Ecomorphology of a generalist freshwater gastropod: complex relations of shell morphology,habitat, and fecundity

Evolutionary and ecological situations in a species’ native and invasive ranges can be drastically different. This is the case for Potamopyrgus antipodarum Gray (1843) a morphologically highly variable freshwater snail native to New Zealand, where sexual and asexual individuals coexist and experience selective pressure by sterilizing endoparasites. By contrast, only a few asexual lineages have been established in invaded regions around the globe, where parasite infection is extremely rare. We analyzed the ecomorphology of 996 native P. antipodarum in a geometric morphometric framework, using brood size as proxy for fecundity, and mtDNA and nuclear SNPs to account for relatedness and identify reproductive mode. As expected, we found genetic and morphological diversity to be higher in native than in invasive snails investigated previously, but surprisingly no higher morphological diversity in sexual versus asexual individuals. The relationships between shell morphology, habitat, and fecundity were complex. Shape variation was primarily linked to genetic relatedness but specific environmental factors including flow rate induced similar shell shapes. By contrast, shell size was largely explained by environmental factors. Fecundity was correlated with size but showed trade-offs with shape in increasingly extreme conditions. With increasing flow and toward small springs, the trend of shell shape becoming wider was reversed, i.e., snails with narrower shells were brooding more embryos. We concluded that both genetic and environmental contributions to variation in shell morphology in P. antipodarum likely play an important role in the ability of this species to adapt to a wide spectrum of habitats.     

Treatment of poor-risk myelodysplastic syndromes and acute myeloid leukemia with a combination of 5-azacytidine and valproic acid

5-azacytidine (AZA) has become standard treatment for patients with higher-risk myelodysplastic syndrome (MDS). Response rate is about 50% and response duration is limited. Histone deactylase (HDAC) inhibitors are attractive partners for epigenetic combination therapy. We treated 24 patients with AZA (100?mg/m(2), 5?days) plus valproate (VPA; continuous dosing, trough serum level 80-110?μg/ml). According to WHO classification, 5 patients had MDS, 2 had MDS/MPD, and 17 had acute myeloid leukemia (AML). Seven patients (29%) had previously received intensive chemotherapy, and five had previous HDAC inhibitor treatment. The overall response rate was 37% in the entire cohort but significantly higher (57%) in previously untreated patients, especially those with MDS (64%). Seven (29%) patients achieved CR (29%) and two PR (8%), respectively. Hematological CR was accompanied by complete cytogenetic remission according to conventional cytogenetics in all evaluable cases. Some patients also showed complete remission according to FISH on bone marrow mononuclear cells and CD34(+) peripheral blood cells, as well as by follow-up of somatic mitochondrial DNA mutations. Four additional patients achieved at least marrow remissions. Factors influencing response were AML (vs. MDS), marrow blast count, pretreatment, transfusion dependency, concomitant medication with hydroxyurea, and valproic acid (VPA) serum level. This trial is the first to assess the combination of AZA plus VPA without additional ATRA. A comparatively good CR rate, relatively short time to response, and the influence of VPA serum levels on response suggest that VPA provided substantial additional benefit. However, the importance of HDAC inhibitors in epigenetic combination therapy can only be proven by randomized trials.     

Enhanced contact allergen- and UVB-induced keratinocyte apoptosis in the absence of CD95/Fas/Apo-1

FAS/CD95/Apo-1 is a ubiquitously expressed cell-surface receptor involved in the initiation of programmed cell death. Its function in epidermal keratinocytes has been incompletely defined. Available evidence from in vitro studies points to important roles of Fas in the pathogenesis of contact dermatitis and in keratinocyte apoptosis induced by ultraviolet light. To define functions of Fas in the epidermis in vivo, we have generated mice with epidermis-specific deletion of the fas gene and tested its requirement for 2,4-dinitrofluorobenzene-induced contact dermatitis and for ultraviolet light B (UVB)-induced keratinocyte apoptosis. We report here our unexpected finding that keratinocyte apoptosis induced by both a contact allergen and UVB irradiation was significantly enhanced in Fas-negative epidermis. Expression of Fas by epidermal keratinocytes was neither necessary for the normal development of contact hypersensitivity of the skin, nor required for keratinocyte apoptosis following UVB irradiation. Our study results thus show that in the epidermis in vivo Fas exerts antiapoptotic effects that outweigh its proapoptotic role in contact hypersensitivity responses of the skin and in the tissue response of the epidermis to UVB irradiation.     

A new Georissa (Gastropoda: Neritopsina: Hydrocenidae) from a limestone cave in Malaysian Borneo

In a previous paper, we have reported on a new, troglobiticspecies of Georissa and its possible parapatric origin fromGeorissa saulae Benthem-Jutting, 1966, which occurs outsidethe cave system of Batu Sanaron, a limestone outcrop in Sabah,Malaysian Borneo. These analyses were based on genetic and morphometricdata. Here, we formally describe the new species adding anatomicaldata derived from dissections and histological serial sectionsas well as fine structural data of shell, operculum and radula,and compare it with its stem species. The two species differin shell and radular morphology as well as genital characters.Since we found anatomical differences between very closely relatedspecies, we assume that dissections would be of general usefor the taxonomy of Georissa and the remaining nominal genus-grouptaxa of the poorly known Hydrocenidae.     

Allozymic differentiation in the land snail Arianta arbustorum (Stylommatophora, Helicidae): historical inferences

The intraspecific genetic differentiation depends to a large part on historical factors. The mode of dispersal is an important determinant of the genetic diversity especially of newly founded populations. Fast long-distance colonization of formerly unsuitable habitats results in reduced genetic diversity and lineages originating from different glacial refugia form well-defined hybrid zones, where they meet. Slow dispersers, on the other hand, preserve their refugial genetic diversity. Paleontological findings and a previous analysis of mtDNA suggest that the land snail Arianta arbustorum, which today is widely spread across Europe, has survived the Pleistocene glaciations within the boundaries of permafrost. In the present paper, we asked, whether the differentiation of nuclear markers, i.e. allozymes, supports these results. We investigated the allozymic differentiation at 15 polymorphic loci in 14 Alpine and one English populations of the land snail A. arbustorum. Various tests of genetic population differentiation yielded ambiguous results. Allele frequencies differed significantly across populations and all but five pairwise F_ST values were significant. Genetic distances between populations were comparatively high. On the other hand, an exact test of population differentiation found no differences and the assignment of individuals to their populations of origin was poor. This indicates that allozymic differentiation is constrained. Whether these constraints are of natural or methodological nature remains open. Matrices of genetic and geographical distances were correlated only after removal of the English population from the analysis. Similarly, with one exception F_ST values increased as the number of regions included in the calculations increased. Thus, on a regional scale, we largely observed a pattern of isolation by distance, which does no longer hold on a larger scale. This is well in accordance with the previous findings based on mtDNA. Mitochondrial lineages were widely distributed across Europe and overlapped extensively. Considering the low potential for dispersal of a land snail, the patchy distribution of lineages, and the high genetic diversity also found in the present study suggests that A. arbustorum has survived the Pleistocene within the boundaries of permafrost.     

Spondylitis in a humpback whale (Megaptera novaeangliae) from the southeast Pacific

A 7.25 m long male humpback whale (Megaptera novaeangliae) with spondylitis was found beached on August 13, 1994 at Ancon, Ecuador (2 degrees 23' S, 80 degrees 47' W). The condition involved at least 11 vertebrae, 7 lumbar (L4 to L11) and 4 caudal (Ca1 to Ca4). Partial fusion of vertebrae was observed as a result of intervertebral bony proliferation, likely impeding full motion. The relatively young age of this specimen and the severity of the deformities suggest an infectious, rather than degenerative, process. The gross findings are most consistent with some type of spondyloarthritis. Although this condition has previously been identified in a number of cetacean species, the pathogenesis, population impact and ecologic implications have not been fully assessed. This is the third case described for humpback whales and the first for a humpback whale from the SE Pacific.     

First set of microsatellite markers for genetic characterization of the Eurasian beaver (Castor fiber) based on tissue and hair samples

Noninvasive genetic techniques have become indispensible tools in wildlife conservation and management. Here, we report the development of the first set of microsatellite markers for the Eurasian beaver (Castor fiber). All 15 loci show considerable variation within the sampled region in southwestern Germany, with number of alleles ranging from two to six alleles per locus. A comparison between tissue and hair samples revealed that amplification success was only slightly lower for hair samples, making their use in noninvasive monitoring feasible. Despite some evidence for false alleles and allelic dropout, 77% of all loci were genotyped successfully among all hair samples and loci tested. The developed markers will be used for subspecies differentiation and reconstruction of dispersal routes, following reintroductions in Central Europe.