Increased osmotic tolerance of some Aspergilli isolated from ‘Usar’ (alkaline) soils — A possible indication of ecological specialization

Studies on the osmotic optima for growth of some Aspergilli isolated from Indian Usar (alkaline) soils have revealed the occurrence of four osmophilic and twenty-five other species which can be categorised as facultative tolerant on the basis of their osmotic concentration optima. In addition, the Usar soil strains possess a comparatively greater osmotic tolerance than their fertile soil counterparts which may be attributed to the relatively hypertonic conditions prevailing in Usar soils.     

Primary structure of hemoglobin β-chain fromColumba livia (gray wild pigeon)

Primary structure of -chain of pigeon is presented. It was determined by amino acid sequence analysis of intact -chain and its peptides obtained by the enzymatic and chemical cleavage. Comparison of amino acid sequence of the chain with other available data shows 14 Ile, 61 Lys, and 113 Ile as residues specific to pigeon. One important replacement at ₁₁ contact is 55 MetSer.     

Foliar δ13C within a temperate deciduous forest: spatial,temporal, and species sources of variation

Summary Foliar ¹³C-abundance (¹³C) was analyzed in the dominant trees of a temperate deciduous forest in east Tennessee (Walker Branch Watershed) to investigate the variation in foliar ¹³C as a function of time (within-year and between years), space (canopy height, watershed topography and habitat) and species (deciduous and coniferous taxa). Various hypotheses were tested by analyzing (i) samples collected from the field during the growing season and (ii) foliar tissues maintained in an archived collection. The ¹³C-value for leaves from the tops of trees was 2 to 3%. more positive than for leaves sampled at lower heights in the canopy. Quercus prinus leaves sampled just prior to autumn leaf fall had significantly more negative ¹³C-values than those sampled during midsummer. On the more xeric ridges, needles of Pinus spp. had more positive ¹³C-values than leaves from deciduous species. Foliar ¹³C-values differed significantly as a function of topography. Deciduous leaves from xeric sites (ridges and slopes) had more positive ¹³C-values than those from mesic (riparian and cove) environments. On the more xeric sites, foliar ¹³C was significantly more positive in 1988 (a dry year) relative to that in 1989 (a year with above-normal precipitation). In contrast, leaf ¹³C in trees from mesic valley bottoms did not differ significantly among years with disparate precipitation. Patterns in foliar ¹³C indicated a higher ratio of net CO₂ assimilation to transpiration (A/E) for trees in more xeric versus mesic habitats, and for trees in xeric habitats during years of drought versus years of normal precipitation. However, A/E (units of mmol CO₂ fixed/mol H₂O transpired) calculated on the basis of ¹³C-values for leaves from the more xeric sites was higher in a wet year (6.6±1.2) versus a dry year (3.4±0.4). This difference was attributed to higher transpiration (and therefore lower A/E) in the year with lower relative humidity and higher average daily temperature. The calculated A/E values for the forest in 1988–89, based on ¹³C, were within ±55% of estimates made over a 17 day period at this site in 1984 using micrometeorological methods.     

Cultivation of the agarophyte Gelidium pristoides in Algoa Bay,South Africa

Biofilms were allowed to develop on wooden slides of the River Red Gum (Eucalyptus camaldulensis Dehnh., Myrtaceae) submerged in two billabongs of south-eastern Australia. The slides were placed in the photic zone and the aphotic zone, and the biofilms sampled after eight week's growth over the summer of 1989–1990 and winter of 1990. Bacterial numbers, estimated with epifluorescence microscopy, ranged from 4–78 × 10⁶ cells cm^–2. Bacteria were more abundant in the photic zone than the aphotic zone, and more abundant in summer than winter. Fewer than 0.5% of the bacteria could be cultivated on nutrient agar plates. Concentrations of phospholipids ranged from 8–79 ng cm^–2, which corresponded to bacterial abundances of 2–17 × 10⁶ cells cm^–2. Fifty five phospholipid fatty acids (PLFA) were identified, of which 16:0 (13–29% of total PFLA) was the most common. Other abundant PFLA included 16:17c (6–28%), 18:26 (3–16%), 18:33 (4–12%), 18:19c (3–5%), 18:l7c (5–11%) and 18:0 (2–8%). Minor PLFA included 14:0, i and a 15:0, 15:0, 16:l5c, 16:113c, 18:36, 18:43, 20:46 and 20:53. The PLFA profiles of the biofilms were quite different from those of the sediments and plankton. There was a clear distinction between the PLFA profiles of summer and winter biofilms, but less evidence for unequivocal site or light-regime effects.     

Studies on the capacity of the cellulase of the anaerobic rumen fungus Piromonas communis P to degrade hydrogen bond-ordered cellulose

The anaerobic rumen fungus Piromonas communis, when cultured on cotton fibre as the carbon source, produces an extracellular cellulase that is capable of solubilizing crystalline hydrogen-bond-ordered cellulose, in the form of the cotton fibre, at a rate that is greater than that of any other cellulases reported in the literature hitherto. The cell-free culture fluid is also very rich in xylan-degrading enzymes. The activity towards crystalline cellulose resides in a high-molecular-mass (approximately 700–1000 kDa) component (so-called crystalline-cellulose-solubilizing component, CCSC) that comprises endo (1 4)--D-gluconase (carboxymethylcellulase), -D-glucosidase and another enzyme that appears to be important for the breakdown of hydrogen-bond-ordered cellulose. The CCSC is associated with only a small amount of the endo-(1 4)--D-glucanase (1.9%), -D-glucosidase (0.7%) and protein (0.5%) found in the crude cell-free cellulase preparation. The CCSC, unlike the bulk of the endo-(1 4)--D-glucanase and -D-glucosidase, is very strongly absorbed on the microcrystalline cellulose, Avicel.     

Production of thermostable α-galactosidase from thermophilic fungusHumicola sp

The thermophilic fungus,Humicola sp isolated from soil, secreted extracellular -galactosidase in a medium cotaining wheat bran extract and yeast extract. Maximum enzyme production was found in a medium containing 5% wheat bran extract as a carbon source and 0.5% beef extract as a carbon and nitrogen source. Enzyme secretion was strongly inhibited by the presence of Cu²⁺, Ni²⁺ and Hg²⁺ (1mM) in the fermentation medium. Production of enzyme under stationary conditions resulted in 10-fold higher activity than under shaking conditions. The temperature range for production of the enzyme was 37° C to 55°C, with maximum activity (5.54 U ml^–1) at 45°C. Optimum pH and temperature for enzyme activity were 5.0 and 60° C respectively. One hundred per cent of the original activity was retained after heating the enzyme at 60°C for 1 h. At 5mM Hg²⁺ strongly inhibited enzyme activity. TheK _m andV _max forp-nitrophenyl--d-galactopyranoside were 60M and 33.6 mol min^–1 mg^–1, respectively, while for raffinose those values were 10.52 mM and 1.8 mol min^–1 mg^–1, respectively.     

The dynamic effects of inputs to spinal motoneurones of different type upon the outputs of γ-motoneurones mediated via recurrent inhibition

A previous dynamic model of the spinal motoneurone-Renshaw cell system has been extended by integrating -motoneurones (-MNs), which are also supposed to represent Ia inhibitory interneurones mediating reciprocal inhibition. For the recurrent inhibition of -MNs, two cases are considered: -MNs inhibiting themselves via Renshaw cells (RCs), and -MNs not subjected to self-inhibition. Two input systems are taken into account: monosynaptic Ia input distributed inhomogeneously to the three types of -MNs (S, FR, and FF), and spinally descending input from the lateral vestibular nucleus distributed inhomogeneously to the three -MN types and to -MNs. Dynamic input-output relations have been calculated in form of Bode or polar plots. The main results are: Input signals (Ia and VST) to -MNs are transmitted via RCs to -MNs with high-pass characteristics (lower cut-off around 1 Hz). The relatively high gains at high frequencies are attenuated more or less strongly by recurrent self-inhibition of -MNs depending on the overall strength of recurrent inhibition. The phase lags of -MNs with respect to the input are not frequency-independent, but vary between about-90° and-180° (at times up to-200°). To preserve in-phase activation of -and -MNs, certain criteria have to be met which are discussed in terms of additional input systems to -MNs and RCs.     

Nucleotide sequence and evolution of the orangutan ε globin gene region and surrounding Alu repeats

Summary We have mapped and sequenced the globin gene and seven surrounding Alu repeat sequences in the orangutan globin gene cluster and have compared these and other orangutan sequences to orthologously related human sequences. Noncoding flanking and intron sequences, synonymous sites of , , and globin coding regions, and Alu sequences in human and orangutan diverge by 3.2%, 2.7%, and 3.7%, respectively. These values compare to 3.6% from DNA hybridizations and 3.4% from the globin gene region. If as suggested by fossil evidence and molecular clock calculations, human and orangutan lineages diverged about 10–15 MYA, the rate of noncoding DNA evolution in the two species is 1.0–1.5×10^–9 substitutions per site per year. We found no evidence for either the addition or deletion of Alu sequences from the globin gene cluster nor is there any evidence for recent concerted evolution among the Alu sequences examined. Both phylogenetic and phenetic distance analyses suggest that Alu sequences within the and globin gene clusters arose close to the time of simian and prosimian primate divergence (about 50–60 MYA). We conclude that Alu sequences have been evolving at the rate typical of noncoding DNA for the majority of primate history.Presented at the FEBS Symposium on Genome Organization and Evolution, held in Crete, Greece, September 1–5, 1986     

Populationsanteile und H?henverbreitung einj?hriger M?nnchen beim Hausrotschwanz (Phoenicurus ochruros) im Waldviertel, Nieder?sterreich

Zuammenfassung Im niederösterreichischen Waldviertel (200–700 m üNN) stieg der relative Anteil einjähriger von 17,9 auf 50% aller revierverteidigenden Hausrotschwanz- mit zunehmender Meereshöhe. Die Zunahme betrifft vor allem einjährige dercairei-Morphe, während dieparadoxus-Morphe in geringerer Anzahl und gleichförmiger als in allen Höhenbereichen auftrat.

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The portion of first-year males in breeding populations of Black Redstarts (Phoenicurus ochruros) and their altitudinal distribution in the Waldviertel, Lower Austria

Summary In 1986, between April 13 and July 5, breeding territories of male Black Redstarts were mapped in Lower Austria (200–700 m NN), with regard to their age (first-year or older) and the plumage types of first-year (femalelike or adult malelike). Due to a greater percentage of femalelike subadult (cairei-type) in higher altitudes, the proportion of first-year was found to increase from 17,9 per cent at 200–300 m to 50 per cent above 600 m. On the contrary adultlike first-year (paradoxus-type) are evenly distributed in smaller numbers over the whole altitudinal range.

     

Sind die „Cytoplasmakugeln“ vonDelphinium X-Körper?

Zusammenfassung Die von Scharinger in den Epidermiszellen vonDelphinium cultorum Voss aufgefundenen Cytoplasmakugeln verhalten sich fluoreszenzoptisch in gleicher Weise wie die von Reiter beschriebenen X-bodies vonAichryson. Dies spricht dafür, da\ die Cytoplasmakugeln' vonDelphinium Virus-Einschlu\körper sind.     

A simple method for the isolation and characterization of thymidylate uptaking mutants in Saccharomyces cerevisiae

Summary The mutant tmp1–10 ^ts which confers thermosensitive auxotrophy for thymidylate is employed for the selection of 5-dTMP uptaking mutants. At the nonpermissive temperature yeast cells phenotypically wild type for thymidylate uptake can grow for only 3 to 4 generations in the presence of 10^–2 M 5-dTMP. Thymidylate utilizing mutants (tum mutants) were isolated which can grow in the presence of 12 to 24 g 5-dTMP/ml. Genetical analysis revealed one of these mutant strains to be a double mutant, tuml tum2. For normal growth haploid thymidylate auxotrophic strains require approximately 360 g 5-dTMP/ml when tum1 and 24 g 5-dTMP when tum2 is present, respectively. Cells prototrophic for thymidylate (TMP) harbouring tum1 tum2 will also take up 5-dTMP and incorporate it specifically into their DNA. Thymidylate utilization in such strains is independent of functional mitochondria, as similar incorporation of labelled 5-dTMP is found in isogenic strains with rho ⁺, rho ^– and rho ⁰ status. Optimal stimulation of the 5-dTMP uptaking principle in haploid TMP strains is found at 4 g 5-dTMP/ml when tum1 and tum2 are present.     

Reduced expression of a distal gene of the prn gene cluster in deletion mutants of Aspergillus nidulans: genetic evidence for a dicistronic messenger in an eukaryote.

Summary Temperature sensitive dnaAts46 mutants, in which initiation of chromosome replication is blocked at 42° C, are unable to maintain a dv plasmid at the permissive temperature unless the plasmid carries a mutation in gene P of the type permitting phage to grow in groP (dnaB) bacteria. The growth rate of dnaAts46 mutants seems to be impaired by the presence of the dvP mutant plasmid.Cold sensitive dnaAcos mutants which overinitiate replication at low temperature and grow normally only at 40° and above, can maintain efficiently dvP ⁺ plasmids as well as dvP mutants. Cold sensitivity of dnaAcos mutants is suppressed by the presence of the plasmid dvP ⁺ and by certain dvP mutants, but not by others.The gene P product seems to act by reducing the initiation potential of both types of dnaA mutants, aggravating the initiation defect in dnaAts46 and correcting the overinitiation of dnaAcos.     

Normal expression of the viral gene N interferes with growth of bacteriophage lambda in Escherichia coli 15T-.

Summary Growth of and of some lambdoid phages is considerably inhibited on strain 3057 derived from E. coli 15T^-. Mutants of which overcome this inhibition map in gene N. Some of these hty mutants are temperature sensitive for growth on E. coli K12. Thus plating of on strain 3057 allows one to isolate temperature sensitive N mutants. The hty mutants produce less than normal N activity as judged by their low efficiency of plating on a nus ^- host and by the extended latent period of some of them on normal hosts. The inability of strain 3057 to propagate can be at least partially reversed by addition of thymidine to the medium and the growth difference between hty and in 3057 increases with decreasing thymidine concentration. The amount of DNA produced by in 3057 at low thymidine concentration is lower than that produced by hty under the same conditions. Only a small percentage of the DNA produced by in 3057 is packaged into viable phage particles. This suggests that not only produces less DNA in 3057 than hty but that an important part of the DNA in 3057 is in a form which can not be packaged or which is noninfective for other reasons. A hypothesis is discussed that hty mutations enable to grow on E. coli 15T^- at low thymidine concentration because they lead to reduction in the number of single strand nicks in the DNA by reducing the intracellular endonuclease activity. Under permissive conditions conditional lethal N mutants are favored for growth on 3057 over N ⁺ which confirms the idea that N activity or the activity of a gene under N control interferes with growth in 3057 at low thymidine concentration.     

Genetic control of β-diketone and hydroxy-β-diketone synthesis in epicuticular waxes of barley

Summary Five eceriferum, (cer) mutants in barley which influence -diketone and hydroxy--diketone synthesis in spike and internode epicuticular waxes have been characterized. The mutation cer-u ⁶⁹ blocks the synthesis of hydroxy--diketones and leads to a compensatory increase in the amount of -diketones, indicating that -diketones are precursors of the hydroxy--diketones. Furthermore, highly lobed wax plates were observed for the first time on barley lemmas, in addition to the characteristic wax tubes. Both diketone classes are selectively and proportionally reduced in the spike wax of cer-i ¹⁶, which has shorter wax tubes. The three mutants cer-c ³⁶, -q ⁴², and -c,u ¹⁰⁸ synthesize neither diketone class and form no wax tubes. In contrast to the variable composition of most individual barley wax classes, only a single -diketone was identified, namely hentriacontan-14,16-dione.     

Isolation and characterization of Saccharomyces cerevisiae mutants supersensitive to G1 arrest by the mating hormone a-factor

Summary Nine independent mutants which are supersensitive (ssl ^–) to G1 arrest by the mating hormone a-factor were isolated by screening mutagenized Saccharomyces cerevisiae MAT cells on solid medium for increased growth inhibition with a-factor. These mutants carried lesions in two complementation groups, ssl1 and ssl2. Mutations at the ssl1 locus were mating type specific: MAT ssl1 ^– cells were supersensitive to -factor but MAT ssl1 ^– were not supersensitive to -factor. In contrast, mutations at the ssl2. locus conferred supersensitivity to the mating hormone of the opposite mating type on both MAT, and MATa cells. The -cell specific capacity to inactivate externally added a-factor was shown to be lacking in MAT ssl1 ^– mutants whereas MAT ssl2. cells were able to inactivate a-factor. Complementation analysis showed that ssl2 and sst2, a mutation originally isolated as conferring supersensitivity to -factor to MATa cells, are lesions in the same gene. The ssl1 gene was mapped 30.5 centi-Morgans distal to ilv5 on chromosome XII.     

Existence and uniqueness of a sharp travelling wave in degenerate non-linear diffusion Fisher-KPP equations

In this paper we use a dynamical systems approach to prove the existence of a unique critical value c ^* of the speed c for which the degenerate density-dependent diffusion equation u _ct = [D(u)u _x ] _x + g(u) has: 1. no travelling wave solutions for 0 < c < c ^*, 2. a travelling wave solution u(x, t) = (x - c ^* t) of sharp type satisfying (– ) = 1, () = 0 ^*; '(^*–) = – c ^*/D'(0), '(^*+) = 0 and 3. a continuum of travelling wave solutions of monotone decreasing front type for each c > c ^*. These fronts satisfy the boundary conditions (– ) = 1, '(– ) = (+ ) = '(+ ) = 0. We illustrate our analytical results with some numerical solutions.     

Physiological relationship between the temperate phages lambda and phi80

Summary This work deals with the ability of phage 80 to provide defective mutants of with their missing functions. Functions Involved in Recombination. As shown by others, the Int mechanism of 80 cannot excise prophage . However, 80 efficiently excises recombinants from tandem dilysogens, using its Ter mechanism. Likewise, the nonspecific mechanism Red is interchangeable between 80 and . Maturation of DNA by 80. The Ter recombinants excised by 80 from tandem dilysogens are packaged into a 80 protein coat. This contrasts with the fact, already mentionned by Dove, that 80 is extremely inefficient for packaging phage superinfecting a -lysogen. The latter result is also found when the helper phage is a hybrid with the left arm of (80hy4 or 80hy41 — see Fig. 1). However, the maturation of the superinfecting is much more efficient if the 80hy used as a helper has the att-N region of (like 80hy1). Conversely a with the att-N region of 80 (hy6 — see Fig. 1) is packaged more efficiently by 80 or 80hy4 than by 80hy1. It is suggested that the maturation of chromosome superinfecting an immune cell requires a recombination with the helper phage. Vegetative Functions. Among the replicative functoons O and P, the latter only can be supplied by 80. That N mutants are efficiently helped by 80 does not tell that 80 provides the defective with an active N product; the chromosomes are simply packaged into a 80 coat. This shows that 80 is unable to switch on the late genes of . That neither 80 nor any of the 80hy tested can provide an active N product is shown in a more direct way by their complete failure to help N ^-r₁₄; this phage carries a polar mutation which makes the expression of genes O and P entirely N-dependant. The maturation of a N ^- by 80 contrasts with the fact that mutants affected in late genes (A, F or H) are not efficiently helped by 80. This suggests that the products coded by these genes are not interchangeable between 80 and , and that packaging of DNA into 80 coats is possible but inhibited when late proteins are present in the cell. Activation of the Late Genes. Among the im ₈₀ h ⁺ hybrids tested, only 80hy41 is able to switch on the late genes of a N defective mutant. This hybrid differs from the other hybrids studied here, by the fact that it has the Q-S-R region of (see Fig. 1). The results are consistant with the view that the product of Q gene is sufficient for activating the late genes of a DNA. N would thus control the expression of late genes only indirectly by controlling the expression of gene Q (Couturier & Dambly have independantly reached the same conclusion, 1970). Furthermore the failure of 80 and of the 80hy1 and 80hy4 to activate the late genes of would imply that these phages are unable to provide an Q product active on the chromosome Reciprocally, switches on the late genes of prophage 80hy41, but not of prophages 80hy1 and 80hy4. This suggests that the initiation of late genes expression takes place at a main specific site located in the Q-S-R region of the chromosome. The expression of the late genes would thus be sequential, and proceed through the left arm only when steaky ends cohere. Similar conclusions were reached independantly by Toussaint (1969) and by Herskowitz and Signer (1970).

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Ce travail a été réalisé dans le cadre du contrat d'association Euratom-U. L. B. 007-61-10 ABIB et avec l'aide du Fonds de la Recherche Fondamentale Collective.     

Changes in Resistance to Salinity and Temperature in Some Species of Polychaetes from the White Sea in Early Ontogenesis

We studied the effects of different salinities on plankton larvae of some polychaetes in the White Sea. It has been found that the salinity resistance of Alitta virens (Nereidae) increases during ontogenesis. Successful fertilization and further larval development in this species occur at the salinity of 22 to 34; embryos taken into the experiment at the stage of 32 blastomeres, trochophores, and early nektochaetes could survive and normally develop at the salinity of 16–32, 14–45, and 12–45 respectively. The rate of settling and metamorphosis in late nektochaetes of A. virens at normal or lowered (down to 14) salinity is dependent on temperature in the range of 5 to 23°C. It is found that the larvae of Harmothoe imbricata (Polynoidae) show the greatest salinity resistance at the stage of nektochaeta, whose lower limit of salinity is 14. Later larval stages of these species can survive in a wide range of salinity due to the development of a provisory nephridial system. The eurybionty of larvae of Spirorbis spirorbis ready for metamorphosis was higher than that in the larvae of Circeus spirillum (Spirorbidae). Under salinity reduced down to 10 the larvae of S. spirorbis die in 8–14 days, whereas more stenohaline larvae of C. spirillum die by the 3-rd day of the experiment. At water temperatures under 5°C the survival of S. spirorbis was the highest at three examined values of salinity, whereas C. spirillum showed the highest survival only under normal salinity.