Teratoid Tumors Derived from Mouse Embryos Grown in an Immunologically Privileged Site

Mouse early embryos and embryo fragments were transplanted into an immunologically privileged site, consisting of a glass cylinder previously implanted under the skin of adult mice in order to test their tumor producing potential, in allogeneic adult recipients. The highest yield of tumors was obtained upon transplantation of 6 1/2 day old embryos in toto. i.e., including the embryonic and extraembryonic areas. Histological examination showed teratomas composed of differentiated tissues derived from the three germ layers containing isolated foci of undifferentiated cells and nodules of trophoblast giant cells. Areas exhibiting the histological appearance of yolk sac carcinoma were also observed. Transplantation of the whole 6 1/2 day old egg cylinder, including the ectoplacental cone, and the isolated embryonic area produced a lower incidence of teratomas with a reduced variety of differentiated tissues. No yolk sac carcinoma was found in these grafts. The ectoplacental cone of 6 1/2 day embryos produced no tumors. Grafts of genital ridges from 12 1/2 day embryos gave rise to teratomas with well differentiated tissues of embryonic and extraembryonic origin. Areas ressembling yolk sac carcinoma were also observed. The life span of trophoblastic giant cells within the glass cylinder was significantly longer than in other experimental systems.     

Cladistic analysis of Reduviidae (Heteroptera: Cimicomorpha) based on morphological characters

Abstract.  With more than 6600 species worldwide, Reduviidae (Insecta: Heteroptera), or assassin bugs, form the second largest and one of the most diverse groups of true bugs. The poor condition of the higher-level classification of Reduviidae is reflected by the facts that different authors recognize between 21 and 32 subfamily-level names and that Reduviidae were never subjected to a rigorous cladistic analysis using an exemplar approach. In the present study, a cladistic analysis of higher-level taxa of Reduviidae based on 162 morphological characters and 75 ingroup and outgroup species is presented. Twenty-one subfamily-level taxa of Reduviidae were examined, accounting for 28 tribes. In addition to characters previously used for diagnosis in Reduviidae, information on recently published character complexes is used in the present analysis, supplemented with new character information gathered specifically for this project. Reduviidae are supported as a monophyletic group with Pachynomidae as their sister taxon. The major results of this study are the support of a sistergroup relationship of Hammacerinae with the remaining Reduviidae, the monophyly of the Phymatine Complex, the relatively basal position of Harpactorinae within Reduviidae as well as a novel hypothesis on the relationships within this group, and the sistergroup relationship of Ectrichodiinae + Tribelocephalinae and their placement in a clade that also contains Emesinae, Saicinae, and Visayanocorinae. The analysis further supports a clade formed by paraphyletic Salyavatinae + Sphaeridopinae, renders Vesciinae non-monophyletic, and demonstrates the polyphyly of Reduviinae. Pseudocetherinae are shown to group with some Reduviinae. Triatominae are supported as a monophyletic group and are nested among additional Reduviinae and Stenopodainae.     

Barcoding,molecular taxonomy,and exploration of the diversity of shrews (Soricomorpha: Soricidae) on Mount Nimba (Guinea)

We tested the efficiency of cytochrome oxidase I (COI)‐barcoding as a taxonomic tool to discriminate and identify sympatric shrew species on Mount Nimba (Guinea). We identified 148 specimens at the species level using morphological characters and comparison with type specimens, including several taxa from Mount Nimba. We identified ten morphospecies and tested aspects of genetic diversity and monophyly using genetic data from three mitochondrial (16S, cytochrome b, and COI) and one nuclear marker (the breast cancer gene, BRCA). Nine morphospecies were validated under the phylogenetic and genetic species concepts, including the recently diverged species Crocidura buettikoferi, Crocidura theresae, and Crocidura grandiceps. Under the same concepts, our analyses revealed the presence of two cryptic species amongst animals identified as Crocidura muricauda. We then tested the efficiency of barcoding thanks to commonly used phenetic methods, with the 148 specimens representing 11 potentially valid species based on morphological and molecular data. We show that COI‐barcoding is a powerful tool for shrew identification and can be used for taxonomic surveys. The comparison of genetic divergence values shows the presence of a barcoding gap (i.e. difference between the highest intraspecific and the lowest interspecific genetic divergence values). Given that only a few COI sequences are available for Afrotropical shrews, our work is an important step forward toward their enrichment. We also tested the efficiency of the three other sequenced markers and found that cytochrome b is as efficient as COI for barcoding shrews. © 2012 The Linnean Society of London, Zoological Journal of the Linnean Society, 2012, 166 , 672–687.     

Plant diversity positively affects short‐term soil carbon storage in experimental grasslands

Increasing atmospheric CO₂ concentration and related climate change have stimulated much interest in the potential of soils to sequester carbon. In ‘The Jena Experiment’, a managed grassland experiment on a former agricultural field, we investigated the link between plant diversity and soil carbon storage. The biodiversity gradient ranged from one to 60 species belonging to four functional groups. Stratified soil samples were taken to 30 cm depth from 86 plots in 2002, 2004 and 2006, and organic carbon contents were determined. Soil organic carbon stocks in 0–30 cm decreased from 7.3 kg C m^?2 in 2002 to 6.9 kg C m^?2 in 2004, but had recovered to 7.8 kg C m^?2 by 2006. During the first 2 years, carbon storage was limited to the top 5 cm of soil while below 10 cm depth, carbon was lost probably as short‐term effect of the land use change. After 4 years, carbon stocks significantly increased within the top 20 cm. More importantly, carbon storage significantly increased with sown species richness (log‐transformed) in all depth segments and even carbon losses were significantly smaller with higher species richness. Although increasing species diversity increased root biomass production, statistical analyses revealed that species diversity per se was more important than biomass production for changes in soil carbon. Below 20 cm depth, the presence of one functional group, tall herbs, significantly reduced carbon losses in the beginning of the experiment. Our analysis indicates that plant species richness and certain plant functional traits accelerate the build‐up of new carbon pools within 4 years. Additionally, higher plant diversity mitigated soil carbon losses in deeper horizons. This suggests that higher biodiversity might lead to higher soil carbon sequestration in the long‐term and therefore the conservation of biodiversity might play a role in greenhouse gas mitigation.     

New World biogeography and the evolution of polychromatism: evidence from the bee assassin genus Apiomerus (Heteroptera: Reduviidae: Harpactorinae)

The crassipes and pictipes species groups of Apiomerus Hahn together contain 12 species, many with high intraspecific chromatic variability, which represent the majority of Nearctic species in this New World assassin bug genus. Because of their geographical distribution and their varying degrees of polychromatism, these two species groups provide a unique opportunity to study the evolution of polychromatism and analyse relationships among areas of endemism in the Nearctic, as well as determine the boundary between the Nearctic and Neotropical regions. The results of a morphology based phylogenetic analysis allowed investigation of these questions while also determining relationships among the 12 species in the two species groups. The crassipes and pictipes species groups were each supported as monophyletic and as sister taxa. Apiomerus rufipennis (Fallou) was not included in the original concept of the crassipes species group, but is shown here to be a member of the group. Apiomerus barrocoloradoi Forero, Berniker & Szerlip, which had been hypothesized previously to belong to the pictipes species group, is excluded from this group. Intraspecific polychromatism for each species was identified as being present in one of three states: no polychromatism; limited polychromatism; or polychromatism as discrete colour morphs. Limited polychromatism was here found to be the ancestral state for Apiomerus, and species with discrete colour morphs are restricted to the crassipes and pictipes species groups. Polychromatism appears to be a greatly homoplastic character within the genus. A Brooks parsimony analysis recovered distinct Nearctic and Neotropical clades. The Nearctic clade is divided between areas in the central and eastern U.S.A. and areas in the Western U.S.A. and Mexico. The Nearctic–Neotropical boundary for the taxa included in the analysis is along the Isthmus of Tehuantepec in southern Mexico.     

Internode Length in Pisum: the Response of le na Scions Grafted to Na Stocks

The recessive gene na results in peas with extremely short internodes(phenotype nana). In intact plants, na prevents expression ofthe Le/le gene pair which determine the tall/dwarf difference.na blocks a step early in the gibberellin biosynthetic pathwaywhile le prevents conversion of gibberellin A₂₀ to GA₁. Whengrafted to leafy Na stocks, le na and Le na scions become phenotypicallydwarf and tall, respectively. Hence, Na stocks provide a graft-transmissiblesubstance which promotes elongation of na scions and allowsexpression of the Le/le difference. Pisum, internode length, grafting, genotype     

Molecular and morphometric variation in two sibling species of the genus Praomys (Rodentia: Muridae): implications for biogeography

The rodent genus Praomys is widely distributed in the African tropics. The species are cryptic, rendering the species taxonomy unclear. There are differences of opinion concerning the specific status of Praomys misonnei and Praomys tullbergi, and their geographical distribution. We sequenced the cytochrome b and/or the 16S gene of 221 specimens from 12 countries in order to evaluate the genetic variability within these two species, and to precisely determine their geographical distribution. Morphological and morphometrical analyses on the sequenced specimens were also performed to find criteria useful for the identification of museum specimens. Our results confirm that P. misonnei and P. tullbergi are two valid species that can be separated by molecular data. However, no single discrete morphological character or simple metric measurement can be used to discriminate them. The percentage of misclassified individuals in multivariate discriminant analysis is relatively high (10%). The two species have allopatric distributions: P. tullbergi occurs in West Africa, from eastern Guinea to western Ghana, and P. misonnei is widely distributed from eastern Ghana to western Kenya. Within P. misonnei we identified three or four major geographical clades: a West Central African clade, an East African clade, a Nigerian clade, and a possible West African clade. Within P. misonnei, high geographical morphometrical variability was also identified. The role of both rivers and Pleistocene forest refugia in promoting speciation within the genus Praomys is discussed. © 2010 The Linnean Society of London, Zoological Journal of the Linnean Society, 2010, 160 , 397–419.     

Activities of Various Peptidases in the First Leaf of Wheat

In the first leaf of wheat (Triticum aestivum L. cv. Capelle) the content of soluble protein diminished to about 50% of the initial value between the 7th and the 19th day after sowing. In order to understand proteolysis in the leaves, the activities of several peptidases were measured in extracts from leaves at four different ages. The carboxypeptidase activities increased during the growth of the leaves, and then began to decrease. The activities of the alkaline peptidases increased, while that of the benzoyl-DL-arginine-p-nitroanilide (BAPA) hydrolysing enzyme decreased during the whole period studied. The “naphthylamidase” activities showed first a slow rise, but then leveled off. Two bands with naphthylamidase activity could be detected after disc electrophoresis. All the peptidases studied were present in the leaves at rather high concentrations. This indicates that they all may participate in the hydrolysis of leaf proteins into free amino acids.