Antagonism between growth and flocculation inPichia stipitis NRRL Y-7124:Influence of Ca +2 and Mg +2 ions

Summary The effects of Mg⁺² and Ca⁺² ion concentrations onPichia stipitis growth and flocculation were studied by a 2×2 factorial design. Negative interaction was detected between these ions (p<0.01): maximum growth rate was attained with high Mg⁺² (3 mM) and low Ca⁺² (0.34 mM) concentration levels, whereas the inverse ionic ratio was required to reach the maximum flocculation extent. Neither stimulatory or inhibitory effects on growth or flocculation were observed by increasing other cations (Zn⁺², Mn⁺², Co⁺², Fe⁺²) or vitamins concentration. An antagonistic relationship between growth and flocculation was concluded.     

A field manipulation of spatial relations among male mantled howler monkeys

To test the hypothesis that dominance rank is reflected in spatial relationships and rates of vocalization, a field manipulation was performed removing the third-ranked male from a three-male group of mantled howler monkeys, significantly decreasing the interindividual distance (IID) between the first- and second-ranked males and increasing the rates of vocalization (VR) between them. After five days, the third-ranked male returned to his group, and IID's and VR's returned to premanipulation levels. During the manipulation phase, the second-ranked male was able to achieve closer proximity to females than during the premanipulation or postmanipulation periods, suggesting that he found it less difficult to control relations with the first-ranked male when the third-ranked male was absent. All statistically significant results were a function of behavioral changes by the second-ranked male. The study's findings may reflect the importance of male coalitions in the regulation of male-male competition and the relationship between spatial and acoustic variables and sexual selection.     

Optimisation of batch culture conditions for cyclodextrin glucanotransferase production from Bacillus circulans DF 9R

Background  

The extracellular enzyme cyclodextrin glucanotransferase (CGTase) synthesizes cyclic malto-oligosaccharides called cyclodextrins (CDs) from starch and related α-1,4-glucans. CGTases are produced by a variety of bacteria, mainly Bacillus species, by submerged culture in complex medium. CGTases differ in the amount and types of CDs produced. In addition, CGTase production is highly dependent on the strain, medium composition and culture conditions. Therefore we undertook this study with a newly isolated strain of Bacillus circulans.     

Substantia nigra dopaminergic neurons and striatal interneurons are engaged in three parallel but interdependent postnatal neurotrophic circuits

The striatum integrates motor behavior using a well‐defined microcircuit whose individual components are independently affected in several neurological diseases. The glial cell line‐derived neurotrophic factor (GDNF), synthesized by striatal interneurons, and Sonic hedgehog (Shh), produced by the dopaminergic neurons of the substantia nigra (DA SNpc), are both involved in the nigrostriatal maintenance but the reciprocal neurotrophic relationships among these neurons are only partially understood. To define the postnatal neurotrophic connections among fast‐spiking GABAergic interneurons (FS), cholinergic interneurons (ACh), and DA SNpc, we used a genetically induced mouse model of postnatal DA SNpc neurodegeneration and separately eliminated Smoothened (Smo), the obligatory transducer of Shh signaling, in striatal interneurons. We show that FS postnatal survival relies on DA SNpc and is independent of Shh signaling. On the contrary, Shh signaling but not dopaminergic striatal innervation is required to maintain ACh in the postnatal striatum. ACh are required for DA SNpc survival in a GDNF‐independent manner. These data demonstrate the existence of three parallel but interdependent neurotrophic relationships between SN and striatal interneurons, partially defined by Shh and GDNF. The definition of these new neurotrophic interactions opens the search for new molecules involved in the striatal modulatory circuit maintenance with potential therapeutic value.     

Role of Ryanodine Receptors in the Assembly of Calcium Release Units in Skeletal Muscle

Abstract. In muscle cells, excitation–contraction (e–c) coupling is mediated by “calcium release units,” junctions between the sarcoplasmic reticulum (SR) and exterior membranes. Two proteins, which face each other, are known to functionally interact in those structures: the ryanodine receptors (RyRs), or SR calcium release channels, and the dihydropyridine receptors (DHPRs), or L-type calcium channels of exterior membranes. In skeletal muscle, DHPRs form tetrads, groups of four receptors, and tetrads are organized in arrays that face arrays of feet (or RyRs). Triadin is a protein of the SR located at the SR–exterior membrane junctions, whose role is not known. We have structurally characterized calcium release units in a skeletal muscle cell line (1B5) lacking Ry₁R. Using immunohistochemistry and freeze-fracture electron microscopy, we find that DHPR and triadin are clustered in foci in differentiating 1B5 cells. Thin section electron microscopy reveals numerous SR–exterior membrane junctions lacking foot structures (dyspedic). These results suggest that components other than Ry₁Rs are responsible for targeting DHPRs and triadin to junctional regions. However, DHPRs in 1B5 cells are not grouped into tetrads as in normal skeletal muscle cells suggesting that anchoring to Ry₁Rs is necessary for positioning DHPRs into ordered arrays of tetrads. This hypothesis is confirmed by finding a “restoration of tetrads” in junctional domains of surface membranes after transfection of 1B5 cells with cDNA encoding for Ry₁R.     

Survival and behavioral characteristics of amphidromous goby larvae of Sicyopterus japonicus (Tanaka, 1909) during their downstream migration

To understand the ecology and environmental tolerances of newly hatched larvae of the amphidromous fish Sicyopterus japonicus during their downstream migration, the salinity tolerance of eggs, 0-15 day old larvae, and adults, and the temperature tolerance, specific gravity and phototaxis of hatched larvae were examined. Tolerances of adults were measured as survival after a 24 h challenge in freshwater (FW), brackish water (1/3 SW) and seawater (SW). The survival rate of adult S. japonicus was 100% in FW and 1/3 SW, while none survived in SW. Hatching success of eggs (30 eggs each) was significantly higher in FW (mean: 73%) and 1/3 SW (73%) than in SW (19%). Tolerance of newly hatched larvae to salinity and temperature was investigated in different combinations of salinities (FW, 1/3 SW and SW) and temperatures (18, 23 and 28 °C). Larval survival was significantly different in each salinity and temperature. Survival rate was significantly higher in 1/3 SW than in FW and higher in SW than in FW at 23 °C and 28 °C. At the latter part of the experiment, there was no survival in FW and at 28 °C. Survival was higher in lower temperatures, but larval development did not occur in FW. Specific gravity of newly hatched larvae was 1.036 at 28 °C and 1.034 at 23 °C. When exposed to a light source on one side of an aquarium, larval distribution was not affected. Our results indicated larval S. japonicus are more adapted to brackish water and seawater than freshwater, while the adults and eggs are more adapted to freshwater and brackish water than seawater. This is consistent with their amphidromous life history with growth and spawning occurring in freshwater and the larval stage utilizing marine habitats.