79 research outputs found
Both recombinant African catfish LH and FSH are able to activate the African catfish FSH receptor
LH and FSH are heterodimeric glycoprotein hormones, composed of a common alpha-subunit non-covalently associated with a hormone-specific beta-subunit. Repeated efforts to isolate catfish FSH (cfFSH) have not been successful and only catfish LH (cfLH) has been purified from catfish pituitaries. Recently, however, we succeeded in cloning the cDNA encoding the putative cfFSHbeta; the cDNAs for the alpha- and beta-subunit of cfLH have been cloned before. Here we report the expression of biologically active cfLH and cfFSH in the soil amoeba, Dictyostelium discoideum. The biological activity of the recombinant hormones was analyzed using cell lines transiently expressing either the cfLH receptor or the cfFSH receptor. Moreover, a primary testis tissue culture system served to study the steroidogenic potency of the recombinant hormones. Our results demonstrated that Dictyostelium produced biologically active, recombinant catfish gonadotropins, with recombinant cfLH being almost indistinguishable from its native counterpart, purified from pituitaries. Although recombinant cfFSH has significant effects in the bioassays used in this study, the specific function of native cfFSH in the control of reproduction and its expression patterns are not yet understood
The Falkland Islandsâ palaeoecological response to millennialâscale climate perturbations during the PleistoceneâHolocene transition: implications for future vegetation stability in the southern ocean islands
Oceanic island flora is vulnerable to future climate warming, which is likely to promote changes in vegetation composition, and invasion of nonânative species. SubâAntarctic islands are predicted to experience rapid warming during the next century; therefore, establishing trajectories of change in vegetation communities is essential for developing conservation strategies to preserve biological diversity. We present a Lateâglacialâearly Holocene (16 500â6450âcal a bp) palaeoecological record from Hooker's Point, Falkland Islands (Islas Malvinas), South Atlantic. This period spans the PleistoceneâHolocene transition, providing insight into biological responses to abrupt climate change. Pollen and plant macrofossil records appear insensitive to climatic cooling during the Lateâglacial, but undergo rapid turnover in response to regional warming. The absence of trees throughout the Lateâglacialâearly Holocene enables the recognition of farâtravelled pollen from southern South America. The first occurrence of Nothofagus (southern beech) may reflect changes in the strength and/or position of the Southern Westerly Wind Belt during the Lateâglacial period. Peat inception and accumulation at Hooker's Point is likely to be promoted by the recalcitrant litter of windâadapted flora. This recalcitrant litter helps to explain widespread peatland development in a comparatively dry environment, and suggests that windâadapted peatlands can remain carbon sinks even under low precipitation regimes
The weather in some beds in the Netherlands and its possible consequences for development of allergenic mites and fungi
Pollen- und Hausstaub-Allergene
Allergische Krankheiten oder Allergosen sind Storungen des normalen Ablaufes von Körperfunktionen, die durch die Bildung von Antikörpern in einem sensibilisierten Organismus verursacht werden. Allergie bedeudet wörtlich: ein verandertes Reaktionsvermögen. In der Ă€rztlichen Praxis bedeudet es, daĂ ein bestimmtes Individuum, der Patient, verglichen mit vielen anderen, abnormal reagiert. Dabei werden vor allem ubermaĂig starke Reaktionen gemeint, so daĂ im allgemeinen Sprachgebrauch Allergie mehr oder weniger synonym ist mit Ăberempfindlichkeit
Wall-bound proteins of pollen tubes after self- and cross-pollination in Lilium longiflorum
Self-incompatibility alleles control a low molecular weight, basic protein in pistils of Petunia hybrida
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PULSATORY GROWTH OF POLLEN TUBES - INVESTIGATION OF A POSSIBLE RELATIONSHIP WITH THE PERIODIC DISTRIBUTION OF CELL-WALL COMPONENTS
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