Coprophilous fungi of the horse

A total of 1267 microfungi, including 35 Myxomycetes, were recorded from the fecal samples of the 60 horses; of these 395 were found on 20 saddle-horse feces, 363 on 20 race-horses and 509 on 20 working-horses. Eighty two species representing 53 genera were recorded; of these 7 were Zygomycetes, 18 Ascomycetes, 1 Basidiomycetes and 25 Fungi Imperfecti: 2 Myxomycetes. Common coprophilous fungi are in decreasing orderPilobolus kleinii, Saccobolus depauperatus, Mucor hiemalis, Lasiobolus ciliatus, Podospora curvula, Petriella guttulata, M. circinelloides, Coprinus radiatus, Dictyostelium mucoroides, Sordaria fimicola, C. miser, C. stercorarius, Acremonium sp., Coprotus granuliformis, Graphium putredinis, Iodophanus carneus, Chaetomium murorum, Podospora communis, P. inaequalis, P. setosa, Saccobolus versicolor andCladosporium cucumerinum. Species ofMyrothecium verrucaria, Actinomucor elegans, Kernia nitida, Spiculostilbella dendritica andMucorparvispora were found exclusively in working-horses feces.Badhamia sp., Anixiopsis stercoraria, Echinobotryum state ofD. stemonitis, Geotrichum candidum andOidiodendron sp. were found only in saddle-horses feces.Chlamidomyces palmarum andPhilocopra sp. were found exclusively in race-horses feces.Notes on infrequent or interesting fungi includeThamnostylum piriforme, Phialocephala dimorphospora, Rhopalomyces elegans andSpiculostilbella dendritica.     

Myo-inositol dehydrogenase(s) from Acetomonas oxydans

Summary Experimental studies have been undertaken with a view to isolation of the enzyme(s) responsible for the stereospecific oxidation of myo-inositol. A partial fractionation has been achieved and the properties of this extract examined. Results show that the active enzyme may well have a cytochrome component and there is indication that the stereospecificity ofAcetomonas oxydans results from permease as opposed to dehydrogenase activity. Kinetic experiments suggest that only one type of active enzyme site is involved in the dehydrogenation of myo-inositol.Departments of Chemistry and Applied Biology     

Nucleotide sequences of HS-α satellite DNA from kangaroo rat dipodomys ordii and characterization of similar sequences in other rodents

The most common repeated nucleotide sequences of the highly repetitive satellite HS-α fraction from kangaroo rat Dipodomys ordii was determined using ribosubstitution methods. This sequence was α nucleotides long and represented about 25% of the total HS-α satellite DNA, while the remaining DNA was composed of sequence variants related to the most common sequence. The sequences of the commonest of these variants are reported. Furthermore, the most common repeated sequence was identical to that reported for the α satellite of guinea pig Cavia porcellus. The α satellites of guinea pig, Cavia porcellus, pocket gopher, Thomomys bottae and antelope ground squirrel, Ammospermophilus leucurus, are shown to have sequences in common with the kangaroo rat. This implies that the simplest repeated sequences of mammalian satellite DNAs may persist over much longer evolutionary times than previously thought.Attempts to explain the very rapid quantitative changes in satellites whose sequence is strongly conserved have led us to consider that they might have a role in sympatric speciation. Among the novel features of the model presented is that fluctuations in satellites could be due to “speciation genes.” Such genes would confer a strong selective advantage in certain situations, and could explain the many puzzling instances in which large numbers of new related species have appeared over a short evolutionary span.     

Properties of a major α-globulin of rice endosperm

Globulin was isolated from milled rice (Oryza sativa, line IR480-5-9) by 5% NACl extraction and was precipitated by (NH₄)₂SO₂ or by dialysis against water. The extract was purified by repeated isoelectric precipitation at pH 4.5. The major globulin fraction (40%) exhibited one band by electrophoresis at pH 4.5 but two bands at pH 8.3. Similarly, one sharp peak was shown by sedimentation corresponding to 1.41S (α-globulin) in acetic acid (pH 2) and NaOH (pH 11.7) but a broad asymmetric peak was obtained at pH 6.7, 8.3 and 8.9. Gel filtration of the α-globulin at pH 6.5 exhibited 2 proteins with MW 20 000 and 98 000. The results suggest a pH dependent aggregation phenomenon. The two proteins could not be separated by DEAE-cellulose chromatography. SDS-polyacrylamide electrophoresis of α-globulin revealed one subunit with MW 18 000. This α-globulin is poorer in lysine and histidine but richer in cystine, methionine, arginine, tyrosine and glutamic acid than whole milled rice proteinfa]Taken part from the M.S. thesis of AAP from the University of the Philippine at Los Baños (1977).     

Protein-lipid interactions and differential scanning calorimetric studies of bacteriorhodopsin reconstituted lipid-water systems

Bacteriorhodopsin has been reconstituted at various molar concentrations into liposomes of dimyristoyl- and also of dipalmitoylphosphatidylcholine. Differential scanning calorimetry indicates that as the protein concentration within the lipid bilayer increases, the cooperativity of the lipid phase transition is reduced, i.e. the transition is broadened, while the midpoint transition temperature remains virtually unchanged. Freeze-fracture electron microscopy of our preparation shows, in agreement with previous data from other laboratories, that extensive protein aggregation occurs when the liposome is cooled below the T_c transition temperature of the lipid. Laser flash photolysis measurements of protein rotation of the bacteriorhodopsin show, especially in the case of protein-rich recombinants, that protein aggregates exist even above T_c. The perturbation caused by the presence of bacteriorhodopsin in the lipid bilayer is similar to that produced by other intrinsic proteins. The difficulty of correlating the observed calorimetric enthalpy data with a simple concept of a ‘boundary lipid layer’ based upon consideration of a single isolated protein is discussed in view of the occurrence of protein aggregates both above and below T_c. It is concluded that the reduction of enthalpy is related to the number of lipids which solvate the protein aggregates within the protein-lipid patches and are thereby removed from the cooperative melting and enthalpy of the remaining regions of pure lipid.     

Fructose 1,6-bisphosphatase: Dissociation of AMP cooperativity and AMP inhibition by carbamylation

Selective treatment of pig kidney fructose 1,6-bisphosphatase with potassium cyanate leads to the formation of an active carbamylated enzyme that has lost the cooperative interactions among AMP sites, but retains sensitivity to inhibition of catalytic activity by the regulator AMP. Incorporation data on [¹⁴C]KNCO indicate that the loss of enzyme cooperativity at the AMP sites is related to selective carbamylation of four lysine residues per mole of tetrameric enzyme. Exhaustive carbamylation suggests that a second lysine residue per subunit is essential for AMP inhibition.     

Progressive changes in the structure and dynamics of the phytoplankton community along a pollution gradient in a lowland river — a multivariate approach

The phytoplankton of the River Lujan (Buenos Aires, Argentina) was studied for a period of 18 months, together with physical and chemical variables, in relation to a pollution gradient. 167 taxa were recorded within a seasonal succession characterized by dominance of diatoms with a brief summer green algae facies. A combination of several biotic indices and multivariate analysis was employed to assess the impact of pollution on the phytoplankton community. The biotic indices used were species diversity and richness, algal quotients (green algae/diatom ratio, Centrales/Pennales ratio) and the SD succession rate index. Multivariate procedures included cluster analysis and ordination by PCA of both species and samples, stepwise discriminant analysis and multiple discriminant analysis of variance (MANOVA). Results indicate that community dynamism is attenuated at the more polluted sites, concomitant with an increased predominance of a broad-tolerance algal assemblage, co-dominated by Cyclotella meneghiniana and Nitzschia stagnorum. The changes in the community structure and dynamics described herein involved alterations in the distribution and relative proportions of the algae, rather than modifications in the basic species composition. These changes may not be readily detectable by methods which over-simplify the ecological information, such as systems of indicator species and biotic indices, designed to assess the degree of pollution. The suitability of multivariate analysis and biotic indices in river phytoplankton studies is further discussed.     

Effect of drying period and soil moisture on egg hatch of the tadpole shrimp (Notostraca: Triopsidae).

Tadpole shrimp (Triops spp.) are potential biological control agents against larval mosquitoes in temporary ponds and flood-irrigated fields. In some rice field situations, however, they may become pests that uproot and eat young rice plants. In cursory observations, it has been reported that tadpole shrimp eggs do not readily hatch on flooding when the soil or substrate containing eggs is moist before flooding. The relationship between drying (moisture content) of soil and tadpole shrimp hatch was determined in studies conducted in mesocosms at the University of California Aquatic and Vector Control Research facilities at Riverside and at Oasis in the Coachella Valley of southern California. In laboratory hatching trials, an increase in hatch of Triops longicaudatus (LeConte) with declining soil moisture content was demonstrated (t = 8.4, P less than 0.001; r2 = 0.76). In field trials in mesocosms at Riverside, egg hatch increased with increased drying period and declining soil moisture content (G = 29.8, P less than 0.01). No hatch of eggs occurred after 3 d of drying, when soil moisture content was high, but a high level of hatching occurred after 7 and 14 d of drying, when soil moisture declined to low levels. At Oasis, soil moisture did not decrease with drying time because of porous soil and capillary action of water from adjacent flooded mesocosms and thick vegetation covering the pond bottoms. Therefore, hatch rates at Oasis were not associated with the length of the drying period (G = 35, P greater than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Kinetics of leaf nitrite reductase with Methyl Viologen and ferredoxin under controlled redox conditions.

The dexamethasone binding capacity of embryonal carcinoma cells and their differentiated derivatives was investigated. Manipulation of the embryonal carcinoma cell-culture conditions resulted in an unstable reversible expression of the glucocorticoid receptors. Stable expression of the receptors is observed when these cells are induced to differentiate. Cells grown under identical conditions were assayed for their ability to bind epidermal growth factor.