The role of relatedness in structuring the social network of a wild guppy population.

The role of relatedness in structuring animal societies has attracted considerable interest. Whilst a significant number of studies have documented kin recognition in shoaling fish under laboratory conditions, there is little evidence that relatedness plays a significant role in structuring social interactions in wild populations that are characterised by fission-fusion dynamics. Previous work has tended to compare relatedness within and among entire shoals. Such an approach however, does not have the ability to detect social sub-structuring within groups, which appears to be a major factor driving the social organisation of fission-fusion animal societies. Here, we use social network analysis combined with DNA microsatellite genotyping to examine the role of relatedness in structuring social relationships in a wild population of guppies (Poecilia reticulata). Consistent with previous findings, female-female dyads formed the strongest social relationships, which were stable over time. Interestingly, we also observed significant co-occurrence of male-male interactions, which is in contrast to previous work. Although we observed social sub-structuring in the population, we found no evidence for relatedness playing a significant role in underpinning this structure. Indeed, only seven first-degree relative dyads were identified among the 180 fish genotyped, indicating that the majority of individuals do not have a first-degree relative in the population. The high genetic diversity observed in this population is indicative of a large effective population size typical of lowland guppy populations. We discuss our findings in the context of the evolution of social organisation and the mechanisms and constraints that may drive the observed patterns in wild populations.

New Trypanosoma (Duttonella) vivax genotypes from tsetse flies in East Africa.

Salivarian trypanosomes pose a substantial threat to livestock, but their full diversity is not known. To survey trypanosomes carried by tsetse in Tanzania, DNA samples from infected proboscides of Glossina pallidipes and G. swynnertoni were identified using fluorescent fragment length barcoding (FFLB), which discriminates species by size polymorphisms in multiple regions of the ribosomal RNA locus. FFLB identified the trypanosomes in 65 of 105 (61.9%) infected proboscides, revealing 9 mixed infections. Of 7 different FFLB profiles, 2 were similar but not identical to reference West African Trypanosoma vivax; 5 other profiles belonged to known species also identified in fly midguts. Phylogenetic analysis of the glycosomal glyceraldehyde phosphate dehydrogenase gene revealed that the Tanzanian T. vivax samples fell into 2 distinct groups, both outside the main clade of African and South American T. vivax. These new T. vivax genotypes were common and widespread in tsetse in Tanzania. The T. brucei-like trypanosome previously described from tsetse midguts was also found in 2 proboscides, demonstrating a salivarian transmission route. Investigation of mammalian host range and pathogenicity will reveal the importance of these new trypanosomes for the epidemiology and control of animal trypanosomiasis in East Africa.

Phylogenetic analysis reveals the presence of the Trypanosoma cruzi clade in African terrestrial mammals.

Despite the impact of some trypanosome species on human and livestock health, the full diversity of trypanosomes in Africa is poorly understood. A recent study examined the prevalence of trypanosomes among a wide variety of wild vertebrates in Cameroon using species-specific PCR tests, but six trypanosome isolates remained unidentified. Here they have been re-examined using fluorescent fragment length barcoding (FFLB) and phylogenetic analysis of glycosomal glyceraldehyde phosphate dehydrogenase gGAPDH and 18S ribosomal RNA (rDNA) genes. Isolates from a monkey (Cercopithecus nictitans) and a palm civet (Nandinia binotata) belonged to the Trypanosoma cruzi clade, known previously only from New World and Australian terrestrial mammals, and bats from Africa, Europe and South America. Of the four other isolates, three from antelope were identified as Trypanosoma theileri, and one from a crocodile as T. grayi. This is the first report of trypanosomes of the T. cruzi clade in African terrestrial mammals and expands the clade's known global distribution in terrestrial mammals. Previously it has been hypothesized that African and New World trypanosomes diverged after continental separation, dating the divergence to around 100 million years ago. The new evidence instead suggests that intercontinental transfer occurred well after this, possibly via bats or rodents, allowing these trypanosomes to establish and evolve in African terrestrial mammals, and questioning the validity of calibrating trypanosome molecular trees using continental separation.

Organic compounds in lunar samples: pyrolysis products, hydrocarbons, amino acids.

Lunar fines and a chip from inside a rock pyrolyzed in helium at 700 degrees C gave methane, other gases, and aromatic hydrocarbons. Benzene/methanol extracts of fines yielded traces of high molecular weight alkanes and sulfur. Traces of glycine, alanine, ethanolamine, and urea were found in aqueous extracts. Biological controls and a terrestrial rock, dunite, subjected to exhaust from the lunar module descent engine showed a different amino acid distribution. Interpretation of the origin of the carbon compounds requires extreme care, because of possible contamination acquired during initial sample processing.

Genetic variation in strains of zebrafish (Danio rerio) and the implications for ecotoxicology studies.

There is substantial evidence that genetic variation, at both the level of the individual and population, has a significant effect on behaviour, fitness and response to toxicants. Using DNA microsatellites, we examined the genetic variation in samples of several commonly used laboratory strains of zebrafish, Danio rerio, a model species in toxicological studies. We compared the genetic variation to that found in a sample of wild fish from Bangladesh. Our findings show that the wild fish were significantly more variable than the laboratory strains for several measures of genetic variability, including allelic richness and expected heterozygosity. This lack of variation should be given due consideration for any study which attempts to extrapolate the results of ecotoxicological laboratory tests to wild populations.

The identification, diversity and prevalence of trypanosomes in field caught tsetse in Tanzania using ITS-1 primers and fluorescent fragment length barcoding.

We report on the development of two generic, PCR-based methods, which replace the multiple species-specific PCR tests used previously to identify the trypanosome species carried by individual tsetse flies. The first method is based on interspecies size variation in the PCR product of the ITS-1 region of the ribosomal RNA (rRNA) locus. In the second approach, length variation of multiple fragments within the 18S and 28S rRNA genes is assayed by PCR amplification with fluorescent primers; products are subsequently sized accurately and rapidly by the use of an automated DNA sequencer. Both methods were used to identify samples collected during large-scale field studies of trypanosome-infected tsetse in Tanzania in the National Parks of Tarangire and Serengeti, and the coastal forest reserve of Msubugwe. The fluctuations of trypanosome prevalence over time and two different field seasons are discussed. As well as facilitating the identification of trypanosome species with increased speed, precision and sensitivity, these generic systems have enabled us to identify two new species of trypanosome.

A novel, high-throughput technique for species identification reveals a new species of tsetse-transmitted trypanosome related to the Trypanosoma brucei subgenus, Trypanozoon.

We describe a novel method of species identification, fluorescent fragment length barcoding, based on length variation in regions of the 18S and 28Salpha ribosomal DNA. Fluorescently tagged primers, designed in conserved regions of the 18S and 28Salpha ribosomal DNA, were used to amplify fragments with inter-species size variation, and sizes determined accurately using an automated DNA sequencer. By using multiple regions and different fluorochromes, a barcode unique to each species was generated. The technique was developed for the identification of African tsetse-transmitted trypanosomes and validated using DNA from laboratory isolates representing known species, subspecies and subgroups. To test the methodology, we examined 91 trypanosome samples from infected tsetse fly midguts from Tanzania, most of which had already been identified by species-specific and generic PCR tests. Identifications were mainly in agreement, but the presence of an unknown trypanosome in several samples was revealed by its unique barcode. Phylogenetic analyses based on 18S rDNA and glycosomal glyceraldehyde phosphate dehydrogenase gene sequences confirmed that this trypanosome is a new species and it is within the Trypanosoma brucei clade, as a sister group of subgenus Trypanozoon. The overall identification rate of trypanosome-infected midgut samples increased from 78 to 96% using FFLB instead of currently available PCR tests. This was due to the high sensitivity of FFLB as well as its capacity to identify previously unrecognised species. FFLB also allowed the identification of multiple species in mixed infections. The method enabled high-throughput and accurate species identification and should be applicable to any group of organisms where there is length variation in regions of rDNA.

Remarkable richness of trypanosomes in tsetse flies (Glossina morsitans morsitans and Glossina pallidipes) from the Gorongosa National Park and Niassa National Reserve of Mozambique revealed by fluorescent fragment length barcoding (FFLB).

Trypanosomes of African wild ungulates transmitted by tsetse flies can cause human and livestock diseases. However, trypanosome diversity in wild tsetse flies remains greatly underestimated. We employed FFLB (fluorescent fragment length barcoding) for surveys of trypanosomes in tsetse flies (3086) from the Gorongosa National Park (GNP) and Niassa National Reserve (NNR) in Mozambique (MZ), identified as Glossina morsitans morsitans (GNP/NNR=77.6%/90.5%) and Glossina pallidipes (22.4%/9.5%). Trypanosomes were microscopically detected in 8.3% of tsetse guts. FFLB of gut samples revealed (GNP/NNR): Trypanosoma congolense of Savannah (27%/63%), Kilifi (16.7%/29.7%) and Forest (1.0%/0.3%) genetic groups; T. simiae Tsavo (36.5%/6.1%); T. simiae (22.2%/17.7%); T. godfreyi (18.2%/7.0%); subgenus Trypanozoon (20.2%/25.7%); T. vivax/T. vivax-like (1.5%/5.2%); T. suis/T. suis-like (9.4%/11.9%). Tsetse proboscises exhibited similar species composition, but most prevalent species were (GNP/NNR): T. simiae (21.9%/28%), T. b. brucei (19.2%/31.7%), and T. vivax/T. vivax-like (19.2%/28.6%). Flies harboring mixtures of trypanosomes were common (~ 64%), and combinations of more than four trypanosomes were especially abundant in the pristine NNR. The non-pathogenic T. theileri was found in 2.5% while FFLB profiles of unknown species were detected in 19% of flies examined. This is the first report on molecular diversity of tsetse flies and their trypanosomes in MZ; all trypanosomes pathogenic for ungulates were detected, but no human pathogens were detected. Overall, two species of tsetse flies harbor 12 species/genotypes of trypanosomes. This notable species richness was likely uncovered because flies were captured in wildlife reserves and surveyed using the method of FFLB able to identify, with high sensitivity and accuracy, known and novel trypanosomes. Our findings importantly improve the knowledge on trypanosome diversity in tsetse flies, revealed the greatest species richness so far reported in tsetse fly of any African country, and indicate the existence of a hidden trypanosome diversity to be discovered in African wildlife protected areas.

A new lineage of trypanosomes from Australian vertebrates and terrestrial bloodsucking leeches (Haemadipsidae).

Little is known about the trypanosomes of indigenous Australian vertebrates and their vectors. We surveyed a range of vertebrates and blood-feeding invertebrates for trypanosomes by parasitological and PCR-based methods using primers specific to the small subunit ribosomal RNA (SSU rRNA) gene of genus Trypanosoma. Trypanosome isolates were obtained in culture from two common wombats, one swamp wallaby and an Australian bird (Strepera sp.). By PCR, blood samples from three wombats, one brush-tailed wallaby, three platypuses and a frog were positive for trypanosome DNA. All the blood-sucking invertebrates screened were negative for trypanosomes both by microscopy and PCR, except for specimens of terrestrial leeches (Haemadipsidae). Of the latter, two Micobdella sp. specimens from Victoria and 18 Philaemon sp. specimens from Queensland were positive by PCR. Four Haemadipsa zeylanica specimens from Sri Lanka and three Leiobdella jawarerensis specimens from Papua New Guinea were also PCR positive for trypanosome DNA. We sequenced the SSU rRNA and glycosomal glyceraldehyde phosphate dehydrogenase (gGAPDH) genes in order to determine the phylogenetic positions of the new vertebrate and terrestrial leech trypanosomes. In trees based on these genes, Australian vertebrate trypanosomes fell in several distinct clades, for the most part being more closely related to trypanosomes outside Australia than to each other. Two previously undescribed wallaby trypanosomes fell in a clade with Trypanosoma theileri, the cosmopolitan bovid trypanosome, and Trypanosoma cyclops from a Malaysian primate. The terrestrial leech trypanosomes were closely related to the wallaby trypanosomes, T. cyclops and a trypanosome from an Australian frog. We suggest that haemadipsid leeches may be significant and widespread vectors of trypanosomes in Australia and Asia.

Induced systemic candidiasis in young broiler chickens.

Systemic candidiasis was induced in broiler chickens 14 days old by intravenous injection of a suspension of viable Candida albicans cells. Injection resulted in decreased body weight, moderate mortality, swollen and reddened livers and kidneys, pancreatitis, and disturbances of the nervous system. Three types of neutral disturbances were observed: 1) extreme opisthotonus with spasmodic tremors; 2) extreme torticollis with cranial rotation of 270 degrees: and 3) extreme torticolis which resulted in the head being drawn in a medial-ventral direction. None to 50% of the inoculated birds exhibited these neural disturbances, depending on the isolant of C. albicans used. Microbiological examination of internal organs and blood revealed that C. albicans localized in the meninges of the brain. There was also a significant isolant-related effect of C. albicans on the growth rate of the inoculated birds. These easily quantitated differential effects of various isolants of C. albicans offer the prospect of correlating biochemical characteristics with virulence and obtaining information about the mechanism of pathogenicity of this microorganism.

The impact of atrazine on lake periphyton communities, including carbon uptake dynamics using track autoradiography.

Chlorophyll a, freshweight biomass, ash-free dry weight, cell numbers, species richness, community carbon uptake and species-specific carbon uptake were used to monitor the impact of atrazine (2 chloro-4-ethylamino-6-isopropylamino-s-triazine) on an in situ, enclosed periphyton community. Atrazine concentrations ranging from 0.08 to 1.56 mg litre(-1) were used during the 2 years of study. In both 1982 and 1983, there was a shift from a chlorophyte- to a diatom-dominated community. In 1982 the cyanobacterium Cylindrospermum stagnale and the chlorophyte Tetraspora cylindrica developed isolated colonies in the 1.56 mg litre(-1) treatment, indicating resistance to atrazine at this concentration. After atrazine exposure, community productivity was reduced by 21% to 82% in the low to high exposures, respectively. After day 21 productivity returned to control levels. It was shown, using track autoradiography, that the productivities of the larger algae Mougeotia sp., Oedogonium sp., Tolypothrix limbata and Epithemia turgida were the most affected, with reductions of 74.3% to 93.1% that of the controls. All the biotic measures indicated reduced growth after herbicide exposure.

The effect of two applications of atrazine on the water quality of freshwater enclosures.

To simulate runoff from agricultural lands, atrazine was applied to aquatic enclosures (112 m(3)) on 1 June 1983 at a concentration of 0.1 mg litre(-1). Thirty-five days later the nominal concentration was increased to 0.155 mg litre(-1). Treated enclosures became clearer with Secchi disc readings of 3.6 m compared to non-treated controls (2.9 m). Less than 5% of the first atrazine addition disappeared during the first 35 days and little effect on biological activity was observed. However, with the second enrichment the rate of loss of atrazine was rapid (t(1/2) = 150 days), ammonium, calcium, dissolved inorganic carbon and nitrate levels were higher, while oxygen, chlorophyll, dissolved organic carbon and particulate organic carbon concentrations were lower in the treated enclosures. These water quality changes cannot be explained by herbicide-water chemistry interactions alone, thereby suggesting an indirect effect as a consequence of atrazine inhibition on photosynthesis and possibly other microbial processes.

The use of high-performance liquid chromatography for studying pigmentation.

The use of HPLC has established that chickens possess unexpected metabolic abilities to acylate, deacylate, reduce, and oxidize carotenoids. The use of HPLC permits more consistent and more economic pigmentation of carcasses and of egg yolks. Hopefully, the use of HPLC will raise pigmentation from an art to a science. Apparently, HPLC will be an essential tool in terms of future efforts to understand and master the process of poultry pigmentation.

Proof of mycotoxicoses being a field problem and a simple method for their control.

A field trial in which moldy caked feed was removed from the feed delivery truck, storage bins, conveyors, and feeding troughs by scrubbing and disinfecting resulted in improved body weight, pigmentation, and carcass grade of broiler chickens. This improvement which occurred despite the presence of only small and infrequent quantities of aflatoxin and ochratoxin suggest that mycotoxicoses, as yet undefined, can have a deleterious economic effect and further suggests that the mycotoxicoses can be partially controlled by simple preventive measures.

Metabolism of lutein diester during aflatoxicosis in young chickens.

Young chickens were fed from hatching until 3 wk of age with a white corn-soy diet amended with lutein diester to supply 25 micrograms lutein/g diet and with varying amounts of aflatoxin (0, 1, 2, 4, and 8 micrograms/g diet). The lutein diester was added as a stabilized, microencapsulated extract of marigold (Tagetes erecta) petals. Aflatoxin had no significant effect on the partial conversion of lutein diester to lutein monoester and lutein that occurs in the jejunum of normal chickens. The concentration of lutein in the jejunal mucosa was increased slightly by intermediate levels of aflatoxin and depressed by higher levels. Aflatoxin depressed lutein (the dominant form) in serum by up to 40%. Aflatoxin enhanced the lutein accumulation in the liver as the monoester (four-fold) and diester (12-fold). Only minor effects of aflatoxin on the carotenoid content of the toe webs were noted in birds fed lutein diester. These results imply that the main effects of aflatoxin on the utilization of lutein diester are to impair the absorption of lutein, which is an intestinal product of dietary lutein diester, and to sequester lutein as lutein monoester and lutein diester in the liver.

Enhanced production of pancreatic digestive enzymes during aflatoxicosis in egg-type chickens.

As aflatoxin causes malabsorption and its toxicity is enhanced by a low protein diet, digestive enzymes formed in the pancreas apparently are influenced by aflatoxin. This hypothesis was investigated in a 2 X 2 factorial experiment. Six groups of 10 egg-type chickens per treatment were analyzed for the absence and presence of aflatoxin (0 and 4 micrograms/g diet) and for normal (12.75%) and low (10.00%) protein in soy-dextrose diets. The specific activities of pancreatic chymotrypsin, amylase, and lipase, but not trypsin, were increased significantly (P less than .01) by aflatoxin. Lowering dietary protein had no effect by itself except to increase amylase activity. Low protein and aflatoxin interacted to lessen but not prevent the effect of aflatoxin on chymotrypsin and amylase. Calculation of total pancreatic activities revealed that aflatoxin increased trypsin, chymotrypsin, amylase, and lipase to 107, 169, 113, and 119%, respectively, of control values on the low protein diet, whereas values were 99, 175, 115, and 115%, respectively, on the normal protein diet. Neither aflatoxin nor low protein altered significantly (P less than .05) the lipid content of fecal material. Thus, aflatoxicosis in egg-type chickens is characterized by a surplus of some digestive enzymes and by normal fecal lipids in contrast to the specific deficiency of amylase and lipase and steatorrhea reported earlier in meat-type chickens. Whereas malabsorption caused by aflatoxin in broilers can be accounted for in part by impaired digestion, this mechanism apparently does not occur in egg-type chickens.

Factors influencing antifungal activity of gentian violet in poultry feed and ingredients.

The inhibition of fungal activity in poultry feed and ingredients by gentian violet was investigated by measuring respiratory CO2 liberated into the headspace gas above samples of feed and ingredients. Inhibition by gentian violet depended on 1) the lot of corn meal, 2) the concentration of gentian violet, 3) the moisture of the substrate, 4) time of incubation, 5) particle sizes of corn meal and gentian violet, and 6) temperature of a short heating episode mimicking the feed-pelleting process. These same factors were reported earlier to control and limit the activity of organic acid mold inhibitors. These results imply that differences between gentian violet and other mold inhibitors used in poultry feed are quantitative rather than qualitative.

Effect of dietary lipid on lutein metabolism during aflatoxicosis in young broiler chickens.

The effect of concentration of dietary fat on pigmentation of broiler chickens was investigated in diets containing: 1) 0 or 1.4 micrograms of aflatoxin and 35 micrograms of lutein/kcal of diet; and 2) different levels of dietary fat (0, 2, 4, 6, 8, or 10% cottonseed oil). Serum lutein and its metabolite, 3'-oxolutein, increased with increasing dietary fat until it reached a plateau at 6% fat. Aflatoxin significantly (P less than .05) lowered serum lutein and 3'-oxolutein at all levels of fat. Dietary fat and aflatoxin interacted significantly (P less than .05), with the effect of aflatoxin being greater at the low levels of fat than at the high fat levels. In the toe webs of the birds, the concentrations of lutein and its metabolites, lutein monoester, lutein diester, and 3'-oxolutein responded similarly to aflatoxin and to dietary fat, except that increasing the amount of dietary fat did not spare the effect of aflatoxin on 3'-oxolutein. The effect of chain length and the saturation of fatty acids on the absorption of lutein during aflatoxicosis was investigated in a factorial design for aflatoxin (0 and 4 micrograms/g of diet) and seven fatty acids at 5% of the diet. In control birds, lutein absorption was promoted by lauric = oleic greater than capric = linoleic greater than myristic greater than palmitic = stearic acids. Aflatoxin significantly (P less than .05) depressed the absorption of lutein regardless of the fatty acid present.(ABSTRACT TRUNCATED AT 250 WORDS)