Reassessing Neotropical angiosperm distribution patterns based on monographic data: a geometric interpolation approach

Monographic data rely on specimens deposited in herbaria and museums, which have been thoroughly revised by experts. However, monographic data have been rarely used to map species richness at large scale, mainly because of the difficulties caused by spatially heterogeneous sampling effort. In this paper we estimate patterns of species richness and narrow endemism, based on monographic data of 4,055 Neotropical angiosperm species. We propose a geometric interpolation method to derive species ranges at a 1° grid resolution. To this we apply an inverse distance-weighted summation scheme to derive maps of species richness and endemism. In the latter we also adjust for heterogeneous sampling effort. Finally, we test the robustness of the interpolated species ranges and derived species richness by applying the same method but using a leave-one-out-cross-validation (LOOCV). The derived map shows four distinct regions of elevated species richness: (1) Central America, (2) the Northern Andes, (3) Amazonia and (4) the Brazilian Atlantic coast (‘Mata Atlantica’). The region with the highest estimated species richness is Amazonia, with Central America following closely behind. Centers of narrow endemism are located over the entire Neotropics, several of them coinciding with regions of elevated species richness. Sampling effort has a minor influence on the interpolation of overall species richness, but it substantially influences the estimation of regions of narrow endemism. Thus, in order to improve maps of narrow endemism and resulting conservation efforts, more collection and identification activity is required.     

Cytogenetic analysis of mouse metaphase II oocytes following exposure to tritiated water

Female mice were given different dosages (0, 3.0, 7.5, 15.0, or 30 muCi/ml) of tritium in their drinking water continuously from 3 to 7 weeks of age to assess the effects on germ cell chromosomes. At 8-9 weeks of age, mice were superovulated and metaphase II oocytes were processed and C-banded for cytogenetic analyses. Chromatid acentric fragments were the only type of structural aberration detected, and their incidence was higher in controls than in any of the tritiated water (HTO) groups. Analysis of numerical chromosomal aberrations revealed that the incidence of hypoploid (N = 19) oocytes was higher in oocytes from mice who drank HTO as compared with controls. However, the effects of HTO upon aneuploidy induction was not definitive due to the increase the incidence of aberrations in mouse oocytes can be related to the low dose rate resulting from chronic HTO exposure and possibly death of tritium-damaged cells.     

Seasonal variation in food allergy to apple

The aim of the study was to investigate the possibility of a seasonal variation in reactivity to apples in 27 birch pollen allergic patients. Before and during the birch pollen season 1998, the patients were subjected to double-blind, placebo-controlled food challenges (DBPCFCs) with grated fresh Golden Delicious apple followed by an open food challenge with whole fresh apple. The clinical reactions elicited during the challenges were evaluated both by the patients and the investigators. Moreover, the skin reactivity and the in vitro reactivity to apple were evaluated by skin prick test (SPT), leukocyte histamine release (HR), measurement of specific IgE, and immunoblotting experiments. The sensitivity of the DBPCFC, when compared with the result of the open challenge, was 0.74 (14/19) before the season and 0.80 (16/20) during the season. None of the patients reacted to the blinded challenge without a subsequent reaction to the open challenge. One placebo reaction was registered both before and in season, but not in the same patient. The patient scores of the first positive challenges, and the maximal scores of each combined blinded and open challenge session, were significantly increased during the pollen season (P<0.05). The scores of the open challenge were significantly higher than the scores of the DBPCFC both before the season and during the in-season challenges (P<0.05). Specific IgE against Golden Delicious increased during season (P<0.05), while neither SPT, HR, nor immunoblotting experiments could confirm an increase in reactivity. In conclusion, the results of the oral challenge tests indicated an increase in clinical reactivity to apples during the birch pollen season in birch pollen allergic individuals.     

Vegetation,land use and management of the inner-dune zone in the North-Holland Dune Reserve,The Netherlands

The inner-dune zone between the villages of Bakkum and Egmond in the North-Holland Dune Reserve is one of the few remaining examples of the semi-natural boundary between the dunes and the polders. For several centuries this area has been used for various purposes, in particular for grazing. Large-scale excavating, especially after about 1900, has encroached upon the dunes. Vegetation and land-use history were studied and a provisional scheme on the vegetation development is presented. Management policies discussed are non-intervention, mowing in order to start natural processes such as rabbit grazing, and the continuation of traditional livestock grazing. Proposals for external management policies were made in order to maintain or enhance the original transition zone, based on comprehensive physical-geographical studies of the whole inner-dune zone.     

Novel α-L-Fucosidases from a Soil Metagenome for Production of Fucosylated Human Milk Oligosaccharides

This paper describes the discovery of novel α-L-fucosidases and evaluation of their potential to catalyse the transglycosylation reaction leading to production of fucosylated human milk oligosaccharides. Seven novel α-L-fucosidase-encoding genes were identified by functional screening of a soil-derived metagenome library and expressed in E. coli as recombinant 6xHis-tagged proteins. All seven fucosidases belong to glycosyl hydrolase family 29 (GH 29). Six of the seven α-L-fucosidases were substrate-inhibited, moderately thermostable and most hydrolytically active in the pH range 6–7, when tested with para-nitrophenyl-α-L-fucopyranoside (pNP-Fuc) as the substrate. In contrast, one fucosidase (Mfuc6) exhibited a high pH optimum and an unusual sigmoidal kinetics towards pNP-Fuc substrate. When tested for trans-fucosylation activity using pNP-Fuc as donor, most of the enzymes were able to transfer fucose to pNP-Fuc (self-condensation) or to lactose. With the α-L-fucosidase from Thermotoga maritima and the metagenome-derived Mfuc5, different fucosyllactose variants including the principal fucosylated HMO 2’-fucosyllactose were synthesised in yields of up to ~6.4%. Mfuc5 was able to release fucose from xyloglucan and could also use it as a fucosyl-donor for synthesis of fucosyllactose. This is the first study describing the use of glycosyl hydrolases for the synthesis of genuine fucosylated human milk oligosaccharides.     

Linking micromorphism,brooding, and hermaphroditism in brachiopods: Insights from Caribbean Argyrotheca (Brachiopoda)

In extant brachiopods, parental brooding of the larvae occurs exclusively within Rhynchonelliformea. Methods of larval protection range from simple retention of the larvae within the mantle cavity, to sophisticated brood care within highly specialized brood pouches found in Argyrotheca and Joania (Terebratulida, Megathyridoidea), Gwynia (Terebratulida, Gwynioidea), and all Thecideoidea (Thecideida). Previous studies on the reproductive biology of Argyrotheca yielded contrasting results on the epithelial origin of the brood pouches in this genus. Here, representatives of different species of Argyrotheca from the Belize Barrier Reef were examined using histological section series. Brood pouches of four species, A. cf. schrammi and Argyrotheca sp. 1–3, are of the same basic structure, formed by invaginations of the anterior body wall and connected to the visceral cavity via the metanephridia. The same four species are simultaneously hermaphroditic, suggesting that fertilization is achieved, at least partly, through selfing. One species, Argyrotheca rubrocostata, differs significantly from all others as it has no brood pouch and gonochoric gonads. Thus, the presence of brood pouches and simultaneous hermaphroditism are concluded to be correlated within Megathyridoidea and proposed to be homologous traits of Joania and several but not all species of Argyrotheca, questioning the monophyletic status of both genera. In contrast to the brood pouches of Thecideoidea, lophophoral epithelium is not involved in the formation of the pouches of Argyrotheca and Joania. Therefore, megathyridoid and thecideoid brood pouches are not homologous but evolved independently within rhynchonelliform brachiopods. All brachiopods with brood pouches share a micromorphic form and a short life span, limiting the space and time available for gamete and larval development. We suggest that the brood pouches and the hermaphroditic gonads of Argyrotheca spp. and Joania compensate these limitations by minimizing the loss of gametes and larvae, and by maximizing the chances of successful fertilization. J. Morphol., 2013. © 2013 Wiley Periodicals, Inc.     

Enantioselective hydrolysis of esters of secondary alcohols using lyophilized Bakers'' yeast

A number of acetoxycarboxylic acid esters were hydrolysed enantioselectively by Saccharomyces cerevisiae Hansen leading to chiral hydroxycarboxylic acid esters of high optical purity. The scope and limitations of this method with respect to the substitutional pattern of substrates were investigated. Subcellular localization of the hydrolytic activity on the plasma membrane led to the assumption that unspecific carboxyl esterases are responsible for hydrolysis of this type of substrate. Comparative experiments using viable cells and lyophilized cells as source of enzyme revealed the latter to be superior with respect to enantioselection and ease of handling.     

From DNA transcription to visible structure: What the development of multicellular animals teaches us

This article is concerned with the problem of the relation between the genetic information contained in the DNA and the emergence of visible structure in multicellular animals. The answer is sought in a reappraisal of the data of experimental embryology, considering molecular, cellular and organismal aspects. The presence of specific molecules only confers a tissue identity on the cells when their concentration exceeds the 'threshold of differentiation'. When this condition is not fulfilled the activity of the genes that code for the specific molecules in question only confers on them a histogenetic potency, i.e. the capacity to form the corresponding tissue in further development (or to trans-differentiate to that tissue). The progressive restriction of histogenetic potencies during development reflects the irreversible repression of more and more genes. The establishment of a given tissue identity under the influence of an inducing tissue (or a morphogenetic hormone) is only possible when the cells have acquired the competence to respond. Tissue differentiation proceeds progressively during development thanks to the cytoplasmic 'memory' that cells retain collectively (or sometimes individually) of the items of information successively registered by their ancestors cells. The increasing complexity of visible structure emerging during development results only from the progression of tissue differentiation. This involves continual exchange of information among the cells and leads to (1) cell displacements and rearrangements, particularly during organogenesis and (2) extreme diversification of cell individualities within tissues, particularly during postembryonic growth. A mutation (just as a teratogenic factor) evokes an anomaly that is localized in both space and time because it alters a certain aspect of cell behaviour (particularly cell surface adhesiveness or mitotic activity) at the time when this is involved in the establishment of a particular structural trait. Neither the organization of the adult nor the modalities of development are encoded in the DNA. The automatic concatenation of cell interactions in the embryo and the structural amplification it entails is conditioned by the specific biochemical composition of the cytoplasm of the egg and by the heterogeneous distribution of its inclusions.