Isolation of yeast with killer activity and its breeding with an industrial baking strain by protoplast fusion

Summary Wild strains of Saccharomyces cerevisiae were isolated from dairy products, bakery goods, fresh fruit and vegetables, and tested for killer activity. Four isolates out of 238 strains possessed killer activity. The best of these was converted to the petite form and hybridized with an industrial strain of Saccharomyces cerevisiae by protoplast fusion. Thirty-eight out of 104 isolates had killer activity, and some of these had good dough-raising activity as well.     

Visual fields of orb web and single line web spiders of the family Uloboridae (Arachnida,Araneida)

Summary In the family Uloboridae, web reduction is associated with changes in web monitoring posture and prosomal features. A spider must extend its first pair of legs directly forward to monitor the signal line of a reduced web. This posture is facilitated by shifts in prosomal musculature that cause reduced web uloborids to have a narrower anterior prosoma, a reduced or absent anterior eye row, and prominent posterior lateral eye tubercles. The eye tubercles and larger posterior eyes of these uloborids suggest that web reduction may also be accompanied by ocular changes that compensate for reduction of the anterior eyes by expanding the visual fields of the posterior eyes. A comparison of the visual fields of the eight-eyed, orb web species Octonoba octonaria and a four-eyed, reduced web Miagrammopes species was made to determine if this is true. Physical and optical measurements determined the visual angles of each species' eyes and the pattern of each species' visual surveillance. Despite loss of the anterior four eyes, the Miagrammopes species has a visual coverage similar to that of O. octonaria. This is due to (1) an increase in the visual field of each of the four remaining Miagrammopes eyes, accruing from an extension of the retina and an increase in the lens' rear radius of curvature, and (2) a ventral shift of each visual axis, associated with the development of an eye tubercle and an asymmetrical expansion of the retina. Miagrammopes monitor their simple webs from twigs or moss where they are vulnerable to predation. Therefore, maintenance of visual cover may enable them to detect predators in time to assume or maintain their characteristic, cryptic posture. It may also allow them to observe approaching prey and permit them to adjust web tension or prepare to jerk their webs when prey strikes.     

Lipid-bound sugars in malignant human breast tumors

Microsomal preparations from malignant human breast tumors catalyzed the transfer of mannose and glucose from GDP-[14C]-Man and UDP-[14C]-Glc into lipid-linked sugars and glycoprotein-like substances. As judged by several criteria the obtained lipid-linked monosaccharides behaved as dolichyl phosphate mannose and dolichyl phosphate glucose whereas lipid-linked oligosaccharides behaved as polyprenyl diphosphate derivatives. The optimum conditions for mannosyl- and glucosyl-transfer reactions and the effect of dolichyl phosphate, detergent and EDTA on incubation mixture were described.     

Chemical and physiological changes in fungi during autolysis

A comparative study was done on some of the chemical changes occurring during autolysis of cultures ofAspergillus flavus in both physiologically acid and alkaline media. The mycelium ofA. flavus lost during autolysis 44 % of its maximum dry weight in the physiologically alkaline medium, whereas this loss was apparently nil in the physiologically acid medium. Nitrogen containing compounds seemed not to be affected by autolysis either in the physiologically acid or alkaline media. The disappearance of P-containing compounds in mycelium ofA. flavus autolysed in both conditions (NO ₃ ^– and NH ₄ ⁺ as N source) amounted to 64 % in the alkaline autolysis and to nearly 77 % in the acid autolysis. The results we have obtained for the acid autolysis strongly suggest that very little activity is shown by autolytic enzymes in the interval 10–133 days of incubation, when measuring autolysis by the loss in mycelial dry weight.

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Zusammenfassung Eine vergleichende Untersuchung war unternommen an einigen der chemischen Veränderungen, die während der Autolyse der Kulturen vonAspergillus flavus in physiologischen sauren und alkalischen Medien vorkommen. Die Myzelien vonA. flavus haben während der Autolyse 44 % ihres größten Trockengewichtes in physiologisch alkalischem Medium verloren, während dieser Verlust in physiologisch saurem Medium anscheinend Null gewesen ist. Stickstoff enthaltende Substanzen erschienen während der Autolyse weder in physiologisch saueren noch in alkalischen Medien beeinflußt zu sein. Das Verschwinden von P-enthaltenden Substanzen in Myzelien vonA. flavus in Autolyse unter beiden Bedingungen (NO ₃ ^– und NH ₄ ⁺ als Stickstoffquelle) erreichte 64 % in alkalischer Autolyse und beinahe 77 % in der saueren Autolyse. Die Ergebnisse, die wir in der saueren Autolyse erhalten haben legen es sehr nahe, daß autolytische Enzyme eine sehr geringe Aktivität in der Zeitspanne von 10–133 Tagen der Inkubazion zeigen, wenn die Autolyse an dem Verlust des mycelialen Trockengewichtes gemessen wird.

     

Uptake of lysine and prolinevia separate α-neutral amino acid transport pathways inMytilus gill brush border membranes

Summary Brush border membrane vesicles (BBMV) were prepared from the gills of the marine mussel,Mytilus edulis. These membranes contained two distinct pathways for cotransport of Na⁺ and -neutral amino acids. The major pathway in mussel gill BBMV was the alanine-lysine (AK) pathway, which had a high affinity for alanine and for the cationic amino acid, lysine. The AK pathway was inhibited by nonpolar -neutral amino acids and cationic amino acids, but was not affected by -neutral amino acids or imino acids. The kinetics of lysine transport were consistent with a single saturable process, with aJ _max of 550 pmol/mg-min and aK _t of 5 m. The AK pathway did not have a strict requirement for Na⁺, and concentrative transport of lysine was seen in the presence of inwardly directed gradients of Li⁺ and K⁺, as well as Na⁺. Harmaline inhibited the transport of lysine in solutions containing either Na⁺ or K⁺. The alanine-proline (AP) pathway transported both alanine and proline in mussel gill BBMV. The AP pathway was strongly inhibited by nonpolar -neutral amino acids, proline, and -(methylamino)isobutyric acid (Me-AIB). The kinetics of proline transport were described by a single saturable process, with aJ _max of 180 pmol/mg-min andK _t of 4 m. In contrast to the AK pathway, the AP pathway appeared to have a strict requirement for Na⁺. Na⁺-activation experiments with lysine and proline revealed sigmoid kinetics, indicating that multiple Na⁺ ions are involved in the transport of these substrates. The transport of both lysine and proline was affected by membrane potential in a manner consistent with electrogenic transport.     

Sodiumd-glucose cotransport in the gill of marine mussels: Studies with intact tissue and brush-border membrane vesicles

Summary Glucose transport was studied in marine mussels of the genusMytilus. Initial observations, with intact animals and isolated gills, indicated that net uptake of glucose occurred in mussels by a carrier-mediated, Na⁺-sensitive process. Subsequent studies included use of brush-border membrane vesicles (BBMV) in order to characterize this transport in greater detail. The highest activity of Na⁺-dependent glucose transport was found in the brush-border membrane fractions used in this study, while basal-lateral membrane fractions contained the highest specific binding of ouabain. Glucose uptake into BBMV showed specificity for Na⁺, and concentrative glucose transport was observed in the presence of an inwardly directed Na⁺ gradient. There was a single saturable pathway for glucose uptake, with an apparentK _t of 3 m in BBMV and 9 m in intact gills. The kinetics of Na⁺ activation of glucose uptake were sigmoidal, with apparent Hill coefficients of 1.5 in BBMV and 1.2 in isolated gills, indicating that more than one Na⁺ may be involved in the transport of each glucose. Harmaline inhibited glucose transport in mussel BBMV with aK _i of 44 m. The uptake of glucose was electrogenic and stimulated by an inside-negative membrane potential. The substrate specificity in intact gills and BBMV resembled that of Na⁺-glucose cotransporters in other systems;d-glucose and -methyl glucopyranoside were the most effective inhibitors of Na⁺-glucose transport,d-galactose was intermediate in its inhibition, and there was little or no effect ofl-glucose,d-fructose, 2-deoxy-glucose, or 3-O-methyl glucose. Phlorizin was an effective inhibitor of Na⁺-glucose uptake, with an apparentK _i of 154nm in BBMV and 21nm in intact gills. While the qualitative characteristics of glucose transport in the mussel gill were similar to those in other epithelia, the quantitative characteristics of this process reflect adaptation to the seawater environment of this animal.     

Catabolite repression of the synthesis of inducible polygalacturonase and pectinesterase byAspergillus niger sp.

Several recent reports have described large numbers of monoclonal antibodies that cross-react with toxins A and B ofClostridium difficile; this suggests that the toxins share major epitopes. Our results show that monoclonal antibodies (MAb) against other antigens bind nonspecifically to both toxins. Therefore, we believe that the cross-reacting MAb bind by this manner and not by a true immune reaction.     

Cellulose and lignin degradation in forest soils: Response to moisture,temperature, and acidity

The concentration of lignin in plant tissue is a major factor controlling organic matter degradation rates in forest ecosystems. Microbial biomass and lignin and cellulose decomposition were measured for six weeks in forest soil microcosms in order to determine the influence of pH, moisture, and temperature on organic matter decomposition. Microbial biomass was determined by chloroform fumigation; lignin and cellulose decomposition were measured radiometrically. The experiment was designed as a Latin square with soils of pH of 4.5, 5.5, and 6.5 adjusted to 20, 40, or 60% moisture content, and incubated at temperatures of 4, 12, or 24°C. Microbial biomass and lignin and cellulose decomposition were not significantly affected by soil acidity. Microbial biomass was greater at higher soil moisture contents. Lignin and cellulose decomposition significantly increased at higher soil temperatures and moisture contents. Soil moisture was more important in affecting microbial biomass than either soil temperature or soil pH.