A polymorphic repetitive-sequence PR1 family evidence for meiotic instability

When EcoRI digests of mouse genomic DNA were subjected to Southern blot analysis with the polymorphic repetitive sequence PR1 as a probe, one satellite-like band of 3.5 × 10³ base-pairs, designated as PR1 family B, was detected in BALB/c-strain mice, but not in the DDD/1- or MOA-strain mice. Analysis of recombinant phage clones revealed that the repeating unit of the PR1 family B was 13.5 × 10³ base-pairs long. This family consisted of a tandem array of repeating units and occupied as much as 2% of one BALB/c chromosome. Since the BALB/c-specific PR1 family B is not present in DDD/1 or MOA mice, the unpaired portion of the BALB/c chromosome may be looped out in a synaptonemal complex during meiosis in F₁ hybrids of the BALB/c strain with DDD/1 or MOA. To determine the fate of this extra DNA, we examined the genotypes of the F₁ hybrid mice and of the segregating populations. Although the PR1 patterns of F₁ and most N₂ mice are consistent with typical Mendelian inheritance, some N₂ progeny showed an abnormal 3.5 × 10³ base-pair band of unexpectedly reduced intensity. This indicated that the extra DNA of PR1 family B occasionally underwent recombination during meiosis in F₁ mice, resulting in its apparent excision. Examination of PstI digests supported this interpretation.     

Soybean alcohol dehydrogenase

Alcohol dehydrogenase was prepared from germinating soybean seeds. Specific activity was increased from 511 to 31316 units. The coenzyme is NAD with a K_m of 10^?4M. Allyl alcohol is oxidized faster than ethanol; with the latter substrate, the K_m is 1.3 × 10^?2M, and the pH optimum 8.7. The enzyme catalyses acetaldehyde reduction, with a K_m of 10^?2M and a pH opt of 7.1. The MW is 53(±5) × 10^?3.     

Some characteristics of a new isolate of Helicosporidium and its effect upon mosquitoes

A Helicosporidium sp. was isolated by feeding spores concentrated by continuous flow centrifugation from ditch water to starved Heliothis zea larvae. This Helicosporidium sp was infectious to Anopheles quadrimaculatus, Culex salinarius, and Aedes aegypti with IC₅₀'s of 4.4 × 10², 2.6 × 10⁴, and 2.4 × 10⁴ spores/ml, respectively. Larval mortality was dosage dependent with LC₅₀ values 72 hr postexposure of 6.8 × 10⁴ for An. quadrimaculatus, 9.4 × 10³ for Cx. salinarius, and 1.5 × 10⁵ for Ae. aegypti. The spores of this Helicosporidium were also tolerant of freezing and desiccation. Because of these traits and the melanization response they provoked in host tissues, this is probably not naturally a mosquito pathogen and is most likely from a terrestrial insect.     

N+ ion beam implantation of tannase-producing Aspergillus niger and optimization of its process parameters under submerged fermentation

Low-energy ion implantation as a novel mutagen has been increasingly applied in the microbial mutagenesis for its higher mutation frequency and wider mutation spectra. In this work, N⁺ ion beam implantation was used to enhance Aspergillus niger TA9701 in tannase yield. The optimization of process parameters under submerged fermentation was carried out to further improve the tannase yield of the mutant, Aspergillus niger J-T18. The results indicate that an excellent mutant J-T18 with a yield of 38.5 IU/mL, that is five times that of the original strain, was achieved by nine successive implantations under the conditions of 10 keV and 30–40 (×2.6?×?10¹³) ions/cm². This optimization further increased the yield of the mutant by 42 %, i.e. 53.6 U/mL which occurred in the mutant cultivated in the optimal fermentation culture medium composed of: rice flour 5 %; ammonium sulfate 1 %; tannic acid 2 %; calcium carbonate 0.5 %; manganese sulfate 0.1 %; and dipotassium phosphate 0.3 %; incubated at 30°C and 180 rpm for 72 h.     

Changeability of sperm chromatin structure during liquid storage of ovine semen in milk-egg yolk- and soybean lecithin-based extenders and their relationships to field-fertility

The aim of this experiment was to study the effect of semen extender on sperm chromatin structure and to correlate chromatin integrity with field-fertility of preserved ram semen. Ejaculates of at least 2 × 10⁹ sperm/ml and 70 % progressive motility were collected using an artificial vagina from Chios rams (n = 11, 4–6 years old), split-diluted to 1 × 10⁹ sperm/ml with milk-egg yolk- and soybean lecithin (Ovixcell^®)-based extenders, packaged in 0.5-ml straws and examined after 6, 24 and 48 h of storage at 5 ± 1 °C. Evaluation endpoints were computer-assisted sperm motion analysis, fluorescence-based analysis of chromatin structure by chromomycin A₃ and acridine orange assays, and 65-day pregnancy rate (PR) of 34- to 36-h preserved semen after intra-cervical insemination of ewes (n = 154) in progestagen-synchronized estrus. Neither extender nor storage time had any influence on incidence of decondensed chromatin. Unlike Ovixcell^® extender, deterioration of sperm motility (P < 0.01) and chromatin stability (P < 0.005) was detected after 48 h of storage in milk-egg yolk extender. Sperm motility accounted for 14.4–18.5 % of variations in chromatin integrity (P < 0.001). No significant difference was found in PR of Ovixcell^®- and milk-egg yolk-stored semen. Nevertheless, PR differed between rams (14.3–71.4 %; P < 0.025). Chromatin integrity explained 10.2–56.3 % of variations in PR (P < 0.05–0.01). A pronounced decline in PR (19.1 %) was observed when percentages of decondensed and destabilized chromatin have reached thresholds of 10.5–30 % and 4–9 %, respectively. In conclusion, Ovixcell^® is superior to milk-egg yolk extender in preserving chromatin stability and motility. Chromatin defects are negatively associated with sperm fertility.     

Quantitative studies on the pathogenicity of Nosema carpocapsae,a microsporidian pathogen of the codling moth,Cydia pomonella,in New Zealand

The pathogenicity of Nosema carpocapsae for codling moth was studied using dose-infectivity experiments. The IC₅₀ (median infective concentration) was similar for the five larval instars (range 4.0 × 10³ to 6.7 × 10⁴ spores/ml). Spore loads in moths ranged from 6.0 × 10⁶ to 7.1 × 10⁷ spores per moth and varied with dose and with larval age at infection. The infection does not cause mortality but does reduce the fecundity and fertility of infected moths. Nosema carpocapsae is transmitted transovarially as well as horizontally. Infected eggs were not produced by healthy females mated with infected males, although such pairs generally produced fewer eggs than healthy pairs.     

Soybeans and radish leaves contain only one of the sulfonium diastereoisomers of S-adenosylmethionine

Using a liquid chromatography method that separates the two sulfonium diastereoisomers of adenosylmethionine, we have found that immature soybeans, soybean callus culture, radish leaves, yeast and rat liver contain only the (S)-sulfonium form of S-adenosylmethionine. Our findings contradict the suggestion by Stolowitz and Minch that 10–20% of naturally-occurring adenosylmethionine may have the (R)-configuration at the sulfonium pole. Absence of the (R)-sulfonium isomer of adenosylmethionine in biological materials indicates that the (R)-sulfonium form of adenosylmethionine present in commercial adenosylmethionine samples is an artifact of the isolation procedure. Our method of measuring the isomers of adenosylmethionine enabled us to readily determine the rate of racemization and hydrolysis of adenosylmethionine. Our rate constants for racemization (K_r) and hydrolysis (K_h) were 2.4 × 10^?6 sec^?1 and 12.3 × 10-^?6 sec^?1, respectively; values which are noticeably different from those of Wu and co-workers which were obtained with a more complicated method (K_r = 8 × 10^?1 sec^?1; K_h = 6 × 10^?6 sec^?1). We believe the absence of the (R)-isomer in vivo is best explained by stabilization of the (S)-isomer as suggested by Wu et al. Although the tissues we have analysed contained the (S)-sulfonium form of adenosylmethionine exclusively, when ethionine-resistant soybean cell lines were given ethionine, they accumulated both sulfonium diastereoisomers of adenosylethionine.     

Bioassay of a nucleopolyhedrosis virus of the gypsy moth, Porthetria dispar

The pathogenicity of an American isolate of the nucleopolyhedrosis virus of Porthetria dispar was studied. Laboratory data on third-instar larvae showed that mortality was directly related to virus concentration. The computed LD₅₀ was 1,729 PIBs/larva or 72 PIBs/mg larval body weight. The LT₅₀'s for 2.5 × 10⁶, 2.5 × 10⁵, 2.5 × 10⁴, 5 × 10³, and 2.5 × 10³ PIBs/larva were 8.1, 9.9, 11.3, 12.2, and 13.1 days, respectively. Approximately 37 and 60% of the total larval mortality occurred during the third- and fourth-instar, respectively. The periods to pupation and the pupal weights of survivors apparently were not affected by virus concentration. Moth emergence from surviving pupae was not reduced.     

Characterization of the <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> Isolates Virulent Against Rice Leaf Folder, <Emphasis Type="Italic">Cnaphalocrocis medinalis</Emphasis> (Guenee)

Soil samples were collected from different rice fields of Singur, Hooghly, West Bengal, India. Spore forming bacteria were isolated from the soil samples and among them, two isolates (BUSNC25 and BUSNC26) were larvicidal against third, fourth and fifth instar larvae of rice leaf folder, Cnaphalocrocis medinalis. The phenotypic, biochemical characterization and 16S rDNA analysis of the two isolates were done. On the basis of phenotypic, biochemical and phylogenetic analysis, the selected bacterial isolates (BUSNC25 and BUSNC26) were identified as Bacillus thuringiensis. The antibiotic sensitivity tests of these two isolates against selected doses of some standard antibiotics were done. Against the 3rd, 4th and 5th instar larvae of C. medinalis, the LC₅₀ values of BUSNC25 were 2.45 × 10⁴, 1.325 × 10⁴ and 2.35 × 10⁴ cfu/ml and of BUSNC26 were 3.375 × 10⁴, 1.9 × 10⁴ and 3.325 × 10⁴ cfu/ml, respectively.     

A preliminary survey on the occurrence of mycotoxigenic fungi and mycotoxins contaminating red rice at consumer level in Selangor, Malaysia

Red rice is a fermented product of Monascus spp. It is widely consumed by Malaysian Chinese who believe in its pharmacological properties. The traditional method of red rice preparation disregards safety regulation and renders red rice susceptible to fungal infestation and mycotoxin contamination. A preliminary study was undertaken aiming to determine the occurrence of mycotoxigenic fungi and mycotoxins contamination on red rice at consumer level in Selangor, Malaysia. Fifty red rice samples were obtained and subjected to fungal isolation, enumeration, and identification. Citrinin, aflatoxin, and ochratoxin-A were quantitated by ELISA based on the presence of predominant causal fungi. Fungal loads of 1.4?×?10⁴ to 2.1?×?10⁶?CFU/g exceeded Malaysian limits. Monascus spp. as starter fungi were present in 50 samples (100 %), followed by Penicillium chrysogenum (62 %), Aspergillus niger (54 %), and Aspergillus flavus (44 %). Citrinin was present in 100 % samples (0.23–20.65 mg/kg), aflatoxin in 92 % samples (0.61–77.33 μg/kg) and Ochratoxin-A in 100 % samples (0.23–2.48 μg/kg); 100 % citrinin and 76.09 % aflatoxin exceeded Malaysian limits. The presence of mycotoxigenic fungi served as an indicator of mycotoxins contamination and might imply improper production, handling, transportation, and storage of red rice. Further confirmatory analysis (e.g., HPLC) is required to verify the mycotoxins level in red rice samples and to validate the safety status of red rice.     

Purification and characterization of diamine oxidase from rice embryos

Diamine oxidase of rice seedlings has been purified 1800-fold to homogeneity. The MW of the enzyme as determined by Sephadex G-100 gel filtration was 12.3 × 10⁴ and the enzyme contained two identical subunits each with a MW of 6.12 × 10⁴. The optimal temperature and pH for the enzyme were 30° and 7.5 respectively and the enzyme followed typical Michaelis kinetics with a K_m of 10^?5 M. Each enzyme molecule contained four molecules of FAD.     

Conidia production by Isaria fumosorosea on solid substrates and its pathogenicity towards Bemisia tabaci

Large amounts of conidia must be recovered to use Isaria fumosorosea as a biological control agent. Aerial conidia are mass-produced in solid substrate culture. Conidia obtained from growth on different substrates must be similar in quantity and quality (viability, purity and virulence). In the present work, several solid substrates were evaluated: rice, sorghum, sugarcane, corncob, plantain and wheat (derived from the production of Trichogramma sp.) to find alternatives that are economical and available in different regions. The highest conidia production was obtained on rice, plantain and corncob substrates, which yielded 5.33 × 10⁹ conidia/g, 5.24 × 10⁹ conidia/g and 4.8 × 10⁹ conidia/g substrate, respectively. At concentrations of 1 × 10⁷ conidia/mL, the mortality rates obtained with conidia developed on rice, plantain and corncob substrates were 98%, 97% and 88%, respectively. The lethal concentration 50 (LC₅₀₎ values of conidia obtained from rice and plantain were 7.2 × 10⁴ conidia/mL and 5.1 × 10⁴ conidia/mL, respectively.     

Aspects of microbial heterotrophic production in a highly turbid estuary

The uptake of ¹⁴C glucose by natural microbial populations has been studied in the Severn Estuary and Bristol Channel, U.K.; the turbidity (suspended solids) in the estuary varied between < 5 mg · 1^?1 at the seaward extremity to >800 mg · 1^?1 in the estuary proper. The heterotrophic potential, V_m, was found to correlate with turbidity and particulate organic carbon but there was no correlation between microbial biomass, as assessed by plate counts, and turbidity or V_m; measurement of V_m ranged from 0.9 × 10^?4 to 288 × 10^?4μgC·1^?1·h^?1 and turnover time from <2 to >100 h. In 17 out of 42 experiments, the uptake of ¹⁴C glucose did not conform to Michaelis kinetics and in five of these experiments the data suggested that there may be a threshold of glucose concentration below which there is no uptake.     

Sporulation and toxin production by Bacillus thuringiensis var. israelensis in cadavers of mosquito larvae (Diptera: Culicidae)

Laboratory experiments with 4th-instar larvae of Aedes aegypti and Anopheles albimanus (Diptera: Culicidae) demonstrated that the entomocidal bacterium, Bacillus thuringiensis var. israelensis, can grow vegetatively, sporulate, and produce toxin in cadavers of mosquito larvae. In A. aegypti, spore counts rose from 2 × 10²/cadaver 4 hr after treatment to 1.4 × 10⁵/cadaver approximately 72 hr later, whereas in A. albimanus spore counts per cadaver increased from 2.2 × 10³ between 4 and 24 hr to 3.2 × 10⁵ at 72 hr post-treatment. Bioassays of larval cadavers indicated that toxicity associated with sporulation of B. thuringiensis var. israelensis reached a maximum level approximately 72 hr after treatment. These results demonstrate that under appropriate conditions B. thuringiensis var. israelensis can use the substrates available in larval cadavers for growth and sporulation.     

Catalytic properties of three lactate dehydrogenases from potato tubers (Solanum tuberosum)

Two l-lactate dehydrogenase isoenzymes and one dl-lactate dehydrogenase could be separated from potato tubers by polyacrylamide-gel electrophoresis. The enzymes are specific for lactate, while β-hydroxybutyric acid, glycolic acid, and glyoxylic acid are not oxidized. Their pH optima are pH 6.9 for the oxidation and 8.0 for the reduction reaction.The K_m values for l-lactate for the two isoenzymes are 2.00 × 10^?2 and 1.82 × 10^?2, m. In the reverse reaction the affinities for pyruvate are 3.24 × 10^?4 and 3.34 × 10^?4, m. Both enzymes have similar affinities for NAD and NADH (3.00 × 10^?4; 4.00 × 10^?4, and 8.35 × 10^?4; 5.25 × 10^?4, m).The dl-lactate oxidoreductase may transfer electrons either to NAD or N-methyl-phenazinemethosulfate. The K_m values of this enzyme for l-lactate are 4.5 × 10^?2, m and for d-lactate 3.34 × 10^?2, m. Its affinity for pyruvate is 4.75 × 10^?4, m. The enzyme is inhibited by excess NAD (K_m = 1.54 × 10^?4, M) and has an affinity toward NADH (K_m = 5.00 × 10^?3, M) which is about one tenth of that of the two isoenzymes of l-lactate dehydrogenase.     

Changes in the mechanical properties of the extensible cuticle of Rhodnius through the fifth larval instar

The ultimate tensile strength (σ_UT) and the modulus of elasticity (E) of Rhodnius extensible cuticle are σ_UT = 2.20 × 10⁷ Nm^?2, E = 2.43 × 10⁸ Nm^?2 (unplasticised); σ_UT = 1.43 × 10⁷ Nm^?2, E = 9.45 × 10⁶ Nm^?2 (plasticised with 5HT) and σ_UT = 9.05 × 10⁶ Nm, E = 2.46 × 10⁶ Nm^?2 (plasticised in pH 5 buffer).The mechanical properties of cuticle from insects which have deposited additional layers of cuticle after they have been fed differ from those of cuticle from unfed insects. This is possibly due to the different composition of the additional cuticle: it is suggested that the post-feeding cuticle is providing protection and a template for the next instars cuticle.The maximum strain of extensible cuticle from starved insects is related to the amount of matrix protein present.     

Structural polypeptides and products of late genes of bacteriophage Mu: Characterization and functional aspects

This paper describes the identification and functional role of late gene products of bacteriophage Mu, including an analysis of the structural proteins of the Mu virion.In vitro reconstitution of infectious phage particles has shown that four genes (E, D, I, J) control the formation of phage heads and that a cluster of eight genes (K, L, M, N, P, Q, R, S) controls the formation of phage tails.Sodium dodecyl sulphate/polyacrylamide gel electrophoresis of Mu polypeptides synthesized in Escherichia coli minicells infected by Mu phages carrying amber mutations in various late genes has resulted in the identification of the products of gene C (15.5 × 10³M_r); H (64 × 10³M_r); F (54 × 10³M_r); G (16 × 10³M_r); L (55 × 10³M_r); N (60 × 10³M_r); P (43 × 10³M_r) and S (56 × 10³M_r). Minicells infected with λpMu hybrid phages and deletion mutants of Mu were used to identify polypeptides encoded by the V-β region of the Mu genome. These are the products of genes V, W or R (41.5 × 10³M_r, and 45 × 10³M_r); U (20.5 × 10³M_r) and of genes located in the β region (24 × 10³M_r (gpgin) and 37 × 10³M_r (possibly gpmom)).Analytical separation of the proteins of the Mu virion revealed that it consists of a major head polypeptide with a molecular weight of 33 × 10³, a second head polypeptide of 54 × 10³ (gpF) and two major tail polypeptides with molecular weights of 55 × 10³ and 12.5 × 10³ (gpL and gpY, respectively). In addition, there are five minor components of the tail (including gpN, gpS and gpU) and approximately seven minor components of the head structure of the virion (including gpH).     

Production of two entomopathogenic Aspergillus species and insecticidal activity against the mosquito Culex quinquefasciatus compared to Metarhizium anisopliae

The spore productivity and insecticidal activity of two opportunistic insect pathogenic Aspergillus species (namely: Aspergillus clavatus Desmazieres and Aspergillus flavus Link (Ascomycota: Eurotiales, Trichocomaceae)) were compared to Metarhizium anisopliae sensu lato (Metchnikoff) Sorokin (Ascomycota: Hypocreales, Clavicipitaceae) for mosquito (Diptera: Culicidae) control. The production of aerial spores on wheat bran and white rice was investigated in solid-, semi-solid-, and liquid-state media supplemented with a nutritive solution. Wheat bran-based media increased the spore yield in solid-state from three to sevenfold: A. clavatus produced 48.4?±?5.2 and 15.7?±?1.6?×?10⁸ spores/g, A. flavus produced 22.3?±?4.1 and 3.1?±?2.5?×?10⁸ spores/g, and M. anisopliae produced 39.6?±?6.5 and 13.1?±?2.6?×?10⁸ spores/g of wheat bran or white rice, respectively. A. clavatus, A. flavus and M. anisopliae spores harvested from wheat bran-based solid-state media showed lethal concentrations (LC₅₀) of 1.1, 1.8, and 1.3?×?10⁸ spores/ml against Culex quinquefasciatus Say larvae in 72?h. Because A. clavatus and M. anisopliae displayed similar features when cultured under these conditions, our results suggest that insect pathogenic Aspergillus species may be as productive and virulent against mosquito larvae as a well-recognised entomopathogenic fungus.     

Levels of aflatoxin B1, bacteria and fungi in feed and food in 1971 — 1987

Totally 39% out of 8371 feed and their component samples were contaminated by aflatoxin B₁. Mean contamination was 36μg/kg with maximum yield 10100 μg/kg. Contamination of samples by total count of organisms, mean contamination and maximum yield, respectively was: 1) bacteria 99%, 2.2×10⁶, 2.4×10⁸; 2) proteolytic bacteria 94%, 1.2×10⁵, 3.0×10⁶;3) moulds 98%, 1.3×10⁵, 9.0×10⁶; 4) yeasts 44 %, 3.3×10⁴, 3.6×10⁶. The samples were contaminated in 92 % byAspergillus spp, in 71% byAspergillus flavus, in 83% byPenicillium spp, and in 20% byFusarium spp with mean contamination 8.3×104, 1.1×10³, 4.2×10⁴, 5.0×10³ , and maximum yield 6.8×10⁶, 1.0×10⁵, 5.0×10⁶, 1.5×10⁶, respectively. Totally 8.5% of strains were aflatoxinogenic and 4.4% of the strains were isolated from feed and 21 % of the strains from grain/nut.