Cytogenetic Follow-Up in a Case With a Primary Cutaneous Melanoma and Five Metastatic Lesions

Cytogenetic analyses conducted on several cases of melanoma have contributed to the identification of the chromosomal regions where the sequences responsible for malignant transformation and the evolution of this tumor are probably located. With regard to these problems, it is very important to have the possibility to analyze, through the use of cytogenetics, both the primary melanoma and the metastatic lesions from the same patient. We present a case in which the primary melanoma and five different metastases were studied by using cytogenetics. The primary tumor showed an inversion of chromosome 1 where the p36 region, often proposed in literature as the location of a melanoma susceptibility gene, was involved. Three cutaneous and one lymphonodal metastases presented the same nine clonal chromosomal aberrations. In particular, one is a further rearrangement of the marker present in the primary tumor; another is a deletion of the 9p21pter region in which the p16 gene is located. Our results can provide a contribution to the hypothesis of the location of a candidate gene for melanoma in the 1p36 region and can also underscore the role of the 9p21 region in the progression of melanoma.     

Above-ground competition does not alter biomass allocated to roots in Abutilon theophrasti

We tested whether plants allocate proportionately less biomass to roots in response to above-ground competition as predicted by optimal partitioning theory. Two population densities of Abutilon theophrasti were achieved by planting one individual per pot and varying spacing among pots so that plants in the two densities experienced the same soil volume but different degrees of canopy overlap. Density did not affect root:shoot ratio, the partitioning of biomass between fine roots and storage roots, fine root length, or root specific length. Plants growing in high density exhibited typical above-ground responses to neighbours, having higher ratios of stem to leaf biomass and greater leaf specific area than those growing in low density. Total root biomass and shoot biomass were highly correlated. However, storage root biomass was more strongly correlated with shoot biomass than was fine-root biomass. Fine-root length was correlated with above-ground biomass only for the small subcanopy plants in crowded populations. Because leaf surface area increased with biomass, the ratio between absorptive root surface area and transpirational leaf surface area declined with plant size, a relationship that could make larger plants more susceptible to drought. We conclude that A. theophrasti does not reallocate biomass from roots to shoots in response to above-ground competition even though much root biomass is apparently involved in storage and not in resource acquisition.     

The seasonal dynamics and distribution of Chaoborus flavicans larvae in adjacent lake basins of different morphometry and degree of eutrophication

1.  Seasonal dynamics, spatial distribution and population size of the phantom midge Chaoborus flavicans in different parts of the eutrophic Lake Hiidenvesi (30.3 km²) were studied.
2.  Density of larvae was low in the shallow, most eutrophic parts of the lake, while the deep Kiihkelyksenselkä basin was inhabited by a dense population. In the deepest part of Kiihkelyksenselkä (33 m) density was 13 989 ± 3542 m^–2 in May, declined to 1102 ± 274 m^–2 in July and recovered to 7225 ± 1314 m^–2 by October. In spring and autumn the majority of larvae were benthic while, during high summer, few larvae were found in the sediment.
3.  Horizontal distribution fluctuated seasonally. On 3 June < 5% of the population inhabited areas shallower than 10 m. On 6 July the limnetic fraction was still restricted to regions deeper than 10 m, but 43% of benthic larvae were found between 6 and 10 m depths. In October both limnetic and benthic larvae were concentrated in areas deeper than 20 m.
4.  Within the lake, distribution was mainly regulated by stratification characteristics, degree of eutrophy being less important. The seasonal horizontal movements were probably induced by food shortage. Larvae could not meet their energetic demands in stratified areas and dispersed to shallower water, reducing predation risk by use of the benthic habitat.     

Spatial and temporal response of stream bacteria to sources of dissolved organic carbon in a blackwater stream system

1. We hypothesized that changes in bacterial colony growth would be correlated to shifts in riparian vegetation (via leachate quality) along a river continuum of a south-eastern, blackwater stream (U.S.A.). Spatially, we expected bacterial assemblages from downstream reaches to utilize more sources of leachate and at higher concentrations than bacteria collected from headwater reaches. Temporally, we predicted higher colony growth on leachate from autumn-shed (senescent) leaves compared with leachate from fresh, green leaves.
2. We examined spatial differences in assemblage growth by culturing bacteria sampled along the stream continuum on gradient plates using leachates from four common riparian species ( Taxodium distichum , Carya spp., Acer rubrum and Decumaria barbara ). Bacteria from the lowest site were able to use all sources provided and at all concentrations, whereas bacteria from upper reaches could not. Colony density was correlated to relative leachate concentration at all sites along the continuum.
3. Leachates from fresh and senescent A. rubrum leaves were used to determine temporal differences. Winter assemblages of bacteria could not grow on fresh leaf leachate at any concentration but grew well on autumn leaf leachate at higher concentrations. Differential response of bacterial assemblages indicated local adaptation to potential sources of dissolved organic matter.
4. Growth response of stream bacterial colonies appeared to be dependent on the timing and source of leachate as well as on sources of dissolved organic carbon from further upstream. Growth of bacterial assemblages exhibited 'generalist' characteristics in headwater reaches and 'specialist' characteristics at the mouth of our study stream drainage. Thus, our findings lend support to the argument that variable resource habitats favour a small, generalist assemblage, while environments with stable resource supplies allow for highly diverse assemblages dominated by specialists.     

Population differentiation in the marginal populations of the great tit (Paridae: Parus major)

The major subspecies group of the great tit, Parus major , has experienced demographic and spatial expansions during the last century in several sites at the edges of its distribution range. These expansions, although temporarily very even, have resulted in dissimilar patterns of molecular diversity. Populations locating at regions of contact to other subspecies groups (in Amur, Kirghizia–Kazakhstan, and Iran) show divergence from central population by nuclear and mitochondrial markers. In Amur, gene flow from minor group could be detected based on the existence of private minor alleles in the major population. In Kirghizia and Kazakhstan, the bokharensis and major groups share almost all the microsatellite alleles detected though frequencies differ. In Iran, three geographically close populations are distinct according to the mitochondrial sequences but also indications of present or recent admixture is detected. Populations, which have expanded to regions previously unoccupied by the species (northern UK and Finland), show divergence only by one of the markers. The variability in molecular differentiation may be due to dissimilar expansions, depending on whether the colonized regions have previously been occupied by another subspecies or not, on the amount of colonizing birds, and on the amount of past and present gene flow.  © 2007 The Linnean Society of London, Biological Journal of the Linnean Society , 2007, 90 , 201–210.     

Development and characterization of eight microsatellite markers in bullet tuna (Auxis rochei)

The bullet tuna (Auxis rochei) is a worldwide species of high commercial value in Spain. Nevertheless, little information is currently available about the genetic characteristics of wild A. rochei populations. In this survey, we have developed eight new microsatellites for the bullet tuna using an enriched genome library protocol. Primers were screened on a total of 78 individuals from three wild populations (Mediterranean, Atlantic, and Pacific), revealing seven to 27 alleles per locus with expected heterozygosities ranging from 0.63 to 0.97. These markers can be potentially useful tools for use in population genetic studies.     

The Crime of Manabozo

On the explanation here given of the nature of the trickster, as the projection in myth of the magical violator of taboo, the contradictory features he presents may be elucidated one by one. A secondary feature, hitherto ignored in the Algonkin trickster myth—namely, Manabozo's brother's death—is shown to conceal the ritual murder of a near-kinsman committed in order to obtain magical power for the benefit of the group.