Effects of temperature and photoperiod on flowering in Hyptis brevipes

Few tropical species have been tested for their flowering response under controlled conditions. Hyptis brevipes Poit, is an annual herb, commonly found in wet margins of streams and ponds, being considered a weed for some perennial plantations in Brazil. Under experimental glasshouse conditions, this species proved to be an obligate short-day plant. Flowering was delayed when photoperiods longer than 8 h were given, the critical photoperiod being between 12 and 13 h. When both temperature and photoperiod were controlled, at 20°C a longer protoperiod (by almost 1 h) is still inductive compared to 25 and 30°C. The number of short-day cycles required for full induction is relatively high and dependent upon temperature; at 20°C or above, 10 cycles are adequate, but at 15°C, more short-day cycles are needed. The number of inflorescences formed as well as the floral index vary according to daylength × temperature × inductive cycle number, allowing flowering to be assessed quantitatively. Long days are inhibitory to flowering, either suppressing it completely (when symmetrically intercalated among 24 inductive cycles) or preventing the floral index from increasing.     

Molecular basis of intercellular adhesion in the biofilm-forming Staphylococcus epidermidis

The Staphylococcus epidermidis genes icaABC are involved in the synthesis of the polysaccharide intercellular adhesin (PIA), which is located mainly on the cell surface, as shown by immunofluorescence studies with PIA-specific antiserum. PIA was shown to be a linear β-1,6-linked glucosaminoglycan composed of at least 130 2-deoxy-2-amino-D-glucopyrano-syl residues of which 80–85% are N-acetylated, the rest being non-N-acetylated and positively charged. A transposon insertion in the icaABC gene cluster (ica, intercellular adhesion) led to the loss of several traits, such as the ability to form a biofilm on a polystyrene surface, cell aggregation, and PIA production. The mutant could be complemented by transformation with the IcaABC-carrying plasmid pCN27. Transfer of pCN27 into the heterologous host Staphylococcus carnosus led to the formation of large cell aggregates, the formation of a biofilm on a glass surface, and PIA expression. The nucleotide sequence of icaABC suggests that the three genes are organized in an operon and that they are co-transcribed from the mapped ica A promoter. Ica A contains four potential transmembrane helices, indicative of a membrane location. The deduced Ica A sequence shows similarity to those of polysaccharide-polymerizing enzymes, the most pronounced being with a Rhizobium meliloti N-acetylglucosaminyltransferase involved in lipo-chitin biosynthesis (22.5% overall identity and 37.4% overall similarity). This similarity suggests that Ica A has N-acetylglucosaminyltransferase activity in the formation     

Upper cretaceous rudist and stromatoporid associations of Central Oman (Arabian Peninsula)

Summary Rudist and stromatoporid associations of the Campanian from Central Oman are nearly monospecific. They are dominated byDurania aff.nicholasi, Vaccinites vesiculosus, Torreites milanovici or phaceloid and massive stromatoporids. Several other rudist genera play a secondary role. The thickness of the associations is rarely more than one metre. Solitary corals do not occur in the associations. Colonial corals are less common, although they are up to 1 m high and show considerable diversity. There are no binders. The reef structure indicates variable hydrodynamic conditions. They are always associated with very shallow water. The pureDurania aff.nicholasi patches with large colonial corals andTorreites milanovici are presumably the most rigid structures. The near monospecific associations ofVaccinites vesiculosus are widely distributed. Although mostly preserved in situ, strong currents, presumably caused by tropical storms, have repeatedly impaired and interrupted growth. The specific growth characteristics of the shell of some rudists, especially the radiolitids, enable an estimation of the individual lifespan. Frameworks of approximately 1 metre thickness probably developed in ±100 years. The sediments of the complete sections are predominantly bioclastic.     

Cloning and electrophysiological analysis of KST1, an inward rectifying K+ channel expressed in potato guard cells.

Potassium uptake by guard cells represents part of the osmotic motor which drives stomatal opening. Patch-clamp measurements have identified inward rectifying K+ channels capable of mediating K+ uptake in guard cells and various other plant cell types. Here we report the molecular cloning and characterization of a voltage-dependent K+ channel (KST1) from potato (Solanum tuberosum L.) guard cells. In situ hybridization shows expression of kst1 in guard cells. Two-electrode voltage-clamp and patch-clamp studies of the gene product after cRNA injection into Xenopus oocytes identified KST1 as a slowly activating, voltage-dependent, inward rectifying K+ channel. The single channel current voltage curve was linear in the range -160 to +20 mV, with a deduced single channel conductance of 7 pS in symmetrical 100 mM K+. This channel type, modulated by pH changes within the physiological range, required ATP for activation. In line with the properties of a K(+)-selective channel, KST1 was permeable to K+, Rb+ and NH4+ and excluded Na+ and Li+. Cs+ at submillimolar concentrations blocked the channel in a voltage-dependent manner. Related studies on potato guard cell protoplasts confirmed the biophysical characteristics of the kst1 gene product (KST1) in the heterologous expression system. Therefore, KST1 represents a major K+ uptake channel in potato guard cells.     

Degradation of 4,4'-dichlorobiphenyl, 3,3',4,4'-tetrachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl by the white rot fungus Phanerochaete chrysosporium.

The white rot fungus Phanerochaete chrysosporium has demonstrated abilities to degrade many xenobiotic chemicals. In this study, the degradation of three model polychlorinated biphenyl (PCB) congeners (4,4'-dichlorobiphenyl [DCB], 3,3',4,4'-tetrachlorobiphenyl, and 2,2',4,4',5,5'-hexachlorobiphenyl) by P. chrysosporium in liquid culture was examined. After 28 days of incubation, 14C partitioning analysis indicated extensive degradation of DCB, including 11% mineralization. In contrast, there was negligible mineralization of the tetrachloro- or hexachlorobiphenyl and little evidence for any significant metabolism. With all of the model PCBs, a large fraction of the 14C was determined to be biomass bound. Results from a time course study done with 4,4'-[14C]DCB to examine 14C partitioning dynamics indicated that the biomass-bound 14C was likely attributable to nonspecific adsorption of the PCBs to the fungal hyphae. In a subsequent isotope trapping experiment, 4-chlorobenzoic acid and 4-chlorobenzyl alcohol were identified as metabolites produced from 4,4'-[14C]DCB. To the best of our knowledge, this the first report describing intermediates formed by P. chrysosporium during PCB degradation. Results from these experiments suggested similarities between P. chrysosporium and bacterial systems in terms of effects of congener chlorination degree and pattern on PCB metabolism and intermediates characteristic of the PCB degradation process.     

Lysis of bacterioids in the vicinity of the host cell nucleus in an ineffective (fix-) root nodule of soybean (Glycine max)

In nodules of Glycine max cv. Mandarin infected with a nod ⁺fix^- mutant of Rhizobium japonicum (RH 31-Marburg), lysis of bacteroids was observed 20 d after infection, but occurred in the region around the host cell nucleus, where lytic compartments were formed. Bacteroids, and peribacteroid membranes in other parts of the host cell remained stable until senescence (40d after infection). With two other nod⁺ fix^- mutants of R. japonicum either stable bacteroids and peribacteroid membranes were observed throughout the cell (strain 61-A-165) or a rapid degeneration of bacteroids without an apparent lysis (strain USDA 24) occurred. The size distribution of RH 31-Marburg-infected nodules exhibited only two maxima compared with four in wild-type nodules and nodule leghaemoglobin content was found to be reduced to about one half that of the wild type. The RH 31-Marburg-nodule type is discussed in relation to the stability of the bacteroids and the peribacteroid membrane system in soybean.     

Distribution of sulfated mucopolysaccharides in invertebrates.

The sulfated mucopolysaccharide composition of 22 species of invertebrates belonging to the phyla Arthropoda, Mollusca, Annelida, Tunicata, Echinodermata, Coelenterata, and Porifera was analyzed. It is shown that all the species contain variable amounts of one or more types of sulfated mocopolysaccharides, most of which similar to the ones found in vertebrates. It is shown also that each species has a characteristic composition, differing from each other regarding the relative amount and type of chondroitin sulfates A, B, and C, heparitin sulfate, and heparin. The possible biological role of the sulfated mucopolysaccharides in cell recognition or aggregation or both is discussed in view of the present findings.     

Changes in sulfated mucopolysaccharide composition of mammalian tissues during growth and in cancer tissues.

The distribution of sulfated mucopolysaccharides in different tissues during growth and in cancer tissues is reported. It is shown that most of the tissues of 1 day-old rats and rabbits contain chondroitin sulfate A/C, chondroitin sulfate B and heparan sulfate in about the same proportions, whereas in adult animals chondroitin sulfate A/C decreases in concentration or disappears. Changes in the relative proportions of chondroitin sulfate B and heparan sulfate were also observed in most of the tissues. In rats, these changes occur in the first 25 days of extrauterine development. A great increase of chondroitin sulfate A/C was observed in human tumors of different origins when compared with the normal adjacent tissues. Changes in the relative proportions of chondroitin sulfate B and heparan sulfate were also observed in most of the tumors analysed. The possible role of chondroitin sulfate A/C in cell division is discussed in view of the present findings.     

Biologie des Eleonorenfalken(Falco eleonorae): 10. Der Einflu? der Horstlage auf den Bruterfolg

Zusammenfassung Der Bruterfolg des Eleonorenfalken wurde auf einer ägäischen Inselkolonie in Relation zur Horstlage untersucht. Bei Horsten mit Gratlage auf übersichtlichem Gelände war er signifikant höher (1,8 Junge/Horst) als bei den übrigen Horsten mit z. T. schlechtem Geländeüberblick (1,3 Junge/Horst). Da alle Horste gegenüber den NW-Winden geschützt lagen, waren die meisten an südlich ausgerichteten Hängen potentiell der intensiven Sonneneinstrahlung ausgesetzt. In den Horstrevieren von typisch 20 m Durchmesser gab es aber nicht immer vor Sonne geschützte Horsthöhlen, so daß bei Lufttemperaturen von 40 °C und Bodentemperaturen von bis zu 60 °C die Embryonen in den Eiern gefährdet sein können, besonders, wenn sie der direkten Sonneneinstrahlung ausgesetzt sind. Dies tritt z. B. bei einer Störung in der Brutkolonie ein. Der Bruterfolg in den sonnenexponierten Höhlen lag mit 0,8–1,3 Junge/Horst signifikant niedriger als in den sonnengeschützten Höhlen mit durchschnittlich 1,75 Junge/Horst. Neben einer normalen Infertilität von 10 % fielen weitere 8 % aller Eier in der Brutkolonie durch Sonneneinwirkung aus.

---

Biology of the Eleonora's Falcon(Falco eleonorae): 10. Breeding success in relation to nest site exposition

Summary Breeding success of the Eleonora's Falcon was studied in an Aegean island colony. In nests near cliff tops with an unobstructed view of the surroundings, a significantly higher breeding success (1.8 pulli/nest) was obtained than in other nests (1.3 pulli/nest). Since all nests were chosen protected from the wind, and as the main wind comes from NW, most nests were situated on southern slopes and are thus potentially exposed to the sun. Within a falcon territory of typically 20 m diameter in size there was not always a lime stone crevice with complete shade for the eggs. At an air temperature of 40 °C and a soil temperature of up to 60 °C, excessive sunning of an unprotected egg can be lethal for the falcon embryo. Breeding success in sun exposed nests was significantly lower (0.8–1.3 pulli/nest) than in sheltered nests (1.75 pulli/nest). In addition to a normal infertility of 10 %, about 8 % of all eggs laid were lost due to sun irradiation.