE CAT FLEA, CTENOCEPHALIDES FELZS BOUCHE(SIPHONAPTERA:PULICIDAE) AND MALE RESPONSE TO FEMALE EXTRACT ON AN ARTIFICIAL FEEDING SYSTEM

Abstract  The mating behavior of cat flea, Ctenocepholides felis (Bouche) was studied on an artificial feeding device. Male and female can mate repeatedly with same partner or Merent ones. In the situation of male: female ratio of 1 :5, each mating lasted an average of 6.6 min, with a mean interval between matings at 2.5 min., compared to 11. 1 min and 12.1 min respectively in a cell with 5 males and 1 female. As many as 48 mating events were observed for one male during an 8 h period. One female mated 27 times in 7 h with 5 males in the same cell. Newly emerged males and females can not mate before blood meal and about 24 h blood feeding is rewuired for successful mating. Newly emerged males can not mate with fed females (fed for 48 h), but fed males can mate with newly emerged females who are feeding the blood. Significantly more male contacts and male-male mating attempts were observed after the paper treated with female extract was introduced into the cell. The paper contacts and mating attempts were 16.75–32.25 times and 15.75–31.38 times, respectively, on average during a period of 20 min when different doses (FE) of extract were provided.     

Effects of reducing sample size on density estimates of citrus rust mite (Acari: Eriophyidae) on citrus fruit: simulated sampling

The consequence of reducing sample size on the accuracy and precision of estimates of citrus rust mite, Phyllocoptruta oleivora (Ashmead), densities on oranges was investigated. The sample unit was a 1-cm2 surface area on fruit. Sampling plans consisting of 360, 300, 200, 160, 80, 48, 36, or 20 samples per 4 ha were evaluated through computer simulations by using real count data from 32 data sets of 600 sample units per 4 ha. The original and reduced sampling plans were hierarchical with different numbers of sample areas per 4 ha, trees per area, fruit per tree, and samples per fruit. Individual estimates (n=100 simulations per data set) using each plan were sometimes considerably below or above target densities. In an original set of count data with a mean of six mites per cm2, simulations of 36 samples per 4 ha produced individual estimates ranging from one to 16 mites per cm2, whereas 80 samples per 4 ha produced estimates ranging from two to 10 mites per cm2. The plans consisting of 36 or more samples were projected to provide precision levels of 0.25 (SEM/mean) or better at densities of five or more mites per cm2 based on log-data, a projection that needs to be verified under real-grove situations. Each plan consistently provided mite detection in these sampling simulations except those consisting of 20 or 36 samples, which sometimes failed to detect mites when the target density was less than five mites per cm2. The study provided insight into the probable precision, accuracy and detection thresholds for eight candidate sampling plans varying from relatively low to high resource input.     

Biology of three species of Agistemus (Acari: Stigmaeidae): life table parameters using eggs of Panonychus citri or pollen of Malephora crocea as food

The biology and life table parameters of Agistemus industani Gonzalez, A. cyprius Gonzalez, and A. floridanus Gonzalez (Acari: Stigmaeidae) were studied under laboratory conditions using two food sources: Panonychus citri (McGregor) eggs or ice plant, Malephora crocea (Jacquin) Schwantes pollen at 25 degrees C. The larval, protonymph, deutonymph, and adult stages of A. industani fed on citrus red mite eggs. All active stages of A. industani, except the larva, fed on all P. citri stages and the larval stage could not feed on P. citri adults. All immature stages of A. industani fed on M. crocea pollen. Agistemus cyprius larvae fed on P. citri eggs and larvae or ice plant pollen. The nymphal stages fed on P. citri eggs, larvae, and protonymphs but not deutonymphs or adults while A. cyprius deutonymphs and adults fed on all P. citri stages. Adult and nymphal stages of A. cyprius fed on ice plant pollen and successfully completed their development while A. floridanus did not. Agistemus floridanus larvae fed only on P. citri eggs, while the other stages fed on P. citri eggs, larvae, and protonymphs. The developmental times from egg to adult for A. industani and A. cyprius when fed M. crocea pollen were 11.3 and 13.4 days, respectively. Agistemus floridanus was unable to complete its life cycle on a diet of only M. crocea pollen. Agistemus industani, A. cyprius, and A. floridanus completed development from egg to adult in 11.7, 13.8, and 10.8 days, respectively, when fed P. citri eggs. The intrinsic rate of increase (r(m)) values for A. cyprius and A. industani were 0.0311 and 0.1201 per day on the pollen diet. The net reproductive rate (Ro) was 3.58 for A. cyprius and 10.07 for A. industani with generation times (T) of 45.2 and 35.1 days, respectively, on the ice plant pollen diet. The r(m) values for A. cyprius, A. floridanus, and A. industani on the P. citri egg only diet were: 0.0562, 0.1001, and 0.1031 per day, respectively. The Ro values for each species fed P. citri eggs only were: 6.36, 7.90, and 18.70 for A. cyprius, A. floridanus, and A. industani and the generation times (T) for each of the three species were: 35.2, 29.9 and 37.8 days, respectively.     

Mitochondrial DNA and RAPD polymorphisms in the haploid mite Brevipalpus phoenicis (Acari: Tenuipalpidae)

Brevipalpus phoenicis (Geijskes) (Acari: Tenuipalpidae) is recognized as the vector of citrus leprosis virus that is a significant problem in several South American countries. Citrus leprosis has been reported from Florida in the past but no longer occurs on citrus in North America. The disease was recently reported in Central America, suggesting that B. phoenicis constitutes a potential threat to the citrus industries of North America and the Caribbean. Besides B. phoenicis, B. obovatus Donnadieu, and B. californicus (Banks) have been incriminated as vectors of citrus leprosis virus and each species has hundreds of host plants. In this study, Brevipalpus mite specimens were collected from different plants, especially citrus, in the States of Florida (USA) and São Paulo (Brazil), and reared on citrus fruit under standard laboratory conditions. Mites were taken from these colonies for DNA extraction and for morphological species identification. One hundred and two Random Amplified Polymorphic DNA (RAPD) markers were scored along with amplification and sequencing of a mitochondrial cytochrome oxidase subunit I gene fragment (374 bp). Variability among the colonies was detected with consistent congruence between both molecular data sets. The mites from the Florida and Brazilian colonies were morphologically identified as belonging to B. phoenicis, and comprise a monophyletic group. These colonies could be further diagnosed and subdivided geographically by mitochondrial DNA analysis.     

Effect of switch trimming on udder and teat hygiene of dairy cows

The study objective was to determine the effects of trimming the switch of dairy cows on teat-end bacterial counts and udder hygiene scores. Cows (n = 102) were blocked by days in milk, milk production, and parity and then assigned to (a) treatment (trimming of their tail switch using a commercially available trimmer), or (b) control (unaltered tails). Udder hygiene was recorded for cows on Days 0 (initiation of treatment), 32, and 64. A subset of cows (n = 21) was used to assess Streptococci and coliform bacterial populations on teat ends. Samples were collected by swabbing the left front teat end before milking on Days 0, 32, and 64 and were cultured within 24 hr of sampling. The GLIMMIX and PROC Frequency (SAS Version 9.3) were used to analyze data. There were no treatment effects of switch trimming on hygiene scores or bacterial counts. These findings suggest that udder hygiene may not be driven by tail status. Environmental and management factors, such as cleanliness, stall bedding, and stall design, may be more important contributing factors in maintaining udder health.     

Characterization and Regulation of Sulfur Reductase Activity in Thermotoga neapolitana

The growth of the hyperthermophilic, anaerobic bacterium Thermotoga neapolitana is stimulated by elemental sulfur by an unknown mechanism. We detected hydrogen-dependent sulfur reductase (sulfhydrogenase) and polysulfide dehydrogenase activities in cell extracts of this organism, demonstrating that it has at least two pathways for sulfidogenesis. Hydrogen-dependent sulfur reductase and hydrogenase activities are catalyzed by the purified hydrogenase of Thermotoga maritima, and this enzyme was called the sulfhydrogenase (K. Ma, R. N. Schicho, R. M. Kelly, and M. W. W. Adams, Proc. Natl. Acad. Sci. USA 90:5341-5344, 1993). Cells grown without elemental sulfur or cystine had 1.3 to 3.3 times higher sulfhydrogenase activities than those grown with either of these sources of sulfane sulfur. Hydrogenase activity was 2 to 5 times higher. Polysulfide dehydrogenase was up to 48-fold more active in cell extracts than the sulfhydrogenase. The activity of polysulfide dehydrogenase was approximately twofold higher when cells were grown in the presence of elemental sulfur. Its activity was oxygen labile in crude extracts, and it appears to be a cytoplasmic enzyme. Polysulfide was preferred over elemental sulfur as an electron acceptor (K_m = 0.15 mM) and was more active with NADH (K_m = 0.03 mM) than NADPH (K_m = 0.41 mM). Growth in the presence of elemental sulfur appeared to slightly increase the activity of polysulfide dehydrogenase and slightly decrease both activities of sulfhydrogenase (hydrogenase and polysulfide reductase), while growth without elemental sulfur had the opposite effects. The greater activity of polysulfide dehydrogenase and its apparent regulation indicate that it is the more physiologically important means of polysulfide reduction.