Species associations and nurse plant effects in patches of high-Andean vegetation

Abstract. In high-elevation communities of the southern Andes, plant cover is low due to severe environmental conditions and vegetation occurs mostly as isolated small (< 1 m²⁾ patches. Most patches are dominated by flat cushion plants. We evaluated patterns of plant species co-occurrence and species affinity for patches with and without cushion plants and different species richness. We mapped and recorded species composition of patches occurring within two 20 m × 20 m plots at the NE slope of Cerro Chall-Huaco, Nahuel Huapi National Park, Argentina. In these plots, we identified 32 and 24 plant species, and a maximum of 15 and 12 species per patch, respectively. The community was characterized by positive associations between species. Patches in which either of the common cushion plants Mulinum leptacanthum and Oreopolus glacialis occurred sustained richer communities than patches in which they were absent. Patches dominated by different cushion plants did not differ in species composition, but species differed in their affinities for patches with different numbers of species. Because richness increased with patch size and patch size with time, differential affinities of plant species suggest that successional changes take place in the patches. Some small herbaceous species appear to act as late colonizers, mostly restricted to species-rich patches. Flat cushion plants are considered ‘nurse plants’; they strongly modify micro-environmental conditions and allow establishment and survival of associated species.     

cDNA cloning of 15-lipoxygenase type 2 and 12-lipoxygenases of bovine corneal epithelium1

Bovine corneal epithelium contains arachidonate 12- and 15-lipoxygenase activity, while human corneal epithelium contains only 15-lipoxygenase activity. Our purpose was to identify the corneal 12- and 15-lipoxygenase isozymes. We used cDNA cloning to isolate the amino acid coding nucleotide sequences of two bovine lipoxygenases. The translated sequence of one lipoxygenase was 82% identical with human 15-lipoxygenase type 2 and 75% identical with mouse 8-lipoxygenase, whereas the other translated nucleotide sequence was 87% identical with human 12-lipoxygenase of the platelet type. Expression of 15-lipoxygenase type 2 and platelet type 12-lipoxygenase mRNAs were detected by Northern analysis. In addition to these two lipoxygenases, 12-lipoxygenase of leukocyte (tracheal) type was detected by polymerase chain reaction (PCR), sequencing, and Northern analysis. Finally, PCR and sequencing suggested that human corneal epithelium contains 15-lipoxygenase types 1 and 2.     

Gorilla RH-like genes and antigens

 It has been previously shown that most of the human IgG monoclonal D-specific antibodies define a polymorphism in the gorilla consisting of two phenotypes: D^gor-positive and D^gor-negative. By quantitative indirect immunofluorescence assay and quantitative immunoblotting it was evaluated that the number of D^gor antigenic sites per gorilla red cell varies from a level equivalent to that observed for human RhD-positive cells to a level eight times higher. By immunoblotting with a rabbit reagent specific for the carboxylic end of human Rh-polypeptides it was demonstrated that RBCs from all gorillas, whatever their D^gor phenotype, possess 33000 relative molecular mass Rh-like polypeptides. The expression of the D^gor antigen was shown to be associated with the presence of three polymorphic bands defined by Southern blot using a human exon 4 RHCE probe, and to a length polymorphism of gorilla intron 3 evidenced by polymerase chain reaction. By contrast, the expression of the D^gor antigen was not associated to the length polymorphism of gorilla intron 4 which is related to the presence or absence of an Alu-Sx element in intron 4, paralleling the situation observed in human. These results confirmed the presence in the gorilla genome of at least two RH-like genes, one of which being responsible for D^gor polymorphism. The phylogenesis of the human and gorilla RH genes is discussed in light of the comparison of intron 4 sequences. Received: 23 March 1998 / Revised: 18 June 1998     

Funsulinid assemblages and facies of the Bombaso Fm. and basal meledis Fm. (Moscovian-Kasimovian) in the central Carnic Alps (Austria/Italy)

Summary The Bombaso Formation and basal Meledis Formation in the central Carnic Alps near Straniger Alm and Zollnersee (Austria/Italy) unconformably overlie the folded Variscan basement and consist of shallow marine clastic and carbonate sediments which are arranged to form two fining and deepening upward sequences. Particularly limestones and even breccias of the Bombaso Formation yielded a rich fusulinid fauna composed of 34 species which are attributed to the following zones:Quasifusulinoides quasifusulinoides-Protriticites ovatus; Protriticites pseudomontiparus, andMontiparus montiparus. Breccias of the Bombaso Formation west of Straniger Alm contain the oldest fusulinid fauna of the Carnic Alps, belonging to theQuasifusulinoides quasifusulinoides —Protriticites ovatus zone. The fauna is composed ofQuasifusulinoides quasifusulinoides, Q. fallax, Q. intermedius, Protriticites cf.ovoides, andPr. ovatus. This assemblage is most similar to that of the Peskovskaya Formation of the Myachkovian Horizon in the Moscow Basin indicating uppermost Moscovian age. Limestones from depositional sequence 1 at Zollnersee also contain fusulinids of the uppermost Moscovian which are characterized by a more diverse assemblage:Schubertella donetzica, Fusiella lancetiformis, Beedeina ulitinensis, B. consobrina, B. nytvica, B. siviniensis, Quasifusulinoides pakhrensis, Q. fallax, Q. kljasmicus, Q. quasifusulinoides, Fusulinella rara, andProtriticites ovatus. Limestones and calcareous sandstones-siltstones of the basal Meledis Formation of depositional sequence 2 near Zollnersee and at Cima Val di Puartis are characterized by fusulinids of theProtriticites pseudomontiparus zone (Protriticites globulus, Pr. pseudomontiparus, Pr. sphaericus, Pr. rotundatus, Pr. ovoides, Pr. lamellosus, andPraeobsoletes burkemensis) and byMontiparus paramontiparus zone (Praeobsoletes pauper, P. burkemensis, Obsoletes timanicus, O. obsoletes, Montiparus paramontiparus, M. umbonoplicatus, M. montiparus, M. likharevi, M. rhombiformis andM. priscus) indicating lower to middle Kasimovian age (Krevyakinskian and Khamovnicheskian Horizons of the Russian Platform). In memoriam FranzKahler (1900–1995)     

Evidence for the recent dispersal of Sophora (Leguminosae) around the Southern Oceans: molecular data

Aim The aim is to use DNA sequence data to test between vicariance and long range dispersal (by floating seed-pods) explanations for the origin and range of the Edwardsia species of Sophora (Sophoreae: Papilionoideae: Leguminosae). Location This group is widely distributed around the South Pacific and into the South Atlantic on both continental fragments and oceanic islands. Methods DNA sequences from an intergene region (atpB-rbcL) of the chloroplast were determined for twelve taxa (including outgroups) and used to test these hypotheses. Sophora fossils were used to calibrate the evolutionary tree. Results The Edwardsia group of Sophora appears monophyletic and is well differentiated from other Sophora. However, the genetic difference between species within the South Pacific and to the South Atlantic is very low. Main conclusionsThe results eliminate vicariance explanations for this section of Sophora and strongly support an origin from other (non-Edwardsia) Sophora in the north-west Pacific. Dispersal appears initially to be to Tuvalu, Lord Howe Island, New Zealand, and subsequently across the South Pacific, probably within the last 2–5 million years. Dispersal of buoyant Sophora seeds to oceanic islands is the most likely explanation of its distributions. Fossil pollen dates in New Zealand are consistent with the conclusion.     

Western blot analysis of stray cat sera against Toxoplasma gondii and the diagnostic availability of monoclonal antibodies in sandwich-ELISA

A total of 198 sera from stray cats was assayed against Toxoplasma gondii antigen by western blot. Out of 198 sera assayed, 26 sera (13.1%) showed typical blot patterns against T. gondii. When spotted by ELISA absorbance and indirect latex agglutination test (ILAT) titer, all 26 cases were distributed over the cut-off value of ELISA whereas 24 cases (92.3%) were in the positive range of 1:32 or higher and 2 cases in negative range by ILAT. Among western blot negative 172 sera, 162 cases were negative in both ILAT and ELISA while 10 cases were reactive falsely such that three cases were ILAT positive with 1:32 titer and 9 cases were ELISA positive (2 cases overlapped). These 10 cases reacted peculiarly without typical binding pattern in Western blot. Sandwich-ELISA was performed with monoclonal antibodies (mAbs) of Tg563 (30 kDa, SAG1), Tg505 (22 kDa, SAG2), Tg605 (43 kDa, SAG3), Tg556 (28 kDa. GRA2), Tg737 (32 kDa, GRA6), Tg695 (66 kDa, ROP2), Tg786 (42 kDa, ROP6), and Tg621 (32 kDa, anonymous but cytosolic) clone, respectively. All western blot-positive cases were in the positive range and negative cases in the negative range clearly. Among the 10 false reactive cases, 3 cases were in the positive range with one or more mAbs. All mAbs used in this study were confirmed to be specific to T. gondii infection as a standardized sandwich-ELISA to differentiate it from other pathogens.     

The mycoflora and incidence of aflatoxin,zearalenone and sterigmatocystin in dairy feed and forage samples from Eastern India and Bangladesh

The mycoflora of a range of mixed ruminant feed and forage samples collected in Eastern India and Bangladesh were determined. Most fungi isolated from the samples were those associated with low moisture contents. Several potentially mycotoxigenic fungi and thermotolerant species were present particularly in the rice straw. The most frequently isolated fungi were: Aspergillus versicolor (Vuill.) Tiraboschi, Penicillium citrinum Thorn, Eurotium species, Wallemia sebi (Fr.) v. Arx, Aspergillus penicilloides Speg. and yeasts. Fusarium moniliforme Sheldon and Cladosporium species were prevalent in straw but not other feeds. Levels of certain individual fungi, particularly thermotolerant types, were higher in Bangladesh rice straw although overall counts were similar to those of the Indian samples. Mycotoxin analyses for aflatoxins, zearalenone and sterigmatocystin were carried out. Aflatoxins were detected in significant amounts in some feed samples from Eastern India but not in rice straw from India and Bangladesh. Zearalenone occurred in a Paspalum straw sample and three other feed samples from India and sterigmatocystin was detected in three rice straw samples from Bangladesh.     

Elevation of anα(1,3) fucosyltransferase activity correlated with apoptosis in the human colon adenocarcinoma cell line,HT-29

We studied changes in the carbohydrate expression following apoptotic cell death induced by treatment with interferon (IFN)- and anti-Fas antibody using human colon adenocarcinoma HT-29 cells. An apoptotic cell death of HT-29 accompanied with typical DNA fragmentation was observed when the cells were cultured sequentially with IFN- and anti-Fas antibody. In flow cytometric analyses, the expression of Le^x and Le^y antigen was strongly and slightly enhanced, respectively, on the cell surface in accordance with the apoptosis. When the fucosyltransferase (Fuc-T) activities of the lysates from the treated cells were examined relative to those from untreated cells, a 2.5-fold increase of (1,3)-Fuc-T activities and a slight increase of (1,2)-Fuc-T activities were observed, but little or no increase of (1,4)-Fuc-T activity was detected. In Northern blot analyses using probes for Fuc-T III, IV, V, VI and VII genes, strong RNA messages for Fuc-T III, V and/or VI and a weak RNA message for Fuc-T IV were detected in the untreated HT-29 cells. On the other hand, in the treated cells, the messages for Fuc-T III, V and/or VI were found to almost disappear and the 2.3 kb message for Fuc-T IV was observed to elevate 2.8-fold. Therefore, we suggest that the strongly increased expression of Le^x antigen found on the HT-29 cell surface might be involved in the process of apoptosis, and that the enhancement of the antigen expression seems to result from the increased activity of (1,3)-Fuc-T encoded mainly by the Fuc-T IV gene.Abbreviations Bn Benzyl - EDTA ethylenediaminetetraacetic acid (sodium salt) - SDS sodium dodecyl sulfate - D-PBS Dulbecco's phosphate buffered saline (metal free) - FITC fluorescein isothiocyanate - AIDS acquired immune deficiency syndrome - FACS fluorescence-activated cell sorter - IFN interferon - dNTP deoxynucleosides-triphosphate - PCR polymerase chain reaction - kb kilobase(s) - bp base pair(s)     

南黄海浮游甲藻的生态研究

调查南黄海浮游甲藻的种类组成、季节变化、水平分布及其与环境因素的关系,结果表明浮游甲藻类有74种,分隶于8科9属。其中高温高盐种占71．63％,广温广盐种占22．97％。低盐近岸种和冷水性种类各占2．7％。南黄海浮游甲藻细胞总量的季节分布,以夏季7月为最高峰,春季3月为最低谷,并对其生态特征和水文环境因素的关系进行了详细的研究与讨论。钩梨甲藻,赛氏鸟尾藻、圆头角藻、指状角藻和新月角藻等,仅分布于126°E以东、表层（10m）盐度34．00的海域,可作为黄海暖流的指示种。