Correlations between characteristics of evoked EEG potentials recorded in a go/no-go paradigm and indices of attention in children

We studied correlations of the parameters of evoked EEG potentials (EPs) with the indices of attention in 30 children (12 years old). The EP were recorded in a two-stimulus go/no-go paradigm; the time of reaction was also measured. The indices of attention were measured using a Burdone test (correction trial) and Schulte’s tables. Optimum characteristics of attention were found in children with high amplitudes of the P2 component, P300 wave, and contingent negative deviation, low amplitudes of the N2 component, and small values of the latencies of the P1-N1-P2 complex. Neirofiziologiya/Neurophysiology, Vol. 37, Nos. 5/6, pp. 452–458, September–December, 2005.     

Alzheimer’s disease and normal aging: Neurophysiological and immunological aspects

We studied in humans the characteristics of brain visual evoked potentials (EP) elicited by presentation of a reverse chess-board patterns and also the following parameters of the immune status: the numbers of T- and B-lymphocytes, immunoglobulin levels in blood plasma, and level of sensibilization of lymphocytes to the brain antigen. Two groups were examined: aged persons (up to 65 years) with normal course of aging (the control group) and patients of the same age suffering from Alzheimer’s disease (AD). In the latter group, lower amplitudes of early and late EP components (P300, in particular) and longer peak latencies of late components were observed. The development of AD correlates with a drop in the number of lymphocytes, increased IgA level, and sensibilization of lymphocytes to brain antigen, which is indicative of an immunodeficit state and the development of an autoimmune process; the latter phenomena can be significant factors responsible for neuronal death.     

Hemodynamic indices of the cardiovascular system in children as related to their constitutional characteristics

In children five to seven years of age, the adaptation of their cardiovascular system to a high physical activity as related to their individual somatic characteristics was studied. The methods of rheography and bicycle ergometry were used under physical loads with the power increasing from 1 and 1.5 W/kg body weight. During exercises, load grading according to the body’s somatic characteristics led to a significant increase in the degree of the children’s functional training. In children of different somatotypes, the indices of absolute physical efficiency and of both cardiac output (Q) and stroke volume (SV) increased significantly. The increase in hemodynamic indices in girls was higher than in boys of the same age.     

A genetic bottleneck in the ’evolution under domestication’ of upland cotton Gossypium hirsutum L. examined using DNA fingerprinting

Reliable information about the evolutionary and genetic relationships of various germplasm resources is essential to the establishment of rational strategies for crop improvement. We used AFLPs to study the genetic relationships of 43 cultivars of Gossypium hirsutum representative of the genomic composition of modern ’Upland’ cotton. The study also included representatives of the related tetraploid species Gossypium barbadense, as well as the diploid species Gossypium raimondii, Gossypium incanum, Gossypium herbaceum and Gossypium arboreum. We tested 20 primer combinations that resulted in a total of 3,178 fragments. At the species level, and above, genetic similarities based on AFLPs were in agreement with the known taxonomic relationships. Similarity indices ranged from 0.25 to 0.99. Representatives of the G. hirsutum germplasm resources utilized in North America, including secondary accessions collected by breeders in Central America (’Acala’, ’Tuxtla’, ’Kekchi’) and the southwestern US (’Hopi Moencopi’), formed a single cluster with exceedingly limited genetic diversity (with many pairwise similarity indices >0.96) We concluded that these accessions were derived from the same genetic pool. The early maturing or ’latifolium’ or ’Mexican Highlands’ cultigens from which these cultivars were derived appear to have had extremely limited genetic diversity, perhaps as a result of a severe genetic bottleneck resulting from the selection pressures of domestication. Outside of the major G. hirsutum cluster, well-supported phylogenies were inferred. Inside this cluster, phylogenies were obscured by limited diversity, reticulation and lineage sorting. The implications of these findings for cotton improvement are discussed. Received: 23 May 2000 / Accepted: 23 January 2001     

Who Cares About Marrying a Rich Man? Intelligence and Variation in Women’s Mate Preferences

Although robust sex differences are abundant in men and women’s mating psychology, there is a considerable degree of overlap between the two as well. In an effort to understand where and when this overlap exists, the current study provides an exploration of within-sex variation in women’s mate preferences. We hypothesized that women’s intelligence, given an environment where women can use that intelligence to attain educational and career opportunities, would be: (1) positively related to their willingness to engage in short-term sexual relationships, (2) negatively related to their desire for qualities in a partner that indicated wealth and status, and (3) negatively related to their endorsement of traditional gender roles in romantic relationships. These predictions were supported. Results suggest that intelligence may be one important individual difference influencing women’s mate preferences.     

Correlations between indices of P300 EEG potential,cognitive tests,and variational pulsometry in Parkinsonian patients

The parameters of an event-related EEG potential (ERP), P300 wave, are now extensively used as objective neurophysiological indices of the state of cognitive functions. At the same time, information on the effects of the autonomic nervous system on the parameters of P300 is limited. In Parkinson’s disease clinics, in addition to the leading motor disorders, more or less clear psychoemotional, cognitive, and autonomic (in particular cardiovascular) impairments are usually observed. This allows one to study the dependence between the cardiovascular dysfunction and intensity of cognitive disorders in Parkinsonian patients. In our study on this contingent, we analyzed correlations between the parameters of P300 potential, indices of the state of the cognitive sphere (determined using a questionnaire, Mini Mental State Examination, MMSE, and a Luriya’s test), and indices of variational pulsometry. Thirty-five Parkinsonian patients (49 to 74 years, severity of disease 1.5 to 3.0 by the international classification) were examined. We found a negative influence of excessive sympathetic tonus in cardiovascular control on the state of cognitive functions. The latency of P300 potential was longer in patients with greater intensities of sympathetic influences on the cardiovascular system. The coefficients of correlation of the latency of P300 with the amplitude of mode of R-R intervals (AMo), index of tension in the regulatory systems by Baevskii (IT), and index of autonomic balance by Baevskii (IAB) were 0.52 (P < 0.01), 0.36 (P < 0.05), and 0.37 (P < 0.05), respectively. The above autonomic indices demonstrated significant negative correlations with the volume of short-term memory measured by Luriya’s test. The P300 latency, in turn, showed negative correlations with the memory volume estimated by the MMSE scale and Luriya’s test. With increase in the age of patients, the degree of the above-mentioned correlations between the P300 latency, memory volume (by Luriya’s test), and parameters of variational pulsometry increased. Our data emphasize the expedience of “routine” studies of the balance of sympathetic and parasympathetic control in pathological states accompanied by clear or subclinical cognitive disorders. Early recognition of cardiovascular dysfunction and its corresponding therapeutic correction should improve the state of brain functions and quality of life in patients suffering from neurodegenerative diseases, in particular from Parkinson’s disease. Neirofiziologiya/Neurophysiology, Vol. 40, No. 1, pp. 43–52, January–February, 2008.     

Optimization of combined genetic gain and diversity for collection and deployment of seed orchard crops

Genetic gain and diversity of seed orchards’ crops are determined by the number of parents, their breeding values and relatedness, within-orchard pollination efficiency, and level of pollen contamination. These parameters can be manipulated at establishment by varying clonal representation (e.g., linear deployment), during orchard development by genetic thinning, or by selective harvesting. Since clonal fecundities are known to vary both within and among years, then each seed crop has a unique genetic composition and, therefore, crops should be treated on a yearly basis. Here we present an optimization protocol that maximizes crop’s genetic gain at any desired genetic diversity through the selection of a subset of the crop that meets both parameters. The genetic gain is maximized within the biological limit set by each clone’s seed-cone production and effective population size is used as a proxy to genetic diversity whereby any relationship among clones is considered. The optimization was illustrated using 3 years’ reproductive output data from a first-generation western larch seed orchard and was tested under various scenarios including actual male and female reproductive output and male reproductive output assumed to be either equal to that of female or a function of clonal representation. Furthermore, various levels of co-ancestry were assigned to the orchard’s clones in supplementary simulations. Following the optimization, all solutions were effective in creating custom seedlots with different gain and diversity levels and provided the means to estimate the genetic properties of composite seedlots encompassing the remaining “unused” seed from a number of years.     

Material basis for inhibition of Dragon’s Blood on evoked discharges of wide dynamic range neurons in spinal dorsal horn of rats

In vivo experiments were designed to verify the analgesic effect of Dragon’s Blood and the material basis for this effect. Extracellular microelectrode recordings were used to observe the effects of Dragon’s Blood and various combinations of the three components (cochinchinenin A, cochinchinenin B, and loureirin B) extracted from Dragon’s Blood on the discharge activities of wide dynamic range (WDR) neurons in spinal dorsal horn (SDH) of intact male Wistar rats evoked by electric stimulation at sciatic nerve. When the Hill's coefficients describing the dose-response relations of drugs were dif-ferent, based on the concept of dose equivalence, the equations of additivity surfaces which can be applied to assess the interaction between three drugs were derived. Adopting the equations and Tal-larida's isobole equations used to assess the interaction between two drugs with dissimilar dose-response relations, the effects produced by various combinations of the three components in modulating the evoked discharge activities of WDR neurons were evaluated. Results showed that Dragon’s Blood and its three components could inhibit the evoked discharge frequencies of WDR neurons in a concentration-dependent way. The Hill's coefficients describing dose-response relations of three components were different. Only the combined effect of cochinchinenin A, cochinchinenin B and loureirin B was similar to that of Dragons Blood. Furthermore, the combined effect was synergistic. This investigation demonstrated that through the synergistic interaction of the three components Dragon’s Blood could interfere with the transmission and processing of pain signals in spinal dorsal horn. All these further proved that the combination of cochinchinenin A, cochinchinenin B, and loureirin B was the material basis for the analgesic effect of Dragon’s Blood.     

Age-related changes in saccadic eye movements in healthy subjects and patients with Parkinson’s disease

The age-related changes in saccadic eye movements (the latency, the duration of single saccades and the percentage of multistep saccades) were compared in healthy subjects and patients with Parkinson’s disease. Healthy volunteers without neurological symptoms were divided into six age groups: (17–20, 21–30, 31–40, 41–50, 51–60, and 61–75 years of age); and parkinsonian patients, into three groups (41–50, 51–60, and 61–75 years of age). According to the data obtained, the saccade characteristics depend on the age in both the subjects without neurological symptoms and parkinsonian patients. In healthy volunteers, the percentage of multistep saccades and the mean saccade latency increase significantly after the age of 60 years. These parameters in patients with Parkinson’s disease significantly exceed the values in healthy subjects from the age-matched groups. The “disease” factor has a greater influence on the saccade latency and the percentage of multistep saccades than the “age” factor. The duration of single saccades depends on age to a lesser degree and does not change in patients with Parkinson’s disease. The peculiarities of the development of neurodegenerative processes in cases of normal aging and in idiopathic parkinsonism are discussed.     

The sociological critique of evolutionary psychology: Beyond mass modularity

This paper addresses evolutionary psychology's (EP's) mass modularity account of human intelligence. First, EP is located within 'naturalization of society' discourses. Secondly, the nature and weakness of mass modularity theory is examined. In the third part of the paper, the genetic reductionism of EP is challenged with reference to developmental systems theory (DST). However, in the fourth part, the danger of importing one biological theory to defuse the colonial ambitions of another is highlighted through an examination of sociological systems theory and its relationship with biological systems theory. Nevertheless, DST has stimulated valuable insights in theoretical sociology/anthropology. Modularity is also common in computer models of intelligence as algorithmic computation. EP draws parallels with computer modelling to claim confirmation of its own account. The fifth part of this article challenges the validity of this parallel, drawing upon Harry Collins's sociology of what humans and computers can do. Collins's work highlights the non-modular cultural 'rules' that today's computers cannot follow. In the light of these theoretical and empirical developments I conclude that contemporary sociology offers a valuable and systematic counter to discourses of genetic reductionism and the discourses of technological determination upon which they are parasitic.     

Relationship between genetic anomalies of different levels and deviation in dermatoglyphic traits

The present study is carried out to evaluate the effect of chromosomal morbidity (82% are 47XXY and in the remaining cases there is the extra X and/or Y) in the males with Klinefelter’s syndrome, based on dermatoglyphic traits and indices of diversity and asymmetry. The main objectives of the present study is to find dermatoglyphic traits and fluctuating asymmetry indices which could be “marker traits” and could indicate the degree of developmental instability of the organism. The sample of males with Klinefelter’s syndrome (N=171) was collected in the Institute of Human Genetics of Sheba Medical Center, Ramat-Gan, Israel, by Professor Bat-Miriam Katznelson during 20 years, between 1968–1988. All patients were confirmed by chromosomal examination. The finger and palm prints were collected with the aid of pads manufactured by Lamedco Inc., Knoxville, Tennessee, U.S.A. Interpretation of the prints was according to Cummins and Midlo (1961) and Penrose (1968) and included identification of patterns, ridge counts and the measurements of distances sum of and angles in the palms. 79 dermatoglyphic variables for every patient: 28 continuous traits, 9 discrete traits, 11 indices of intra-individual diversity, 15 indices of directional asymmetry and 16 indices of fluctuating asymmetry were estimated. The problem of asymmetry, fluctuating and directional and of intraindividual diversity of quantitative dermatoglyphic traits is reviewed here as well as illustrated by data obtained on a sample of healthy control group of Jews from Israel. In this first part of our paper we will discuss the data on individual dermatoglyphic traits on digits and palms. The second part will be dedicated to multivariate analysis in order to compare between Klinefelter’s syndrome and control healthy individuals based on quantitative dermatoglyphic traits and indices of diversity and asymmetry.     

Callus induction and micropropagation improved by colchicine and phytoregulators in Kappaphycus alvarezii (Rhodophyta, Solieriaceae)

Tissue culture techniques were applied for micropropagation of the red alga Kappaphycus alvarezii in order to select the best strain and experimental system for in vitro culture. Five strains were tested: brown (BR), green (GR) and red (RD) tetrasporophytes, brown female gametophyte (BFG), and a strain originating from tetraspore germination (“Edison de Paula”, EP). The effects of three culture media were tested on callus formation, regeneration from explants and from callus in the three tetrasporophytic and EP strains: seawater enriched with half-strength of von Stosch’s (VS 50) and Guillard & Ryther’s (F/2 50) solutions, plus synthetic ASP 12-NTA medium, with or without gelling agent. Explants of the EP strain were treated with glycerol and the phytoregulators indole-3-acetic acid (IAA); 2,4-diclorophenoxyacetic acid (2,4-D); and benzylaminopurine (BA), alone or in combination. The effects of colchicine (0.01%) during 24, 48, 72 hours and 14 days were analyzed in the BFG and EP strains. The EP strain showed the highest percentage of explants forming callus and regeneration from explants in VS 50, indicating its high potential for micropropagation in comparison to the other strains. Regeneration from callus was very rare. Treatments with glycerol and IAA:BA (5:1 mg L⁻¹) stimulated the regeneration from explants. Significant differences were observed in the percentages of regeneration of EP strain explants treated with colchicine for 14 days. Our results indicate that IAA and BA stimulated the regeneration process, and that colchicine produced explants with high potential for regeneration, being useful for improving the micropropagation of K. alvarezii.     

Are fish early growth and condition patterns related to life-history strategies?

Life-history studies provide a global framework for comparison of fish species responses and trade-offs facing ecological and environmental constrains. A broad comparison among fishes’ early growth and condition traits is performed in order to determine ecological patterns of early development regarding latitudinal distribution, habitat use and life-history strategies. Based on Winemiller and Rose (1992) classification of life-history strategies, data on early growth and condition indices of 46 fish species worldwide was analysed. Available information on fishes’ early features, namely first year length percentage (relative to species maximum theoretical length), age at maturation and Fulton’s condition index (K), provided a good segregation of species by latitudinal distribution and habitat use, and evidenced the categories of the three-endpoint model. Higher larvae and juvenile growth rates and condition indices (K, mean RNA–DNA ratios and protein contents) were associated with tropical and temperate fish species that occur in complex or variable habitats (respectively coral reefs and estuaries). These species selected for the opportunistic and periodic strategies, investing highly in rapid growth in order to increase survival probability to counter high mortality rates during early stages or unstable habitat conditions. Later age at maturation, slower larvae and juvenile growth as well as lower mean condition indices were consistent with fish species from more stable or predictable environments, as polar regions and freshwater habitats, which selected for the equilibrium strategy. Nonetheless, differences in energy allocation strategies during early stages were not observed, evidencing the scarcity of available data regarding condition indices and/or the importance of integrating life-history intermediate strategies. Future research into condition indices and other physiological processes, for a broader set of species and for a wider latitudinal and habitat range including seasonal variability (particularly for species from tropical and polar regions), is essential to better understand or test current theories of species ecological patterns. The use of direct quantitative measures of young fishes’ metabolic investment and fitness constitutes a new approach for life-history studies, and should be fundamental for predicting species’ responses to acute environmental or human constrains, especially in a global climate change scenario that is expected to affect distribution and abundance of fish species worldwide.     

Age-dependent cognitive defects caused by local brain lesions of various geneses

The results of neuropsychological analysis of 808 children and adolescents 7–18 years of age were studied. Among the test subjects, 689 children were patients with local brain lesions (tumors, arachnoid cysts, vascular pathology, and congenital hydrocephaly) and 119 children were healthy. Both patients and healthy subjects were divided into four age groups: junior school age (7–9 years), prepubertal age (10–12 years), pubertal age (13–15 years), and senior school age (16–18 years). Cognitive defects were found and demonstrated to depend on the test subject’s age and the type of brain pathology.     

Identification of a major QTL for time of initial vegetative budbreak in apple (<Emphasis Type="Italic">Malus</Emphasis> x <Emphasis Type="Italic">domestica</Emphasis> Borkh.)

In the Western Cape region of South Africa, dormancy release and the onset of growth does not occur normally in apple (Malus x domestica Borkh.) trees during spring due to the mild winter conditions experienced and fluctuations in temperatures experienced during and between winters. In this region, the application of chemicals to induce the release of dormancy forms part of standard orchard management. Increasing awareness of the environmental impact of chemical sprays and global warming has led to the demand for new apple cultivars better adapted to local climatic conditions. We report the construction of framework genetic maps in two F1 crosses using the low chilling cultivar ‘Anna’ as common male parent and the higher chill requiring cultivars ‘Golden Delicious’ and ‘Sharpe’s Early’ as female parents. The maps were constructed using 320 simple sequence repeats, including 116 new markers developed from expressed sequence tags. These maps were used to identify quantitative trait loci (QTL) for time of initial vegetative budbreak (IVB), a dormancy related characteristic. Time of IVB was assessed four times over a 6-year period in ‘Golden Delicious’ x ‘Anna’ seedlings kept in seedling bags under shade in the nursery. The trait was assessed for 3 years on adult full-sib trees derived from a cross between ‘Sharpe’s Early’ and ‘Anna’ as well as for 3 years on replicates of these seedlings obtained by clonal propagation onto rootstocks. A single major QTL for time of IVB was identified on linkage group (LG) 9. This QTL remained consistent in different genetic backgrounds and at different developmental stages. The QTL may co-localize with a QTL for leaf break identified on LG 3 by Conner et al. (1998), a LG that was, after the implementation of transferable microsatellite markers, shown to be homologous to the LG now known to be LG 9 (Kenis and Keulemans 2004). These results contribute towards a better understanding regarding the genetic control of IVB in apple and will also be used to elucidate the genetic basis of other dormancy related traits such as time of initial reproductive budbreak and number of vegetative and reproductive budbreak.     

Genetic variability of Chalara fraxinea, dieback cause of European ash (Fraxinus excelsior L.)

A total of 159 colonies of Chalara fraxinea were isolated between 2005 and 2006 from dying trees of European ash (Fraxinus excelsior L.) aged between 3 and 10 years. They derived from five regions of Poland differing by geographic location and climatic conditions. On the basis of 90 RAMS markers, pathogen intra- and inter-population variability, as well as its dependency on geographic distance and climatic conditions in the regions of strain origin, was analysed. The applied measures of intrapopulation genetic variability (genetic distance, Nei’s unbiased diversity, Shannon’s Information Index and percentage of polymorphic loci) allowed for differentiation of two strain groups: the first deriving from lowlands and the second from uplands and mountainous areas. Strains in lowlands were characterised by smaller number of markers, smaller number of polymorphic loci and smaller intrapopulation genetic variability. Positive and statistically significant correlation was shown between variability of isolates and elevation of regions above sea level. Pair-wise genetic distances between groups of isolates (Nei’s unbiased genetic distance) from particular regions were not significantly correlated with the corresponding geographic distances. On the basis of AMOVA, it was shown that 85% of variability was within-region differences and 2% between-region differences, whereas differences between lowlands and uplands were 13%. Principal Components Analysis (PCA) for the investigated regions confirmed the results from Nei’s genetic distance matrix.     

The biodiversity of air spora in an Italian vineyard

Biodiversity indices are frequently used to provide a numerical value of the diversity of species within an ecological community. To study fungal biodiversity in the air, a 7-day recording Hirst-type spore trap was used. The daily concentration of 124 taxa was recorded in an Italian vineyard. The predominant fungi were: Cladosporium spp., unknown 3-septate fusiform spore, and Alternaria spp. Shannon’s and Simpson’s biodiversity indices and evenness were calculated first for air spora. Meteorological circumstances affected the biodiversity; positive correlations were found between Simpson’s biodiversity index and precipitation, but no significant correlations were found with Shannon’s diversity index and evenness. To predict Simpson’s index for airborne fungi, regression analysis was performed. It was shown that the best estimator, sun hours, negatively affected the index. The biodiversity of the dominant species was low on dry days, since Cladosporium alone had much higher abundance on such days than other species.     

Correlation of the characteristics of EEG potentials with the indices of attention in 12-to 13-year-old children

We studied correlations of the spectral characteristics of EEG with the indices characterizing the level of attention in 60 children (12 to 13 years old). Indices of voluntary attention were measured using a complex of psychological tests, including a Bourdon’s test (correcture test), a two-stimulus go/no-go test, a computer test (a modification of the Bourdon’s test for characterization of concentration and stability of attention), and Schulte’s tables. Children manifesting a good working ability (corresponding to the results of the go/no-go test and correcture test) showed relatively high values of the ratio of spectral powers (SPs) of the beta 1 and theta rhythms. These ratios were greater in the right hemisphere; this is probably indicative of a greater contribution of neuronal mechanisms of this hemisphere to providing watchfulness and stability of attention. Children demonstrating increased impulsivity (according to the results of the go/no-go test) were characterized by low modal frequencies of the alpha rhythm in the occipital brain regions, while children with relatively high values of this frequency in various cerebral regions demonstrated high indices of attentiveness and rates of the cognitive processes. Children performing the test task with especially high accuracy were characterized by high ratios of SPs of the low-frequency beta rhythm vs theta rhythm (mostly in the central and parietal regions of both hemispheres). The approach we have applied can be used for measuring the objective indices characterizing the state of the attention sphere in children. Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 248–256, May–June, 2006.     

Cancer,Viruses, and Mass Migration: Paul Berg’s Venture into Eukaryotic Biology and the Advent of Recombinant DNA Research and Technology, 1967–1980

The existing literature on the development of recombinant DNA technology and genetic engineering tends to focus on Stanley Cohen and Herbert Boyer’s recombinant DNA cloning technology and its commercialization starting in the mid-1970s. Historians of science, however, have pointedly noted that experimental procedures for making recombinant DNA molecules were initially developed by Stanford biochemist Paul Berg and his colleagues, Peter Lobban and A. Dale Kaiser in the early 1970s. This paper, recognizing the uneasy disjuncture between scientific authorship and legal invention in the history of recombinant DNA technology, investigates the development of recombinant DNA technology in its full scientific context. I do so by focusing on Stanford biochemist Berg’s research on the genetic regulation of higher organisms. As I hope to demonstrate, Berg’s new venture reflected a mass migration of biomedical researchers as they shifted from studying prokaryotic organisms like bacteria to studying eukaryotic organisms like mammalian and human cells. It was out of this boundary crossing from prokaryotic to eukaryotic systems through virus model systems that recombinant DNA technology and other significant new research techniques and agendas emerged. Indeed, in their attempt to reconstitute ‹life’ as a research technology, Stanford biochemists’ recombinant DNA research recast genes as a sequence that could be rewritten thorough biochemical operations. The last part of this paper shifts focus from recombinant DNA technology’s academic origins to its transformation into a genetic engineering technology by examining the wide range of experimental hybridizations which occurred as techniques and knowledge circulated between Stanford biochemists and the Bay Area’s experimentalists. Situating their interchange in a dense research network based at Stanford’s biochemistry department, this paper helps to revise the canonized history of genetic engineering’s origins that emerged during the patenting of Cohen–Boyer’s recombinant DNA cloning procedures.     

Genetic population structure of a reef goby, <Emphasis Type="Italic">Bathygobius cocosensis</Emphasis>, in the northwestern Pacific

To investigate the genetic population structure of a reef goby, Bathygobius cocosensis, in the northwestern Pacific in relation to major oceanic currents (North Equatorial and Kuroshio Currents), the mitochondrial DNA (mtDNA) phylogeny and demography of the species were inferred from partial nucleotide sequences of the mitochondrial NADH dehydrogenase 5 subunit (ND5) gene (945 bp). The resultant mtDNA tree and population genetic analyses showed that the Bonin Islands’ population apparently differed from the other populations in the Japan–Ryukyu–Guam region, which lie along the routes of the North Equatorial and Kuroshio Currents. A test calculation indicated the divergence date to be approximately 1 million years ago. The population expansion parameters indicated that the Bonin Islands’ population had survived during the fluctuations in sea level in the Pleistocene–Holocene age and that the population had expanded thereafter.