Comparison of genetic diversity at microsatellite loci and quantitative traits in hatchery populations of Japanese flounder Paralichthys olivaceus

Relationships of genetic diversity at microsatellite loci and quantitative traits were examined in hatchery-produced populations of Japanese flounder using a relatively straightforward experiment. Five hatchery populations produced by wild-caught and domesticated broodstocks were used to examine the effects of different levels (one to three generations) of domestication on the genetic characteristics of hatchery populations. Allelic richness at seven microsatellite loci in all hatchery populations was lower than that in a wild population. Genetic variation measured by allelic richness and heterozygosity tended to decrease with an increase in generations of domestication. In addition, the degree of genetic differentiation from a wild population increased with an increase in generations of domestication. Significant differences in three morphometric traits (dorsal and anal fin ray counts and vertebral counts) and three physiological traits (high temperature, salinity and formalin tolerance) were observed among the hatchery populations. The degree of phenotypic difference among populations was larger in morphometric traits than in physiological traits. The divergence pattern of some quantitative traits was similar to that observed at microsatellite loci, suggesting that domestication causes the decrease of genetic variation and the increase of genetic differentiation for some quantitative traits concomitantly with those for microsatellite loci. Significant positive correlation was observed between F _ST and the degree of phenotypic difference in the three morphometric traits and formalin tolerance, indicating that genetic variation at microsatellite loci predicts the degree of phenotypic divergence in some quantitative traits.     

Variation in modern human premolar enamel formation times: implications for Neandertals

A recent study demonstrated that variation in enamel cap crown formation in the anterior teeth is greater than that in the molars from two geographically distinct populations: native indigenous southern Africans and northern Europeans. Eighty southern African and 69 northern European premolars (P3 and P4) were analyzed in the present study. Cuspal, lateral, and total enamel formation times were assessed. Although cuspal enamel formation times were not consistently different between the two populations, both lateral and total enamel formation times generally were. Bonferroni-corrected t-tests showed that southern Africans had significantly shorter lateral enamel formation time for five of the six cusps, as well as significantly shorter total enamel formation time for these same cusps. An analysis of covariance performed on the lingual cusps of the upper third and fourth premolars showed that differences in enamel formation times between these populations remained when crown height was statistically controlled. A further goal of this study was to ascertain, based on perikymata counts, what Neandertal periodicities would have to be in order for their teeth to have lateral enamel formation times equivalent to either southern Africans or northern Europeans. To this end, perikymata were counted on 32 Neandertal premolars, and the counts were inserted into regression formulae relating perikymata counts to periodicity for each population and each tooth type. Neandertal enamel formation times could be equivalent to those of southern Africans or northern Europeans only if their hypothetical periodicities fall within the range of periodicities for African apes and modern humans (i.e., 6-12 days). The analysis revealed that both populations could encompass Neandertal timings, with hypothetical periodicities based on the southern African population necessitating a lower range of periodicity (6-8 days) than those based on the northern European population (8-11 days).     

Digital dermatoglyphics of Bulgarians from northeast Bulgaria

Digital dermatoglyphics were collected from 1,065 male and 1,065 female Bulgarians from northeast Bulgaria. None of the subjects had a diagnosed or suspected genetic or chronic disease of any kind. The fingerprints were classified by the 18-type system of Monique de Lestrange, modified to provide rapid and easy comparison with simpler classification systems. All the standard finger pattern indices were calculated. Certain modifications were introduced into the delta indices, it being borne in mind that each tented arch possesses a triradius and each complex (three-centered, accidental) whorl contains three triradii. A deltadiagram was constructed and its configuration was compared with those of some other populations. In addition, a new radioulnar index was proposed, representing a ratio between all the radial and all the ulnar patterns. The total, absolute, ulnar and radial finger ridge counts were calculated and their sample distributions were investigated. The dermatoglyphic features were evaluated and presented for each sex and each hand separately in order to investigate both the sex and bilateral differences. The set of data presented in this paper is a component of the physical anthropology of the general Bulgarian population. At the same time these data can be used as controls when analyzing the dermatoglyphic findings in Bulgarian patients with genetic diseases or congenital malformations.     

Quantitative finger dermatoglyphics in a Spanish population (Tierra de Campos)

This study deals with the finger ridge counts and the distribution of their frequencies drawn from a Spanish sample consisting of 833 school-children (417 males and 416 females), which has been collected from the geographical area of Tierra de Campos. Paired t-test and Student-t-test were used to explore bimanual and sexual differences, respectively. The results showed: a bimanual asymmetry marked by significantly higher right hand ridge count for thumb and index pairs in both males and females, ridge counts of males are always higher than the corresponding values of females; the differences being significant excepting for right and left index and for left ring-finger. The frequency distribution of TFRC was slightly, but significantly, different from normality only in males, as Kolmogorov test showed. A great homogeneity between values for TFRC of males and females from Tierra de Campos and those of the available Spanish and Portuguese populations has been found, the values being high not only in the variation ranges of the Spanish and Portuguese populations, but also in the ranges reported for other European populations.     

WIREWORM POPULATIONS IN RELATION TO CROP PRODUCTION: II. POPULATION CHANGES IN GRASSLAND

Six grass fields were sampled once a fortnight from July 1943 to September 1944, and the wireworms in the samples counted by the washing and flotation method.
The counts from twenty standard samples showed huge fluctuations which rendered them practically valueless as estimates of wireworm populations when treated singly. When treated as running means of four consecutive samplings, the counts showed certain seasonal trends, with minimum populations in July and August, rising populations throughout the autumn, maximum populations in the months from January to April and a sharp decline to the minimum populations again from April to July. On the average, the counts taken in winter were twice as high as those taken in the summer months.
The fluctuation was evident in all size groups based on larval length but was most marked in the wireworms 'under 4 mm.', '4 mm.' and '5 mm.'
Samples taken to depths of 12 and 24 in. showed that on the average about 75 % of the wireworms were found in the 0–6 in. layer and about 90% in the 0–12 in. layer. These proportions varied considerably with the seasons.
The seasonal changes in wireworm populations observed do not correspond with those expected from the life history of Agriotes spp. Possible explanations for this anomaly are discussed, but it cannot be attributed to any known technical or biological factor. Several possibilities remain to be explored.     

Factors influencing the fecal egg and oocyst counts of parasites of wild European rabbits Oryctolagus cuniculus (L.) in Southern Western Australia

Abundance of intestinal parasites was monitored by fecal egg and oocyst counts for samples of wild rabbits Oryctolagus cuniculus with different levels of imposed female sterility from 12 populations in southwestern Australia. Differences in egg counts of Trichostrongylus retortaeformis between seasons and age groups were dependent on the sex of the host. Pregnancy may have been responsible for these differences because egg counts were consistently higher in intact females than in females surgically sterilized by tubal ligation. Egg counts for Passalurus ambiguus were influenced by season and host age but there were no differences between sexes or between intact and sterilized female rabbits. No differences were detected in the oocyst counts of the 8 species of Eimeria between male and female rabbits or between intact and sterilized females. Seasonal differences were detected in oocyst counts of Eimeria flavescens and Eimeria stiedai. The overwhelming determinant of coccidian oocyst counts was host age, with 6 species being much more abundant in rabbits up to 4 mo of age. There was a suggestion that egg counts of T. retortaeformis and oocyst counts of several species of Eimeria were reduced in populations where rabbit numbers had been depressed for at least 2 yr, but there was no evidence that short-term variations in rabbit numbers had a measurable effect on parasite abundance.     

Evaluation of the association of parasitism with mortality of wild European rabbits Oryctolagus cuniculus (L.) in southwestern Australia

Abundances of the parasitic nematodes Trichostrongylus retortaeformis and Passalurus ambiguus, and 8 Eimeria species were estimated by fecal egg and oocyst output in 12 discrete free-ranging populations of wild rabbits (Oryctolagus cuniculus) in southwestern Australia. Comparisons of parasite egg and oocyst counts were made between those rabbits known to have survived at least 2 mo after fecal samples were collected and those rabbits that did not survive. There were significant negative relationships between parasite egg and oocyst counts and survival when all age groups and collection periods were pooled for several species of coccidia and for T. retortaeformis. However, when the same comparisons were made within rabbit age groups and within collection periods, there were very few significant differences even where sample sizes were quite large. The differences indicated by the pooled analysis for coccidia were most likely due to an uneven host age distribution with respect to survival, combined with an uneven distribution of the oocyst counts with rabbit age. The result for T. retortaeformis was similarly affected but by a seasonal pattern. Parasitism by nematodes and coccidia did not appear to be an important mortality factor in these rabbit populations, at least at the range of host densities we examined. This suggests that other factors must have been responsible for the observed pattern of density-dependent regulation in these rabbits.     

Testing potatoes bred from Solarium vernei for resistance to the white potato cyst-nematode, Heterodera pallida

Three clones of potatoes bred from Solanum vernei were tested for their resistance to the white potato cyst-nematode, Heterodera pallida, both by root-ball counts and by estimates of total cysts produced. Two susceptible clones were used as controls. Root-ball counts suggested a higher degree of resistance than that based on total cysts produced. There were differences in pathogenicity between the two populations. The degree of resistance found was such that in practice the resistant clones would be best used in conjunction with nematicide treatment in a system of integrated control.     

Survey of predators and sampling method comparison in sweet corn

Natural predation is an important component of integrated pest management that is often overlooked because it is difficult to quantify and perceived to be unreliable. To begin incorporating natural predation into sweet corn, Zea mays L., pest management, a predator survey was conducted and then three sampling methods were compared for their ability to accurately monitor the most abundant predators. A predator survey on sweet corn foliage in New York between 1999 and 2001 identified 13 species. Orius insidiosus (Say), Coleomegilla maculata (De Geer), and Harmonia axyridis (Pallas) were the most numerous predators in all years. To determine the best method for sampling adult and immature stages of these predators, comparisons were made among nondestructive field counts, destructive counts, and yellow sticky cards. Field counts were correlated with destructive counts for all populations, but field counts of small insects were biased. Sticky cards underrepresented immature populations. Yellow sticky cards were more attractive to C. maculata adults than H. axyridis adults, especially before pollen shed, making coccinellid population estimates based on sticky cards unreliable. Field counts were the most precise method for monitoring adult and immature stages of the three major predators. Future research on predicting predation of pests in sweet corn should be based on field counts of predators because these counts are accurate, have no associated supply costs, and can be made quickly.     

Resolution of genetic and uterine environmental effects in a family study of new dermatoglyphic measure: sole pattern ridge counts

The heritability of sole pattern ridge counts was examined in two family studies of endogamous castes from peninsular India. The phenotypes included ridge counts for each of the eight configurational areas separately, all areas combined, and only distal areas combined. Differences in heritability estimates were found between populations as well as among the individual configurational areas. Although some ridge counts do not show familial resemblance, others appear to be moderately heritable. Estimates of h2 range from 0.36 to 0.63 in one family series and from 0.22 to 0.51 in the other. In addition, significant uterine environmental effects were detected in one family series but not in the other.     

Seasonal changes in numbers and the location of a particular bacterial strain of Alteromonas sp. in seagrass sediments

Many variables must be considered in seeking to describe differences in population sizes for native aquatic bacterial populations. In this study of seagrass- and nearby plant-free sediments, seasonal effects on total bacterial counts were found to be highly significant, outweighing the significance of factors such as geographic variability, but on populations of a chosen Alteromonas sp., they were not significant at the 5% level. Summer counts for both populations were higher than those for winter; this result is likely to reflect the higher productivity of the host Zostera capricomi in summer months, resulting in the exudation of increased amounts of organic nutrients. The Alteromonas sp. occurred in greatest abundance (1.8% of the total population) at the seagrass sediment site from which it was originally isolated and formed up to 1.5% of the population in adjacent plant-free sediments. In fluorescent microscopy studies with labeled antibodies, the Alteromonas sp. was found to be ubiquitous in seagrass and plant-free sediments but was found closely associated in much higher numbers with seagrass root-rhizome tissue, suggesting a possible nutritional relationship between plant and bacterium. In associated trials of sediment preservation techniques, bacterial counts of replicate sediments preserved with glutaraldehyde (3% v/v) were higher than those obtained using Lugol's iodine or freezing. Correspondence to: P.W. Glazebrook     

Molecular and chromosomal polymorphism in continental and insular populations from the southwestern range of Drosophila subobscura

Eight insular and continental populations from the south-western range of Drosophila subobscura have been studied with regard to molecular and inversion polymorphisms. Heterogeneity between populations with respect to allele frequencies of 4 gene loci (Amy, Est-8, Est-9 and Pep-1) is the highest known for natural populations of the species. Moreover, the most common allele for these loci is not the same in all populations. Cladograms based on UPGMA clustering of the genetic distances based on allele frequency do not coincide with those constructed with inversion data. The allele-frequency differences between the populations may be due to non-random associations between enzyme alleles and gene arrangements and to founder effects appearing in the insular populations.     

Sperm production in an extremophile fish,the cave molly (<Emphasis Type="Italic">Poecilia mexicana</Emphasis>, Poeciliidae,Teleostei)

A prominent trade-off in life history theory and evolution balances the costs of reproduction with those of basic somatic needs. Hence, reproductive efforts may be reduced in environments where additional energy is required for somatic maintenance. Here, we investigated male sperm stores in Atlantic mollies (Poecilia mexicana) from a sulfidic cave and several sulfidic and non-sulfidic surface habitats. We found significant differences among populations in the number of sperm stripped per male, which was also correlated with differences in gonad weights. The largest sperm stores were detected in males from non-sulfidic surface creeks, while males from a partially sulfidic surface system had lower sperm counts, and males from completely sulfidic systems, surface as well as subterranean, had even fewer available sperm. We conclude that the extreme environmental conditions in sulfidic habitats appear to constrain male sperm production, since hydrogen sulfide as a naturally occurring toxin requires energy-demanding adaptations. Furthermore, we examined sperm counts of lab-reared cave and surface mollies in response to energy limitation. Males from stock populations were placed under high and low food treatments for a 2-week period and then stripped of sperm. Sperm counts of surface mollies tended to be reduced by low food availability, whereas sperm counts of cave mollies did not significantly vary between food treatments, which likely points towards a higher starvation resistance in cave mollies.     

Dermatoglyphic variation in Spanish Basque populations

The present study involves the evaluation of digital dermatoglyphic traits of 2185 unrelated individuals (1152 females and 1033 males) from 17 natural valleys of the four Basque provinces (Vizcaya, Guipúzcoa, Navarra, and Alava) in the Spanish Basque Country. Univariate intervalley and between-sex comparisons were carried out by means of chi-square contingency analysis for pattern types and by means of one-way analysis of variance for ridge counts. Multivariate intervalley comparison was carried out by means of correspondence analysis for pattern types and by principal component analysis for ridge counts. The results of this study are notable for the following findings: (1) in general, all variables are significantly heterogeneous among valley populations; (2) there was a greater differentiation among the valley populations than between sexes in one valley population; (3) affinities among the intervalley populations depend on the variables considered; (4) the valley populations from Vizcaya resemble those from the Pyrenees; (5) based on interprovince comparisons, the Vizcaya and Navarra samples are the closest: (6) in general, the valley samples from Alava are the worst clustered; (7) the universality of dermatoglyphic component structure fits better in males.     

Differential carbohydrate media and anaerobic replica plating techniques in delineating carbohydrate-utilizing subgroups in rumen bacterial populations

A basal (BC) medium devoid of added carbohydrates, a complete (CC) medium containing nine carbohydrates were developed for enumerating rumen bacteria. The colony counts on the BC medium were 85 to 100% of those obtained on the CC medium. These colonies were pinpoint size (less than or equal to mm in diameter) but increased in size (2 to 5 mm in diameter) when carbohydrates were subsequently added. With the CC medium or other media tested, the colony counts were 20 to 50% higher on plates than on roll tubes and were about 35% of the direct cell counts. The lower colony counts on roll tubes were shown to result primarily from the loss of viability due to heat stress. The DC media were found by plating techniques to be suitable for differentiating mixed rumen bacterial populations into subgroups based upon carbohydrate utilization as shown by differences in subgroup profiles found within solid and liquid fractions of rumen contents, within rumen contents from animals fed high-forage and high-grain diets, and by correct colony formations by pure cultures of rumen bacteria on appropriate DC media. With simple modifications and use of an anaerobic glove box, replica plating methods and the CC and DC media were found to be a suitable means of rapidly determining the range of utilizable carbohydrate energy sources of rumen bacteria.     

Differential carbohydrate media and anaerobic replica plating techniques in delineating carbohydrate-utilizing subgroups in rumen bacterial populations.

A basal (BC) medium devoid of added carbohydrates, a complete (CC) medium containing nine carbohydrates were developed for enumerating rumen bacteria. The colony counts on the BC medium were 85 to 100% of those obtained on the CC medium. These colonies were pinpoint size (less than or equal to mm in diameter) but increased in size (2 to 5 mm in diameter) when carbohydrates were subsequently added. With the CC medium or other media tested, the colony counts were 20 to 50% higher on plates than on roll tubes and were about 35% of the direct cell counts. The lower colony counts on roll tubes were shown to result primarily from the loss of viability due to heat stress. The DC media were found by plating techniques to be suitable for differentiating mixed rumen bacterial populations into subgroups based upon carbohydrate utilization as shown by differences in subgroup profiles found within solid and liquid fractions of rumen contents, within rumen contents from animals fed high-forage and high-grain diets, and by correct colony formations by pure cultures of rumen bacteria on appropriate DC media. With simple modifications and use of an anaerobic glove box, replica plating methods and the CC and DC media were found to be a suitable means of rapidly determining the range of utilizable carbohydrate energy sources of rumen bacteria.     

Evaluation of Chromocult enterococci agar for the isolation and selective enumeration of Enterococcus spp. in broilers

AIMS: To investigate the productivity and specificity of a new chromogenic enterococci selective medium (Chromocult enterococci agar) recently developed by Merck. METHODS AND RESULTS: The study was carried out comparing Chromocult enterococci agar with MRS agar (Merck), a basal lactic acid bacteria medium in current use. A total of 216 faecal samples from poultry were collected and enterococci populations were counted. Likewise, 100 randomly selected strains were identified for each medium. The differences found between the two media were analysed and discussed. CONCLUSIONS: A good sensitivity of 98% was obtained for Chromocult agar and all false-positive isolates obtained were identified as Leuconostoc spp. However significant differences (P<0.01) were obtained between the enterococci species isolation rates identified from these two media, suggesting the poor growth of some species in Chromocult enterococci agar. Viable counts of Enterococcus spp. obtained with MRS agar were significantly higher than those obtained with Chromocult enterococci agar. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of chromogenic media for microbiological analysis is increasing. Independent studies are important to evaluate newly developed chromogenic media.     

Effects of agronomic treatments on structure and function of ammonia-oxidizing communities

The aim of this study was to determine the effects of different agricultural treatments and plant communities on the diversity of ammonia oxidizer populations in soil. Denaturing gradient gel electrophoresis (DGGE), coupled with specific oligonucleotide probing, was used to analyze 16S rRNA genes of ammonia oxidizers belonging to the beta subgroup of the division Proteobacteria by use of DNA extracted from cultivated, successional, and native deciduous forest soils. Community profiles of the different soil types were compared with nitrification rates and most-probable-number (MPN) counts. Despite significant variation in measured nitrification rates among communities, there were no differences in the DGGE banding profiles of DNAs extracted from these soils. DGGE profiles of DNA extracted from samples of MPN incubations, cultivated at a range of ammonia concentrations, showed the presence of bands not amplified from directly extracted DNA. Nitrosomonas-like bands were seen in the MPN DNA but were not detected in the DNA extracted directly from soils. These bands were detected in some samples taken from MPN incubations carried out with medium containing 1,000 microg of NH(4)(+)-N ml(-1), to the exclusion of bands detected in the native DNA. Cell concentrations of ammonia oxidizers determined by MPN counts were between 10- and 100-fold lower than those determined by competitive PCR (cPCR). Although no differences were seen in ammonia oxidizer MPN counts from the different soil treatments, cPCR revealed higher numbers in fertilized soils. The use of a combination of traditional and molecular methods to investigate the activities and compositions of ammonia oxidizers in soil demonstrates differences in fine-scale compositions among treatments that may be associated with changes in population size and function.     

On the variation in chromosome number in Potamogeton pectinatus L.

To determine whether the large morphological differences that occur between populations of Potamogeton pectinatus L. have a genetic basis, the chromosome numbers of several populations were counted. Although several numbers were determined, no correlation between different numbers and populations could be established. The number was always close to 2n = 78, which is that most recorded for P. pectinatus in the literature. However, although some aberrant counts can probably be ascribed to incorrect interpretations of the preparations, some cells undoubtedly contain more than 78 chromosomes. Since the chromosomes of P. pectinatus are very small it is difficult to distinguish between “normal” and “B-chromosomes”, which may be the cause of the higher numbers.     

Distribution of <Emphasis Type="Italic">HLA-B</Emphasis> alleles in Mexican Amerindian populations

In the present study we analyzed by PCR-SSO technique the HLA-B gene frequencies in 281 healthy individuals from four Mexican Amerindian populations (66 Mayos, 90 Mazatecans, 72 Nahuas and 53 Teenek). The most frequent alleles in all studied populations were HLA-B35, HLA-B39, and HLA-B40; however, some differences were observed between populations. The HLA-B35 allele was the most frequent in three of the four populations studied (Mayos, Nahuas and Teenek), whereas in Mazatecans the most frequent allele was HLA-B39. HLA-B40 presented frequencies higher than 10% in all groups. On the other hand, only Mayos presented an HLA-B51 gene frequency higher than 10%. When comparisons were made, important differences between groups were observed. The Teenek group presented an increased frequency of HLA-B35 when compared to Mazatecans and the HLA-B52 allele was increased in Nahuas and Teenek when compared to Mayos. An increased frequency of HLA-B39 was observed in Mazatecans when compared to Nahuas, Mayos and Teenek. Also, an increased frequency of HLA-B51 was observed in Mayos when compared to Mazatecans and Nahuas. These data corroborate the restricted polymorphism of HLA-B alleles and the high frequency of HLA-B35, HLA-B39 and HLA-B40 alleles in autochthonous American populations. In spite of the restriction in this polymorphism, differences in frequencies of HLA-B alleles could be helpful in distinguishing each of these populations.