Evaluation of bamboo genetic diversity using morphological and SRAP analyses

Bamboo is an important member of the giant grass subfamily Bambusoideae of Poaceae. In this study, 13 bamboo accessions belonging to 5 different genera were subjected to morphological evaluation and sequence-related amplified polymorphism (SRAP) analysis. Unweighted pair-group method of arithmetic averages (UPGMA) cluster analysis was used to construct a dendrogram and to estimate the genetic distances among accessions. On the basis of morphological characteristics, the 13 accessions were distinctly classified into 2 major clusters; 3 varieties, PPYX, PGNK, and PLYY were grouped as cluster A, and 10 accessions were categorized under cluster B. Similarity coefficients ranging from 0.23 to 0.96 indicated abundant genetic variation among bamboo varieties. Approximately 38 SRAP primer combinations generated 186 bands, with 150 bands (80.65%) showing polymorphisms among the 13 accessions. Based on SRAP analysis, 13 bamboo accessions were grouped into 3 major clusters. Five species comprised Cluster I (PASL, PLYY, PTSC, SCNK, and BMAK), which belongs to genus Phyllostachys. Cluster II consisted of 5 varieties, PASL, PLYY, PTSC, SCNK, and BMAK; Cluster III included 3 varieties, PGNK, PLSY, and BMRS. Comparison of the results generated by morphological and SRAP analyses showed that the classification based on SRAP markers was more concordant to the taxonomic results of Gamble than that performed using morphological characters, thus suggesting that SRAP analysis is more efficient in evaluating genetic diversity in bamboos compared to morphological analysis. The SRAP technique serves as an alternative method in assessing genetic diversity within bamboo collections.     

Photosynthetic functions of cembran pines and dwarf pines during winter at timberline as regulated by different temperatures,snowcover and light

Trees at timberline in the high Alps are exposed to a variety of climatic conditions. Most climatic stresses occur during winter and spring, when frost, occasionally low snow cover, and high irradiation interact. In this study, we follow reactions of photosynthesis from high winter to spring in two dominating tree species of the alpine timberline, which may indicate the status of stress response to a changing environment. The results indicate a level of physiological stability in trees, which are important for stabilising natural high mountain ecosystems. Trees of Pinus cembra and of Pinus mugo were selected at altitudes between 1850 m a.s.l. and 1950 m a.s.l. near innsbruck, Austria. At six sampling times from January to May, fast chlorophyll fluorescence was measured in the field and twigs were collected for further investigation in the laboratory. The following measurements were taken: photosynthetic oxygen formation, needle chlorophyll and carotenoid determination, and kinetic studies of the xanthophyll cycle. In general, both tree species showed similar results in most parameters studied. P. mugo seems to have some advantages if winter precipitation is high, when, because of its growth habitus, most needles will be snow covered. Primary photochemistry (trapping per reaction centre) in PS II does not change with sampling dates despite the fact that temperature and light are changing. However, first events in electron transport and whole needle photosynthesis are strongly affected by light and temperature conditions during the days before sampling. The kinetics of the xanthophyll cycle indicate not only light, but also strong temperature effects. P. mugo photosynthesis seems to have a higher stability under changing weather. Both tree species are well prepared to start with photosynthesis in winter, if favourable conditions, like foehn events, occur.     

Inclusive fitness and reproductive strategies in dwarf mongooses

Dwarf mongooses (Helogale parvula) are small, communally breedingcarnivores found in woodland and tree-savanna throughout Africa.Within a pack, socially subordinate mongooses do not normallybreed, yet they invariably participate in all aspects of parentalcare. The primary alternative to tolerating reproductive suppressionis dispersal, which shortens the wait for dominance and breeding.Here, we calculate the annual inclusive fitness payoffs to thedispersing and nondispersing strategies for males and femalesof ages one to seven, using data from a 14-year study in SerengetiNational Park, Tanzania. Factors with effects on inclusive fitnessincluded relatedness to pack mates before and after dispersal,the effect of help on recipients' reproductive success, theprobability of dispersing successfully, the probability of attainingdominance, and reproductive success after attaining dominance.All of these factors differed between male and female dwarfmongooses. We compared the contributions of direct and indirectfitness to the total fitness of mongooses pursuing each of thestrategies, across a range of ages. In our population, dispersaland nondispersal both yielded direct and indirect payoffs atmost ages. For dispersers of both sexes, direct fitness wasthe primary component of total fitness but indirect fitnesswas substantial for young (< 2 years old) dispersers. Fornondispersers of both sexes, indirect fitness was the majorcomponent of total fitness among young mongooses (up to 2 or3 years), but direct fitness was the major component among oldermongooses. By comparing the inclusive fitness payoffs for thetwo strategies, we determined the range of ages at which dispersalshould be favored for each sex. These comparisons correctlypredicted that males should be more dispersive than femalesat all ages, and that males should disperse over a broader rangeof ages.     

Crown conductance in dwarf, medium, and tall pitch pines in the Long Island Pine Plains

The New York Pine Plains are a unique ecosystem with normal statured and a dwarfed variety of pitch pines (Pinus rigida Mill.). Growing interspersed with the dwarf pines are trees of intermediate height and features. Several hypotheses have been put forward as to why some of the trees are dwarfed, but none have been substantiated. In this study, we tested whether dwarf or medium trees are hydraulically limited compared to normally growing trees. Granier style sap flux sensors were installed in three to six trees of each tree type and sap flux was measured in early August 2004. Sap flux measurements were scaled to crown stomatal conductance using leaf area to sapwood area ratios for each tree. Contrary to expectation, dwarf and medium stature trees had very low leaf area to sapwood area ratios, but high crown stomatal conductances compared to normal trees. Analyses of leaf area, ring widths, and crown stomatal conductance indicate that differences between normal, and dwarf and medium pines are not due to hydraulic limitation, but that stunted growth may be due to other causes.     

Abundant mitochondrial genome diversity,population differentiation and convergent evolution in pines.

We examined mitochondrial DNA polymorphisms via the analysis of restriction fragment length polymorphisms in three closely related species of pines from western North America: knobcone (Pinus attenuata Lemm.), Monterey (P. radiata D. Don), and bishop (P. muricata D. Don). A total of 343 trees derived from 13 populations were analyzed using 13 homologous mitochondrial gene probes amplified from three species by polymerase chain reaction. Twenty-eight distinct mitochondrial DNA haplotypes were detected and no common haplotypes were found among the species. All three species showed limited variability within populations, but strong differentiation among populations. Based on haplotype frequencies, genetic diversity within populations (HS) averaged 0.22, and population differentiation (GST and theta) exceeded 0.78. Analysis of molecular variance also revealed that >90% of the variation resided among populations. For the purposes of genetic conservation and breeding programs, species and populations could be readily distinguished by unique haplotypes, often using the combination of only a few probes. Neighbor-joining phenograms, however, strongly disagreed with those based on allozymes, chloroplast DNA, and morphological traits. Thus, despite its diagnostic haplotypes, the genome appears to evolve via the rearrangement of multiple, convergent subgenomic domains.     

Functional and morphological diversity of sperm in Drosophila

Unlike mammals, where the males produce huge quantities of tiny spermatozoa, insects, and Drosophila in particular, exhibit a wide range of reproductive strategies. Sperm gigantism in Drosophila deviates from the rules that normally govern anisogamy, i.e. differences in the size and quantity of male and female gametes. Sperm gigantism has driven anatomical, physiological and cytological adaptations that affect the correlated evolution of the male and female reproductive systems, and has led to the evolution of a new structure, the roller, located between the testis and the seminal vesicle, and to sperm coiling to form pellets. The diversification of sperm strategy is investigated in the light of sexual selection processes that occur in the female genital tract after copulation. These processes, which bias paternity, result from interactions either between spermatozoa from different males, or between the spermatozoa and the environment within the female reproductive tract. In Drosophila, increased sperm size does not confer any reproductive advantage on the male. The evolution of sperm gigantism does not seem to be attributable to competition between spermatozoa from different males, as has been shown to occur in some vertebrate species. Alternative mechanisms, such as interactions between spermatozoa and the female reproductive system, are therefore currently viewed as being more likely explanations. In particular, the impact of sperm size on female reproductive physiology is being investigated to find out whether having large spermatozoa increases the likelihood of male reproductive success. Correlated adaptations of the spermatozoa and female storage organs also seem to be a major factor in determining sperm success, and their role in male-female conflicts is discussed briefly.     

Evaluation of genetic diversity within asparagus germplasm based on morphological traits and ISSR markers

Asparagus officinalis L. is a dioecious perennial plant globally known for its fine flavor and high nutritional value. An evaluation of genetic diversity in 46 asparagus accessions was carried out based on morphological and inter-simple sequence repeat (ISSR) markers. The result show that the coefficient of variation for 20 morphological characteristics is between 12.45 and 62.22%. Factor analysis revealed that nine factors explained 83.37% of the total variance. At Euclidean distance of 135.7, 46 accessions were divided into two clusters. Genetic similarity coefficient (GSC) based on ISSR data ranged from 0.60 to 0.97, suggesting a relatively abundant genetic base. Furthermore, the 46 asparagus accessions could also be grouped into three major clusters at a GSC of 0.74. And there is no significant relation between the two marker systems using the Mantel test. Clustering based on morphological traits compared with that based on ISSR data was not consistent, however, some common groupings were observed between two dendrograms. Therefore the results elucidated asparagus germplasm genetic background and determined hybrid parents, which will facilitate optimal application of asparagus germplasm resources and provide additional data for genetic improvement.

     

Estimation of diversity by morphological markers

A genetic statistical method for estimation of intraspecific diversity of cultivated plants with respect to morphological genes is proposed. The method may be used for estimation of probability distributions of morphological (marker) mutations with respect to the frequencies of their expression and for prediction of experimental parameter such as the total number of markers, the scale (duration) of the experiment that is necessary for detection of a given proportion of the total marker diversity of the species, etc. The method was tested on tomato Lycopersicon esculentum Mill. using data from the SolGenes Internet databank.     

Effects of afforestation with pines on woody plant diversity of Mediterranean heathlands in southern Spain

Open heathlands of the Strait of Gibraltar region constitute a singularvegetation type within the Mediterranean Basin owing to their high biodiversitylevels and distinct features in the biological aspects of endemism. However,they have been traditionally depicted as low profitable, tree-less, barrenlandsand have been either overlooked in conservation policies or included inextensive pine-tree afforestation programmes. Nowadays, most of the existingpine plantations are no longer exploited and have become dense pine woodlands.Here we present the results of a comparative analysis aimed to ascertain theeffects of pine stands on the structure and diversity of the woody component ofthese mediterranean heathlands. Ten sampling sites were located within thestudyarea, each consisting of two adjacent subsamples: an open heathland and aneighbouring heathland under pine-tree cover. Woody species richness andoverallshrub cover was much lower in pine-tree heath understoreys. This drop in coverwas more marked for short-lived species (seeders and withering resprouters),implying a decrease of the life-history diversity and also having noticeableconsequences in homogenizing the floristic composition of heath patches underpine trees. Heathland narrow endemics dropped significantly in pine stands,showing greater sensitivity to afforestation than nonendemics. We suggest thatthe open heathlands of the Strait of Gibraltar should be given furtherattentionin EU and IUCN conservation policies. Programmes should be implemented toprogressively eliminate abandoned pine plantations so as to restore andpreservethese highly diverse mediterranean heathlands.     

Systematic and morphological diversity of endosymbiotic methanogens in anaerobic ciliates

The identities and taxonomic diversity of the endosymbiotic methanogens from the anaerobic protozoaMetopus contortus, Metopus striatus, Metopus palaeformis, Trimyema sp. andPelomyxa palustris were determined by comparative analysis of their 16S ribosomal RNA sequences. Fluorescent oligonucleotide probes were designed to bind to the symbiont rRNA sequences and to provide direct visual evidence of their origins from methanogenic archaea contained within the host cells. Confocal microscopy was used to analyze the morphology of the endosymbionts in whole cells ofMetopus palaeformis, Metopus contortus, Trimyema sp. andCyclidium porcatum. The endosymbionts are taxonomically diverse and are drawn from three different genera;Methanobacterium, Methanocorpusculum andMethanoplanus. In every case the symbionts are closely related to, but different from, free-living methanogens for which sequences are available. It is thus apparent that symbioses have been formed repeatedly and independently. Ciliates which are unrelated to each other (Trimyema sp. andMetopus contortus) may contain symbionts which are closely related, and congeneric ciliates (Metopus palaeformis andM. contortus) may contain symbionts which are distantly related to each other. This suggests that some of the symbiotic associations must be relatively recent. For example, at least one of the symbioses inMetopus must postdate the speciation ofM. palaeformis andM. contortus. Despite this,Metopus contortus, Trimyema sp., Cyclidium porcatum and their respective endosymbionts show sophisticated morphological interactions which probably facilitate the exchange of materials between the partners.     

Aging and reproductive potential in women.

Reproductive potential in women declines with age. Age-related changes in the ovary account for most of this loss of reproductive function. Oocytes, all of which are present at birth, decline in number and quality with age. The endocrine function of the ovary also declines with age, and the ovary becomes unable to sustain its normal function in the neuroendocrine axis. The neuroendocrine axis may be further affected by primary changes occurring in the hypothalamus and pituitary during aging, although this has not been established in humans. Aging also affects the function of the uterus as the endometrium loses its ability to support implantation and growth of an embryo. Diminished uterine function during aging may be due to changes in the uterine vasculature or to changes in the hormone-dependent development of the endometrium. Finally, aging increases a woman's risk of developing medical, gynecologic or obstetric conditions that may impair her fertility. Knowledge of these affects of aging on a woman's reproductive function is essential to advise and treat the growing number of women seeking pregnancy at advanced reproductive age.     

Relationships between the diversity patterns of vascular plants,lichens and invertebrates in the Central Asian forest-steppe ecotone

The Central Asian forest-steppe ecotone has been exposed to large alterations in grazing pressure in the last two decades, but the consequences for biodiversity have not been studied so far. We analyzed the biodiversity of the edges and the interior of Siberian larch forests in the forest-steppes of eastern Kazakhstan (Saur, Kazakh Altai) and western Mongolia (Mongolian Altai, Khangai) across different groups of organisms (vascular plants, epiphytic lichens, soil macroarthropods, oribatid mites, moths). The species richness of these groups was related to each other only at the forest edge, but not in the interior. Species richness of vascular plants, soil macroarthropods and oribatid mites at the forest edges was positively correlated. This indicates that these ground-inhabiting groups of organisms responded similarly to the variation in the grazing pressure of livestock, which is kept at spatially varying densities by mostly nomadic or transhumant herders. The species richness of epiphytic lichens was only positively correlated with that of vascular plants, and the richness of the (volant) moths was not correlated with that of any other group. The complete lack of correlation between the diversity of groups of organisms in the forest interior suggests that the diversity of the five studied groups is controlled by specific environmental factors, including light and moisture. Except for the Mongolian Altai, which was subjected to the highest grazing pressure, vascular plants, lichens, soil macroarthropods, and moths had a higher diversity at the edges than in the interior; the opposite was true for the oribatid mites. The latter probably benefit from the higher soil moisture inside the forest, whereas the other four groups are favored by increased availability of light, the proximity to the steppe with a partial mixing of species pools, and the soil macroarthropods also by increased dung abundance.     

Genetic diversity and differentiation of the extremely dwarf Ficus tikoua in Southwestern China

Fig wasps are short-lived, weak fliers, and their long-distance dispersal depends on the ability to enter fast-flowing air above the canopy. Therefore, growth form of fig species may affect fig wasps’ dispersal. We employed six microsatellite markers to examine gene flow in Chinese populations of the dioecious Ficus tikoua, a prostrate shrub with figs partially buried in the soil. Moderate genetic diversity was found within populations of F. tikoua. Differentiation among six F. tikoua populations (F_ST = 0.196, p < 0.001) was higher than those of other dioecious figs, and significant differentiation was found between each pair of populations, indicating potential restricted gene flow. This was further demonstrated by significant isolation-by-distance pattern (p = 0.039), because low gene flow among population was needed to balance the minor effect of genetic drift, given F. tikoua was locally common. Restricted gene flow suggests that growth form may determine differences in gene flow between fig species.     

Synthetic cannabinoids and potential reproductive consequences

Increases in emergency room visits due to abuse of designer drugs, popularly known by the street names “K2” and “Spice,” are a cause for social, judicial, and clinical concerns. The psychoactive components in these herbal drugs mainly consist of different synthetic cannabinoids, and users of these street drugs are primarily within the age group of 12 to 20 years old. The abusive use of synthetic cannabinoids results in anxiety, nausea, vomiting, tachycardia, elevated blood pressure, tremors, seizures, hallucinations, and paranoid behavior, but the effects of maternal use of synthetic cannabinoids during pregnancy are ambiguous due to limited studies in humans and a relative short history of the drugs. In this review, we discuss the known and potential adverse effects of synthetic cannabinoids on human pregnancy using knowledge gathered from studies in mice and limited studies in humans. In mice, multiple sites and stages of pregnancy are potential targets of synthetic cannabinoids, including preimplantation embryo development, oviductal embryo transport, implantation, placentation, and parturition. It is anticipated that maternal use of synthetic cannabinoids would result in severely compromised female fertility and pregnancy outcome.     

Temporal flux in the morphological and molecular diversity of UK barley

Genetic-diversity assessments, using both phenotypic and molecular-marker data, were made on a collection of 134 barley varieties (both winter and spring types), chosen on the basis of their representation on the NIAB "Recommended List" over the period 1925-1995. Genotypic (AFLP and SSR) and phenotypic (UPOV characters) data were analysed to determine short- and long-term temporal trends in diversity over the period. A consistent pattern emerged demonstrating that only a minor proportion of the overall variance appears to be the result of any temporal drift, although there were strong indications of qualitative shifts in diversity, probably related to the changing relative acreage of winter and spring barleys over the study period. Our overall conclusions are that systematic plant breeding does not inevitably lead to a reduction in the genetic diversity of agricultural crops, and that diverse breeding programmes and the variety delivery systems in place in the UK have generally been successful in maintaining sufficient genetic diversity to allow the steady rise in genetic potential that has been a feature of 20th century crop breeding. The concentration of breeding effort into a smaller number of independent programmes is likely to be prejudicial to the maintenance of the genetic diversity of a crop.     

Axonal terminals of sensory neurons and their morphological diversity

The application of electron microscopy to defining the fine structural characteristics of axon terminals and synapses was followed by a half century of intensive exploration of the molecular concomitants of synaptic activity. The summer of 2003 marks the 50th anniversary of the earliest accounts of synapses by Palay and Palade. Prompted by recent findings of specialization in the fine structure of nociceptor terminals that lack contacts remotely resembling a synapse, we present a survey of arrangements, contacts and axoplasmic contents of peripheral sensory axon terminals. The morphological principles underlying the variety of small, clear, spherical vesicles, mitochondrial aggregation, the membrane thickenings associated with sensory terminals and the organelles or inclusions associated with the site of transduction apparently do not conform to a simple parsimonious rule. It is also evident that the terminal of the central branch of bifurcated sensory axons differs structurally from its distal counterparts. This brief illustrated account addresses some important unresolved problems in the functional interpretation of the diverse morphological features exhibited in both synaptic and non-synaptic sensory axon terminals with the aim of identifying and emphasizing some key questions amenable to resolution with contemporary morphological and physiological techniques.     

Neighborhood density and reproductive potential in harvester ants

When neighbors compete for resources, the characteristics of a neighborhood may affect fitness. We examined the relationship between reproductive success and the density and size/age characteristics of neighbors in a population of the seed-eating ant, Pogonomyrmex barbatus, in which the ages of all colonies were known. Reproductive success was estimated by trapping and counting the number of alate, reproductive ants emerging from the nest for the annual mating flight. Alate production was negatively related to neighborhood density. Decreased production of alates by more crowded colonies may be due to competition for food with surrounding colonies. Neighbor size/age was unrelated to alate production. If alate production is correlated with lifetime reproductive success, these results suggest that selection favors colonies that monopolize more space, whatever the size of neighboring colonies. Received: 12 February 1996 / Accepted: 6 September 1996