Quantification of Fungal Hyphae in Leaves of Deciduous Trees by Automated Image Analysis

An optical method to quantify the fungal hyphae within decomposing leaves of deciduous trees was developed. The plant matrix was partially destroyed under hydrolytic conditions, and fungal hyphae and cellulose residues within the leaves were stained with Calcofluor M2R. Cellulose residues were subsequently depolymerized by cellulase, and fungal hyphae were separated from the remaining plant matrix with a pressurized air-water mixture. An image analysis program to quantify the fungal hyphae was written. The program included the recognition of fungal hyphae, the elimination of stomata from the images, and the measuring of lengths of fungal hyphae. The optical method was verified by a chemical method relying on glucosamine as an indicator of fungal biomass. The fungal biomass in leaves of Fagus silvatica and Quercus petraea at early states of decomposition was 0.2 to 0.4% of the leaf weight. The biomass reached a maximum within 2 to 4 weeks (optical method, 0.5 to 0.7%; chemical method, 1 to 1.4% of the initial leaf weight) and decreased thereafter.     

Imazalil enhances the shoot-inducing effect of benzyladenine in Spathiphyllum floribundum Schott

In Spathiphyllum floribundum Petite Schott shoot induction by benzyladenine (BA) was enhanced dramatically by adding the imidazole fungicide imazalil to the medium. As the concentration of imazalil increased, the number of shoots increased, and finally their size was reduced to a small meristematic dome. An average of 127 shoots/ expiant developed when 2.5 mg/L BA was combined with 16 mg/L imazalil. Doubling the BA concentration had no significant effect on shoot induction. Imazalil did not affect the root-inhibiting effect of BA. When imazalil was applied without BA, the number of roots and total root length/plant were reduced, but no new shoots developed.Abbreviations GA gibberellic acid - BA benzyladenine - [9G]BA 9--d-glucopyranosylbenzyladenine - [9R]BA 9--d-ribofuranosylbenzyladenine.     

Mycoflora and aflatoxin production in pigeon pea stored in jute sacks and iron bins

The mycoflora, moisture content and aflatoxin contamination of pigeon pea (Cajanus cajan (L.) Millisp) stored in jute sacks and iron bins were determined at monthly intervals for a year. The predominant fungi on freshly harvested seeds wereAlternaria spp.,Botryodiplodia theobromae, Fusarium spp. andPhoma spp. These fungi gradually disappeared from stored seeds with time and by 5–6 months, most were not isolated. The fungi that succeeded the initially dominant ones were mainly members of the generaAspergillus, Penicillium andRhizopus. Population of these fungi increased up to the end of one year storage. Higher incidence of mycoflora andAspergillus flavus were recorded in jute-sack samples throughout the storage period. The moisture content of stored seeds was found to fluctuate with the prevailing weather condition, being low during the dry season and slightly high during the wet season. The stored seeds were free of aflatoxins for 3 and 5 months in jute sacks and iron bins respectively. The level of aflatoxins detected in jute-sack storage system was considerably higher than that occurring in the iron bin system. Of 196 isolates ofA. flavus screened, 48% were toxigenic in liquid culture (54% from jute sacks and 41% from iron bins).     

Cutaneous zygomycosis caused byAbsidia corymbifera in a leukemic patient

A case of cutaneous zygomycosis caused byAbsidia coryabifera in a leukemic patient submitted to chemotherapy is reported. The lesion was located on the little finger of the right hand and probably resulted from a latent osteomyelitis. It progressed to form extensive necrotic area. No systemic infection was detected and the lesion did not appear to be associated with any trauma.     

Aberrant pre-mRNA maturation is caused by LINE insertions into introns of the white gene of Drosophila melanogaster.

Insertional mutagenesis screens have provided thousands of mutant alleles for analysing genes of varied functions in Drosophila melanogaster. We here document mechanisms of insertional mutagenesis by a LINE element, the I factor, by determining the molecular structure of RNAs produced from two alleles of the white gene of D.melanogaster, wIR1 and wIR6. These alleles result from insertion of the I factor into introns of the gene. We show that sequences present within the element direct aberrant splicing and termination events. When the I factor is inserted within the white first intron it may lead to the use of a cryptic 3' splice site which does not contain the dinucleotide AG. This splicing gives rise to a chimeric messenger RNA whose synthesis is controlled differently in tissues where the mutated gene is expressed. When the I factor is inserted within the white last intron it induces synthesis of truncated mRNAs. These results provide, for the first time, mechanisms for I factor insertional mutagenesis. They are discussed in the more general context of RNA processing in Drosophila and the evolution of eukaryotic gene introns.     

Cleavage of the HIV replication primer tRNALys,3 in human cells expressing bacterial anticodon nuclease.

Anticodon nuclease is a bacterial restriction enzyme directed against tRNA(Lys). We report that anticodon nuclease also cleaves mammalian tRNA(Lys) molecules, with preference and site specificity shown towards the natural substrate. Expression of the anticodon nuclease core polypeptide PrrC in HeLa cells from a recombinant vaccinia virus elicited cleavage of intracellular tRNA(Lys),3. The data justify an inquiry into the possible application of anticodon nuclease as an inhibitor of tRNA(Lys),3-primed HIV replication. They also indicate that the anticodon region of tRNA(Lys) is a substrate recognition site and suggest that PrrC harbors the enzymatic activity.     

Oleic acid transformations by selected strains of Sphingobacterium thalpophilum and Bacillus cereus from composted manure

In a survey of 186 randomly selected microbial strains isolated from composted manure, 63 transformed oleic acid into three types of products: hydroxy fatty acid, fatty amide, and less polar oleyl lipid. Selection of oleic acid-transforming microorganisms was enhanced in nutrient agar supplemented with 0.1% (vol/vol) oleic acid at pH 7.2. Most of the 63 diverse isolates elicited inconsistent and poorly reproduced transformations. However, strains 142b (NRRL B-14797) transformed oleic acid to 10-hydroxystearic acid consistently, and strain 229b (NRRL B-14812) produced an octadecenamide. Taxonomic studies indicated that NRRL strain B-14797, possessing 1,3-dihydroxy-2-amino-15-methylhexadecane and sphinganine bases, was closely related to Sphingobacterium thalpophilum, and NRRL B-14812 was identified as Bacillus cereus.     

Tissue specific loss of proliferative capacity of parthenogenetic cells in fetal mouse chimeras

Parthenogenetic cells are lost from fetal chimeras. This may be due to decreased proliferative potential. To address this question, we have made use of combined cell lineage and cell proliferation analysis. Thus, the incorporation of bromodeoxyuridine in S-phase was determined for both parthenogenetic and normal cells in several tissues of fetal day 13 and 17 chimeras. A pronounced reduction of bromodesoxyuridine incorporation by parthenogenetic cells at both developmental stages was only observed in cartilage. In brain, skeletal muscle, heart and intestinal epithelium, this reduction was either less pronounced or observed only at one of the developmental stages analysed. No difference between parthenogenetic and normal cells was observed in epidermis and ganglia. Our results show that a loss of proliferative potential of parthenogenetic cells during fetal development contributes to their rapid elimination in some tissues. The analysis of the fate of parthenogenetic cells in skeletal muscle and cartilage development demonstrated different selection mechanisms in these tissues. In skeletal muscle, parthenogenetic cells were largely excluded from the myogenic lineage proper by early post-midgestation. In primary hyaline cartilage, parthenogenetic cells persisted into adulthood but were lost from cartilages that undergo ossification during late fetal development.     

Patterns of dispersal and seasonal migration in roe deer (Capreolus capreolus)

Roe deer ( Capreolus capreolus ) spacing behaviour, during the period between mother-fawn separation and home range establishment, was studied in southern Sweden during 1987–1992. Data were collected, using telemetry, in two non-hunted populations. Females dispersed either as yearlings, or as 2- or 3-year-olds after having migrated between non-overlapping summer and winter ranges for one and two seasons, respectively. Seasonal migration usually ended with permanent settlement in the new summer area. Males dispersed as one- or two-year-olds, or remained philopatric. Median distance moved was c. 2 km with no significant sex-bias. Both populations underwent one increase, and one stable phase. During the increase phase, the frequency of yearling dispersal was 70% in one of the populations, but dropped to 20% at high density. This drop paralleled a 14% decrease in yearling winter weights. In the other population, yearling dispersal frequency was 56% during the increase phase. This population stopped increasing at an intermediate density and dispersal frequency was kept at 75%. Weights remained high in this population. In neither of the populations, at intermediate and high densities, was a sex-bias in dispersal among yearlings evident. Dispersers were on average heavier than philopatrics. High juvenile winter weight did not predestinate yearlings to dispersal, whereas low weight seemed to prevent dispersal. On the basis of these relationships, we propose a hypothesis relating dispersal to body condition, in order to explain dispersal tendency at different population densities. Further, we suggest the reason for female migration is the advantage of residing in a group during winters when predation risk is high. Since it is difficult for females (but not for males) to join non-relatives, dispersers must go back to the natal area as long as they have too few offspring to form their own matriarchal group.     

Solid-state fermentation of carob pods byAspergillus niger for protein production: effect of particle size

Two strains ofAspergillus niger were cultured in solid-state fermentation system on carob pods ground from 1.25 to 8 mm diam. A particle size of 2.5 mm gave the highest protein content of the final product (20%, w/w) and 52% of the total soluble carbohydrates were utilized. The total tannin concentration of the carob pods decreased by 83% in 4 days of fermentation.T. Smail and O. Salhi are with the Laboratory of Microbiology, U.R.B.A.F., Institute of Biology, Tizi-Ouzou University, Algeria. J.S. Knapp is with the Department of Microbiology, The University of Leeds, Leeds LS2 9JT, UK;