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PubMed2003

Genetic diversity and molecular markers of the tropical abalone (Haliotis asinina) in Thailand.

Genetic diversity of abalone in Thailand, Haliotis asinina, H. ovina, and H. varia, was analyzed by polymerase chain reaction (PCR) of 18S and 16S rDNAs, with randomly amplified polymorphic DNA (RAPD) and restriction fragment length polymorphism (RFLP). Species-specific RAPD markers were found in each abalone species. Restriction analysis of 18S (nuclear) ribosomal DNA with Alu I, Taq I, and Hae III and 16S (mitochondrial) rDNA with Bam HI, Eco RI, Hae III, and Alu I gave 12 and 13 digestion patterns, respectively. A total of 49 composite haplotypes were found. A dendogram obtained by the unweighted pair-group method with arithmetic mean, constructed from divergence between pairs of composite haplotypes, revealed reproductively isolated gene pools of these abalone and indicated that H. asinina and H. ovina are genetically closer than H. varia. When H. varia was discovered owing to small sample sizes, geographic heterogeneity analysis and FST estimate indicated clear genetic differentiation between H. ovina originating from the Andaman Sea (west) and the Gulf of Thailand (east, P<0.0001), whereas partial differentiation was observed between the Philippines and the remaining H. asinina samples (P<0.0021). The amplified 16S rDNAs of individuals representing composite haplotypes found in this study were cloned and sequenced. A neighbor-joining tree constructed from sequence divergence of 16S rDNA accurately allocated those sequences according to species origins of abalone. Species-specific PCR based on 16S rDNA polymorphism was successfully developed in H. asinina and H. varia but not in H. ovina.

Animals↗

PubMed2026

Assessment of Genetic Diversity and Population Structure on Azadirachta indica A. Juss. in an Urban Metropolitan: Ahmedabad, India.

Azadirachta indica (A. indica) A. Juss., commonly known as Neem, is a valuable multipurpose tree with profound medicinal properties and socioeconomic importance, widely recognized since ancient Ayurvedic times. Despite its prominence, knowledge about its genetic diversity within the metropolitan area of Ahmedabad is limited. This study marks the first in-depth exploration of the genetic diversity and population structure of A. indica in Ahmedabad. The authenticity of the species was validated through DNA barcoding, and a Geographical Information System (GIS) was used to collect the samples. A total of 35 A. indica accessions were analyzed using five Inter Simple Sequence Repeat (ISSR) primers. Genetic diversity and population structure were evaluated using Inter Simple Sequence Repeat (ISSR) markers through polymorphism assessment, clustering, ordination, and Bayesian population structure analyses. ISSRs revealed a high level of polymorphism (75.66%), indicating substantial genetic variability among accessions. An analysis of genetic diversity indices revealed low to moderate diversity (Hs = 0.14, Ht = 0.217, I = 0.217). Analysis of Molecular Variance (AMOVA) analysis depicted 81% variation within the population and 19% among the population. Low to moderate genetic differentiation (Gst = 0.319) and moderate gene flow (Nm = 1.06) indicated that urban development has not hindered gene flow among populations. Mantel's test revealed a weak but significant correlation between genetic and geographic distances, suggesting limited isolation by distance. The estimated ΔK using STRUCTURE exhibited two subpopulations, representing two gene pools for A. indica accessions (K = 2). Collectively, these patterns indicate that urbanization has not severely disrupted genetic connectivity in A. indica, reflecting its resilience and adaptive potential in a metropolitan environment. These findings provide pivotal knowledge for further understanding the genetic diversity and population structure of A. indica in one of the fastest-growing cities in India, which can be utilized for new breeding programmes, sustainable development and future conservation strategies around the globe.

India↗

PubMed2005

Hybrid disadvantage in the larval foraging behaviour of the two neotropical species of Drosophila pavani and Drosophila gaucha.

Flies from two populations of the Chilean endemic neotropical species Drosophila pavani and two populations of its sibling species Drosophila gaucha were crossed reciprocally to obtain intra- and interspecific hybrids. The developmental pathways of locomotor activity and feeding rate were analysed for eleven of twelve possible genotype groups. The hybrids showed reduced fitness indicated by a decrease in the measured traits. Hybrid disadvantage was strongest in interspecific hybrids, especially with respect to feeding behaviour. This evidence supports the contention that D. pavani and D. gaucha have evolved different coadapted gene pools controlling the developmental pathways for behavioural traits expressed during larval foraging; but genetic divergence affecting these behaviours has also taken place between locally adapted populations within each species.

Animals↗

PubMed2006

Population substructuring in a migratory freshwater fish Prochilodus argenteus (Characiformes, Prochilodontidae) from the São Francisco River.

The construction of hydroelectric dams, pollution of rivers and other environmental changes are responsible for the disappearance of many natural fish stocks. The purpose of this work was to analyze the fish Prochilodus argenteus inhabiting the region of the Três Marias dam in the São Francisco River (Brazil) collected in two sites having distinct environmental characteristics. Three novel homologous and one known cross-specific microsatellites were used to assess genetic variation within and between the two collection sites (namely A and B) in order to confirm the occurrence of population substructuring previously suggested using RAPD markers. A higher number of exclusive alleles and a greater genetic variability in region B strongly reinforce the co-existence of different reproductive units in this area. F(ST) estimates showed a significant population differentiation between the two sites, indicating the possible existence of distinct gene pools. Considering the economic importance of this fishery resource in the São Francisco River, these findings could provide very important information for fisheries management, aquaculture and conservation of the stocks of this species.

Alleles↗

PubMed2006

Population structure of the boll weevil in cotton fields and subtropical forests of South America: a bayesian approach.

The main goal of this contribution is to investigate the genetic structure of boll weevil populations from South America (Argentina and Brazil) and to make further comparisons with a putative source population from USA. Samples were collected in a Paranaense forest under reserve protection, cotton fields and non-cultivated areas. Data from anonymous molecular markers were analysed using both traditional methods of population genetics and Bayesian approaches. Results help to support a previous hypothesis on the presence of two lineages of boll weevil populations in South America: one with characteristics of recent invaders and the other with characteristics of ancient populations. The sample from Urugua-í Provincial Park (Misiones, Argentina) shows the highest percentage of polymorphic loci, the highest values of mean heterozigosity, and the largest number of population-specific alleles, all being typical features of ancient populations. Furthermore, the Urugua-í sample shows two gene pools occurring in sympatry, probably as a consequence of a secondary contact. The remaining samples reveal not only lower percentages of polymorphic loci and heterozygosity values, but also an almost negligible presence of specific alleles. Bayesian methods also suggest the occasional migration of some individuals of ancient lineages from their natural habitats in fragments of the Paranaense forest into cotton fields, and vice versa.

Animals↗

PubMed2005

Management of wild ungulate populations in Italy: captive-breeding, hybridisation and genetic consequences of translocations.

Captive-reproduced stocks of some species of ungulates (Artiodactyla), and particularly the red deer (Cervus elaphus), fallow deer (Dama dama), roe deer (Capreolus capreolus) and the wildboar (Sus scrofa) are more or less extensively translocated in Italy, mainly for local reintroductions or restocking of exploited wild populations. However, captive breeding often involves the reproduction of non-indigenous individuals or the production of artificial hybrids. Consequently, translocations of captive-reproduced ungulates are of concern for the conservation of indigenous populations and gene pools. The impact of translocations should be evaluated within the background of the growing knowledge on population genetic and phylogeographic structure of ungulates. Molecular genetic markers are being used to map geographic genetic diversity, and reconstruct the phylogeographic history of natural populations (i.e., in the roe deer). Molecular makers are also used to detect the consequences of domestication and identify hybrids between wild and domesticated populations (i.e., in the wildboar), or to detect inter-specific hybridisation (i.e., between the red deer and wapiti). Hybridisation of wild and domestic pigs, and diffusion of hybrids in nature is widespread in Italy. Admixture of indigenous and non-indigenous roe deer stocks is also widespread. Therefore, conservation and management of indigenous ungulates calls for careful evaluation of captive-reproduced stocks.

Animals↗

PubMed1983

Two forms of hypertrophic cardiomyopathy distinguished by inheritance of HLA haplotypes and left ventricular outflow tract obstruction.

In this study we have performed human leukocyte antigen (HLA)-A and B typing on nine patients with hypertrophic cardiomyopathy (HCM) and their relatives. Four patients had relatives who also had the disease. HLA typing of the familial form of HCM revealed a very close association of a given HLA-A,B haplotype with the occurrence of the disease. All four patients who had affected relatives had obstruction of left ventricular outflow (LVOT), while four patients with unaffected relatives did not have obstruction. One additional patient with obstruction and without familial incidence was an only child and had few living relatives. Thus, HCM can be divided into two subtypes: a familial form linked to the HLA-A,B system, which may be related to obstructive type, and a sporadic form not linked to HLA antigens. These data confirm the existence of at least two separate forms of hypertrophic cardiomyopathy. The study also confirms their existence in the Japanese population, with a completely different gene pool than the population from the southeastern United States in whom the observation was initially described.

Adolescent↗

PubMed1994

Snake odor alters behavior, but not pain sensitivity in mice.

It is known that predator cues (both mammalian odor or avian vocalization) elicit marked analgesia in rodents. The present experiment used olfactory cues produced by an opportunistic rodent predator snake species (100 cc of sawdust scented by Elaphe quatuorlineata). Upon exposure to snake odor (for 30 s, 20 min, or 40 min), adult mice of both the CD-1 and DBA2 strains were assessed for tail-flick or hot-plate analgesia at different times after exposure (from 0 to 40 or 45 min, respectively). In both strains, snake odor exposure induced significant alteration in the frequencies of sniffing, self-grooming, and digging, while it inhibited habituation of locomotor activity in DBA/2 mice. No analgesia emerged with both tests as a consequence of exposure to snake odor. Results suggest that although endogenous analgesia has been demonstrated by other authors to be elicited in response to cues emanating from common and widely distributed mouse predators (such as carnivores or owls), predators such as reptiles, which under natural conditions exert a limited predatory pressure on the house mouse gene pool, may only induce fear-associated behavioral responses but cannot provide ethologically relevant stimuli triggering mouse analgesia.

Animals↗

PubMed1992

Aging and mortality: manifestations of natural 'non-selection'.

Aging and mortality have long been a source of concern, fascination and investigation. The ultimate question being, why do we age and die? The method of longitudinal Gompertzian analysis demonstrates that aging and mortality are deterministically linked. Moreover, this method of analysis reveals that with enhanced human survival, mortality patterns have changed primarily as the result of the unmasking of latent susceptibilities to other Gompertzian diseases rather than altered environmental etiopathogenic influences. That is, the Gompertzian model of human aging and mortality suggests that redundant programmed failure is the primary reason for ultimate and inevitable mortality. A process by which redundant deterministic disease susceptibilities could accumulate within the genome is natural 'non-selection'. Random genetic mutations which enhance survival until reproduction facilitate the processes of natural selection and evolution. However, random genetic mutations that program for late failure or disease susceptibility would not be eliminated from the gene pool. Thus, random genetic mutations which have programmed for late susceptibility to Gompertzian diseases, and their cumulative non-selection, may be the basis for the deterministic relationship between aging and mortality.

Adult↗

PubMed1995

Increasing multiple myeloma mortality among the elderly: a manifestation of aging and differential survival.

Increasing multiple myeloma incidence and mortality among the elderly in industrialized nations has been attributed to associated environmental carcinogens. Age-specific multiple myeloma mortality rates in the United States from 1968 to 1989 were analyzed using the Strehler-Mildvan modification of the Gompertz relationship between aging and mortality. The results suggest that worsening environmental influences are not responsible for increasing multiple myeloma mortality among the elderly. Differential survival, a concept originally popularized by Charles Darwin, and its effect upon the surviving gene pool in an aging population is an alternative explanation for increasing multiple myeloma incidence and mortality in the elderly.

Adult↗

PubMed1995

Increasing multiple myeloma mortality rates in the elderly: demonstration of increasing dependency with increasing age upon age group population size.

Multiple myeloma mortality rates in the elderly are increasing. Using published United States mortality data, annual age-specific multiple myeloma mortality rates from 1968 to 1989 were determined for age groups over age 60 and compared to corresponding annual age group population sizes. Rising multiple myeloma mortality rates among the elderly in the United States from 1968 to 1989 were increasingly dependent, with increasing age, upon increasing age group population size. This finding suggests that differential survival, and its effect upon the surviving gene pool in an aging population, may account for observed increasing multiple myeloma mortality rates in recent successive elderly cohorts. A similar conclusion regarding increasing multiple myeloma mortality rates in the elderly has been derived using the Strehler-Mildvan modification of the Gompertz relationship.

Age Distribution↗

PubMed1985

Worldwide distribution of the conjugative Clostridium perfringens tetracycline resistance plasmid, pCW3.

The aim of this study was to test the hypothesis that all conjugative R-plasmids of Clostridium perfringens are closely related to the previously characterized tetracycline resistance plasmid, pCW3. Fourteen conjugative R-plasmids derived from 11 C. perfringens strains isolated in Australia, the United States, France, Belgium, and Japan were analyzed. Eleven of the plasmids encoded tetracycline resistance while three carried both tetracycline and chloramphenicol resistance. Each of these plasmids was compared, by restriction analysis, to the reference plasmid, pCW3. Seven of the tetracycline resistance plasmids had EcoRI, XbaI, and ClaI restriction profiles that were identical to those of the corresponding pCW3 digests. The seven remaining R-plasmids were different from pCW3. Comparison of partial restriction maps of these plasmids with a complete map of pCW3 indicated that they contained at least 17 kb of DNA that also was present in pCW3. Hybridization analysis confirmed that these plasmids shared substantial homology with pCW3. The three tetracycline and chloramphenicol resistance plasmids frequently lost a 6-kb chloramphenicol resistance segment during conjugation. Cloning experiments showed that the chloramphenicol resistance determinant was expressed in Escherichia coli and that the chloramphenicol resistance gene of one of these plasmids, pIP401, was contained within a 1.5-kb region of the 6-kb deletion segment. Hybridization analysis indicated that the deletion segment of pIP401 was related to those of the other two chloramphenicol resistance plasmids. During the course of this study, conjugative R-plasmids which appear to be identical to pCW3 or closely related to pCW3 were identified from C. perfringens strains from human, animal and environmental sources in five countries. It is concluded that C. perfringens strains in humans and animals throughout the world have overlapping gene pools and that all the conjugative C. perfringens R-plasmids examined probably evolved from a pCW3-like element.

Animal Diseases↗

PubMed1983

Sensitivity of Drosophila melanogaster to low concentrations of gaseous mutagens. IV. Mutations in embryonic spermatogonia.

Drosophila embryos were treated with gaseous ethylene dibromide at concentrations ranging from 0.26 to 200 ppm, thereby exposing a homogeneous and non-dividing population of primordial spermatogonia. Mutations were induced at exposures as low as 1 ppm for 3 h indicating the sensitivity of spermatogonia and the usefulness of this life-cycle stage for detection of mutagens. Other advantages of using embryos are also discussed. The relations between exposure vs. percentage of mutations per chromosome tested and vs. percentage of positive males were linear at low exposures indicating the possibility of extrapolation of the data to very low doses and lack of a threshold. For some males 50% of the progeny carried a mutation, and mutations continued to appear in all tested broods providing evidence of damage to stem cells undergoing quasi-dichotomous divisions. Damage to the stem cells is important in terms of total effects on the gene pool and may contribute more mutations than that due to damage in the more sensitive spermatocytes and spermatids. Spermatogonial stages, therefore, should also be considered in mutagen screening and risk-benefit analyses.

Animals↗

PubMed1989

The V-region disease hypothesis: evidence from autoimmune encephalomyelitis.

Experimental allergic encephalomyelitis has been shown to have an immunological basis. In fact, the disease can be induced by T cells specific for myelin basic protein, a molecule found in abundance in the central nervous system. In this article, Ellen Heber-Katz and Hans Acha-Orbea discuss the T-cell receptor (TCR) repertoire of the encephalitogenic T-cell response, and show that a limited V gene pool, in fact a single V beta and two V alpha families, are being used by the PL/J and B10.PL mice and by every rat strain examined, even though the antigenic determinants and the major histocompatibility complex (MHC) molecules are different in all cases. This extraordinary finding suggests that the TCR is involved in encephalitogenicity in a way that not only involves the recognition of antigen in association with MHC, but also as an effector molecule that results in encephalitis. If this is true, it implies that TCRs, in general, play more than one role in mammalian physiology.

Amino Acid Sequence↗

PubMed1994

Analyses and conservation of sequences among the cognate L3 segments of the five United States bluetongue viruses.

We determined the complete nucleotide sequences of the cognate L3 double-stranded RNA (ds-RNA) segments of bluetongue virus (BTV) serotypes 2, 11, and 13 encoding the major viral inner capsid protein, VP3. Each cognate L3 segment was 2772 nucleotides long and contained a single open reading frame (ORF) with an initiation codon at nucleotides #18-20 and a termination codon at nucleotides #2721-2723. This ORF can encode the 901-amino acid VP3 protein (103 kDa) with a calculated isoelectric point of 6. Phylogenetic analyses using both the nucleotide and the deduced amino acid sequences of the L3 cognate gene of the five US BTV serotypes indicated that the BTV-2 serotype recently isolated in Florida was more distantly related than BTV-10, 11, 13 or 17. The five US BTV serotypes were derived apparently from two distinct gene pools, findings consistent with their current geographic distribution in North America.

Amino Acid Sequence↗

PubMed1992

HLA-DR,DQ sequence polymorphisms in Polynesians, Micronesians, and Javanese.

The origins of the Polynesians remain an enigma. Linguistic reconstructions of proto-Austronesian languages suggest a shared origin for Polynesians, Micronesians, and Javanese with dispersal from northern Borneo and Sulawesi. Analysis of 810 chromosomes for nucleotide sequence polymorphism at HLA-DRB1, DRB3, DRB5, DQA1, and DQB1 loci in Polynesian (Rarotonga, Western Samoa, and Niue), Micronesian (Nauru and Kiribati), and Javanese populations showed virtually no overlap of HLA class II haplotypes between contemporary Polynesians and Javanese. Further, there were marked differences in population distributions of some HLA-DRB1 alleles that could not be distinguished in earlier serologic or restriction fragment length polymorphism (RFLP) studies, e.g., for DR12, DRB1*1201 had a frequency of 15%-30% in Polynesians (1% in Micronesians and Javanese), whereas DRB1*1202 had a frequency of 28%-38% in Micronesians and 51% in Javanese (1% in Polynesians). A novel DR6-related allele, DRB1*1408, was found in all three Polynesian study populations. The Polynesian HLA class II genetic repertoire is not readily derived from the island Southeast Asian gene pool.

Adult↗

PubMed1994

Mapping the human genome--friend or foe?

The Human Genome Project represents one of science's most significant advances. It offers to individuals and communities the capacity to make informed and autonomous decisions. However, it also poses fundamental questions which, it is argued, should be in contemplation now. If mechanisms for the resolution of these issues are not in place before the conclusion of the project, and are not available to guide and control its progress, individual privacy may be seriously affected. Employers, insurers and many other groups may seek access to information which would otherwise be confidential to the individual; families may be torn apart by the information held by one member in respect of the collective gene pool of the family unit. The law has a key role to play in encouraging the sensible use of this information, whilst at the same time protecting individuals and their rights.

Confidentiality↗

PubMed1981

Sequence variation in the LEU2 region of the saccharomyces cerevisiae genome.

The LEU2 regions present on yeast plasmid vectors come from two sources, a series of strains derived from S288c and strain M127. The LEU2 region from the S288c series contains a Tyl-17 element with its associated delta sequences and a small repetitive RNA gene while the LEU2 region from M127 which is present on pJDB248, lacks the Tyl-17 element, but carries a delta sequence and a small RNA gene. The various LEU2 plasmids currently in use vary with respect to these sequences depending on which restriction fragment from the region is present on the recombinant molecule. In addition, strain M127 contains three LEU2 homologous sequences that are represented by different EcoRI fragments and which segregate independently at meiosis. Therefore, there are at least four forms of the centromere-distal EcoRI fragment of the LEU2 locus in the Saccharomyces cerevisiae gene pool; these are 7.1 kb, 1.9 kb, 1.48 kb and 1.15 kb long.

3-Isopropylmalate Dehydrogenase↗