Expression of nucleosomal protein HMGN1 in the cycling mouse hair follicle

Here we examine the expression pattern of HMGN1, a nucleosome binding protein that affects chromatin structure and activity, in the hair follicle and test whether loss of HMGN1 affects the development or cycling of the follicle. We find that at the onset of hair follicle development, HMGN1 protein is expressed in the epidermal placode and in aggregated dermal fibroblasts. In the adult hair follicle, HMGN1 is specifically expressed in the basal layer of epidermis, in the outer root sheath, in the hair bulb, but not in the inner root sheath and hair shaft. The expression pattern of HMGN1 is very similar to p63, suggesting a role for HMGN1 in the transiently amplifying cells. We also find HMGN1 expression in some, but not all hair follicle stem cells as detected by its colocalization with Nestin and with BrdU label-retaining cells. The appearance of the skin and hair follicle of Hmgn1^?/? mice was indistinguishable from that of their Hmgn1^+/+ littermates. We found that in the hair follicle the expression of HMGN2 is very similar to HMGN1 suggesting functional redundancy between these closely related HMGN variants.     

Evaluation of LEXF/FXLE rat recombinant inbred strains for genetic dissection of complex traits.

Recombinant inbred (RI) strains are formed from an outcross between two well-characterized inbred stains followed by at least 20 generations of inbreeding. RI strains can be utilized for the analysis of many complex phenotypic traits. The LEXF/FXLE RI strain set consists of 34 RI strains derived by reciprocal crossing of LE/Stm and F344/Stm. Here we report on genetic dissections of complex traits using this RI set and their parental strains. We have developed strain distribution patterns for 232 informative simple sequence length polymorphism markers. The framework map covers the rat genome except for chromosome Y. Seventy-six phenotype parameters, which included physiological and behavioral traits, were examined for these RI lines. Quantitative trait locus (QTL) analysis of these parameters revealed 27 significant and 91 suggestive QTLs, illustrating the potential of this RI resource for the detection of underlying gene functions for various phenotypes. Although this RI set was originally developed to study susceptibility to chemical-induced tumors, it has been shown to be equally powerful for a wide spectrum of traits. The LEXF/FXLE RI strains have been deposited at the National Bio Resource Project for the Rat in Japan and are maintained under specific pathogen-free conditions. They are available at http://www.anim.med.kyoto-u.ac.jp/nbr.     

Some characteristics of the two types of A-cells in the islets of Langerhans of guinea-pigs

Summary Two types of A cells were identified in the islets of Langerhans of guinea-pigs. The silver-positive A₁ cells were found to correspond to the C cells previously described by some authors in this species. The most conspicuous feature of the A₂ cells was their strongly luminescent granulation in dark field illumination and intense staining with ponceaufuchsin or phloxine. The nuclei of the A₁ cells were smaller than those of the A₂ cells, while no significant differences were found for their nuclear eccentricities. The previous hypothesis, that the A₂ cells are the source of glucagon, obtained support from the finding that this type of A cell was distinctly tryptophane positive. A great susceptibility to cobalt is probably another characteristic property for the A₂ cells in the guinea-pig.This investigation was supported by research grant A-5759 from the National Institute of Arthritis and Metabolic Diseases, United States Public Health Service and by Svenska Sällskapet för Medicinsk Forskning.     

Correlation between the Paleocene/Eocene boundary and the Ilerdian at Campo, Spain

The Ilerdian is a well-established Tethyan marine stage, which corresponds to an important phase in the evolution of larger foraminifera not represented in the type-area of the classical Northwest-European stages. This biostratigraphic restudy of its parastratotype in the Campo Section (northeastern Spain) based on planktic foraminifera, calcareous nannofossils, dinoflagellate cysts and the distribution of the stable isotopes ∂¹³C and ∂¹⁸O is an attempt to correlate the Paleocene/Eocene boundary based on a characteristic carbon isotope excursion (CIE) marking the onset of the Initial Eocene Thermal Maximum (IETM) and the Ilerdian stage. The base of this ∂¹³C excursion has been chosen as the criterion for the recent proposal of the Global Stratotype Section and Point (GSSP) of the base of the Eocene (= base of the Ypresian) in the Dababiya Section (Egypt) to which an age of 54.9 Ma has been attributed. This level is also characterized by a marked extinction among the deep-water benthic foraminifera (Benthic Foraminifera Extinction Event, BFEE), a flood of representatives of the planktic foraminiferal genus Acarinina and the acme of dinoflagellate cysts of the genus Apectodinium. In the Campo Section, detailed biozonations (planktic foraminifera, calcareous nannofossils, dinoflagellate cysts) are recognized in the Lower and Middle Ilerdian. The correlation with the Ypresian stratotype is based on dinoflagellate cysts and calcareous nannofossils. The base of the Ilerdian is poor in planktic microfossils and its precise correlation with the redefined Paleocene/Eocene boundary remains uncertain.     

Molecular Phylogeny of Conjugating Green Algae (Zygnemophyceae,Streptophyta) Inferred from SSU rDNA Sequence Comparisons

Nuclear-encoded SSU rDNA sequences have been obtained from 64 strains of conjugating green algae (Zygnemophyceae, Streptophyta, Viridiplantae). Molecular phylogenetic analyses of 90 SSU rDNA sequences of Viridiplantae (inciuding 78 from the Zygnemophyceae) were performed using complex evolutionary models and maximum likelihood, distance, and maximum parsimony methods. The significance of the results was tested by bootstrap analyses, deletion of long-branch taxa, relative rate tests, and Kishino-Hasegawa tests with user-defined trees. All results support the monophyly of the class Zygnemophyceae and of the order Desmidiales. The second order, Zygnematales, forms a series of early-branching clades in paraphyletic succession, with the two traditional families Mesotaeniaceae and Zygnemataceae not recovered as lineages. Instead, a long-branch Spirogyra/Sirogonium clade and the later-diverging Netrium and Roya clades represent independent clades. Within the order Desmidiales, the families Gonatozygaceae and Closteriaceae are monophyletic, whereas the Peniaceae (represented only by Penium margaritaceum) and the Desmidiaceae represent a single weakly supported lineage. Within the Desmidiaceae short internal branches and varying rates of sequence evolution among taxa reduce the phylogenetic resolution significantly. The SSU rDNA-based phylogeny is largely congruent with a published analysis of the rbcL phylogeny of the Zygnemophyceae (McCourt et al. 2000) and is also in general agreement with classification schemes based on cell wall ultrastructure. The extended taxon sampling at the subgenus level provides solid evidence that many genera in the Zygnemophyceae are not monophyletic and that the genus concept in the group needs to be revised.     

Photoinhibition of Photosystem I in field-grown barley (Hordeum vulgare L.): Induction, recovery and acclimation

The effects of exposure of a field-grown winter cultivar of barley (Hordeum vulgare L.) to Photosystem I (PS I) photoinhibitory conditions in the form of bright day-light combined with chilling conditions were investigated. PS I photoinhibition was manifested by damage to the Fe-S centers of PS I and to the PS I-A/B polypeptides. Up to 20% of the PS I complexes were photoinactivated. Upon transfer to room temperature, the plants partially recovered from PS I photoinhibition, although damage was still detectable after one week. These results demonstrate that PS I photoinhibition is a physiologically relevant phenomenon in chilling-tolerant plants grown under field conditions. In order to study the induction of cyclic electron transport around PS I by PS I photoinhibitory conditions, antibodies raised against the NDH-I subunit of the NDH complex (a component of cyclic electron transport) were used to measure NDH levels in the exposed plants. A marked increase in the amount of NDH complex and a corresponding increase in NADPH dehydrogenase activity in the thylakoids were observed. The data indicate that the response to PS I-photoinhibitory conditions may involve regulated changes in cyclic electron transport around PS I. This revised version was published online in June 2006 with corrections to the Cover Date.     

Intimate roles for cyanogenic glucosides in the life cycle of Zygaena filipendulae (Lepidoptera, Zygaenidae)

Zygaena larvae sequester the cyanogenic glucosides (CNglcs) linamarin and lotaustralin from their food plants (Fabaceae) and also de novo biosynthesize these compounds. In Zygaenidae, CNglcs serve as defence compounds during the entire life cycle, and their content and ratio are tightly regulated. We demonstrate that Z. filipendulae males transfer a nuptial gift of CNglcs to females during mating, and that females prefer males with a higher content of CNglcs for mating. Average HCN emission from female imagines is 19 times higher than from males, suggesting that plumes of HCN emitted from the perching female may serve to attract flying males. Analysis of the linamarin and lotaustralin content and ratio within different tissues in Z. filipendulae larvae shows that integument and haemolymph constitute the main sites of CNglc deposition. The data suggest that CNglcs may serve an additional role as storage compounds of reduced nitrogen that is mobilized during the transition of the last instar larva to imago, most likely to provide nitrogen for chitin synthesis. At least one of the enzymes responsible for de novo biosynthesis of CNglcs in Z. filipendulae is located in the integument. In conclusion, CNglcs play many important and different roles during the entire life cycle of Z. filipendulae in addition to defence.     

Loricifera from the deep sea at the Galápagos Spreading Center,with a description of <Emphasis Type="Italic">Spinoloricus turbatio</Emphasis> gen. et sp. nov. (Nanaloricidae)

Specimens of a new species of Loricifera, Spinoloricus turbatio gen. et sp. nov., have been collected at the Galápagos Spreading Center (GSC) during the cruise SO 158, which is a part of the MEGAPRINT project. The new genus is positioned in the family Nanaloricidae together with the three already described genera Nanaloricus, Armorloricus and Phoeniciloricus. The postlarvae and adults of Spinoloricus turbatio gen. et sp. nov. are characterized by a mouth cone with eight oral ridges and basally with a cuticular reinforcement named mouth cone pleat; eighth row with 30 whip-like spinoscalids and 30 “alternating” plates; thorax with eight single and seven double trichoscalids, where the single trichoscalids are twice the length of the double ones, and the secondary appendage on the double trichoscalid is smooth whereas the others are serrated; lorica with eight cuticular plates with additional spikes in the anterior corners and intercalary plicae between the plates. Some of these genus-specific characters such as the mouth cone pleat, the “alternating” plates and the intercalary plicae have not been observed in Nanaloricidae before. The Higgins-larvae of Spinoloricus turbatio gen. et sp. nov. are characterized by six rectangular plates in the seventh row with two teeth, an indistinct honeycomb sculpture and long toes with little mucrones. The SO 158 cruise has yielded a minimum of ten new species of Loricifera out of only 42 specimens. These new species belong to two different orders, where one being new to science, and three different families. This result indicates a high diversity of loriciferans at the GSC. Nearly all the collected loriciferans are in a moulting stage, hence there is a new stage inside the present stage. This prolongation of life stages and the occurrence of multiple life stages inside each other are typical of deep-sea loriciferans. Here exemplified by the two postlarvae with adults inside, which is observed for the first time in Nanaloricidae.