A genetic study of tolerance and resistance to colicin A inCitrobacter freundii

Colicin A-insensitive mutants ofCitrobacter freundii were isolated and grouped into six phenotypic classes characterized by sensitivity, insensitivity or partial insensitivity to the bacteriocins S6, DF 13 and colicin A, and sensitivity or insensitivity to deoxycholate (DOC) and ampicillin. Mapping by the gradient-of-transmission method revealed the chromosomal regions in which the responsible genes are situated. Res-3 mapped nearpur betweenpur andthr; Tol-5 mapped betweenaro andilv and Tol-4 betweengal andpyr; Tol-1, Tol-2 and Tol-3 are situated close togal. All the mutations that mapped neargal rendered the bacteria more sensitive to DOC and ampicillin. Complementation analysis withE. coli plasmids showed that the three phenotypic groups that map neargal were complemented byE. coli plasmids and fall into three complementation groups. Two of these are equivalent with thetol A andtol B genes inE. coli.     

Studies of the morphology of chromosomes of some selected species

Karyotypes of twelve species from twenty-four localities in southern Moravia and one locality in Slovakia were investigated. Their counts or karyotypic formulae are as follows:Chenopodium foliosum (Moench) Ascherson: K (2n)=18=16 A^m+2 B^sm;Astragalus austriacus Jacq.: K (2n)=16=8 A^m+8 B^sm;Astragalus exscapus L.: K (2n)=16=10 A^m+4 B^sm+2 C^st;Astragalus cicer L.: K (2n)=64;Astragalus onobrychis L.: K (2n=64 and K (2n)=64+1;Vicia dumetorum L.: K (2n=14=10 A^m+4 B^sm;Vicia sylvatica L.: K (2n)=14=2 A^m+10 B^sm+2 C^st;Vicia pisiformis L.: K (2n)=12=8 A^m+4 B^sm;Vicia cassubica L.: K (2n)=12=4 A^m+6 B^sm+2 C^st;Vicia cracca L. (from five localities in southern Moravia): K (2n)=28=4 A^m+12 B^sm+12 C^st and K (2n)=28+1=5 A^m+12 B^sm+12 C^st;Vicia cracca L. (from one locality in Slovakia): K (2n)=14=2 A^m+6 B^sm+6 C^st;Vicia tenuifolia Roth: K (2n)=24=4 A^m+16 B^sm+4 C^st;Serratula lycopifolia (Vill.) Kern.: K (2n)=60.     

Isolation and characterization of the four major cysteine-proteinase components of the latex of carica papaya L. reactivity characteristics towards 2,2′-dipyridyl disulfide of the thiol groups of papain,chymopapains A and B,and papaya peptidase A

High-quality spray-dried latex of Carica papaya L was fractionated by using SP-Sephadex-C50. The four major cysteine-proteinase components—papain(E.C.3.4.22.2), chymopapains A and B(jointly designated currently as E.C.3.4.22.6), and papaya peptidase A—were isolated and characterized by protein chemical methods and by study of their thiol groups using2,2′-dipyridyl disulfide as a two-protonic-state titrant and reactivity probe. Papain and papaya peptidase A each contain one thiol group/molecule, which in each case is part of the catalytic site, as evidenced by high reactivity toward2,2′-dipyridyl disulfide in acidic media. Chymopapains A and B each contain two thiol groups/molecule, only one of which is essential for catalytic activity. The reactivities of the thiol groups of these enzymes toward2,2′-dipyridyl disulfide at pH4 and10 and activity loss analysis by Tsou Chen-Lu plots each provides a ready means of distinguishing among the four cysteine proteinases. The nonessential thiol groups of chymopapains A and B readily undergo irreversible oxidation. The reactivity characteristics of the essential thiol groups of the four enzymes suggest the presence of somewhat similar interactive cysteine-histidine catalytic center systems in papain, papaya peptidase A, and chymopapain B but a different type of catalytic center environment in chymopapain A.     

Pacemakers in aggregation fields of Dictyostelium discoideum: does a single cell suffice?

In this paper we address the following question: can a single cell of the cellular slime mold Dictyostelium discoideum serve as a pacemaker for the aggregation phase? Whether or not this is possible is determined by the relative importance of cyclic AMP production due to self-stimulation as compared to diffusion of cyclic AMP away from the cell and extracellular degradation. We determine the conditions under which a single cell on an infinite place can emit periodic signals of cyclic AMP using a model developed previously for signal relay and adaptation in Dictyostelium. Elsewhere it has been shown that this model provides an accurate representation of the stimulus-response behavior of Dictyostelium for a variety of experimental conditions.     

6-phosphogluconate dehydrogenase activity variants inMusca domestica L.: A further allele at thePgd locus as proved by densitometric assay

A new electrophoretic variant of 6-phosphogluconate dehydrogenase (6PGD) has been detected in flies of a laboratoryMusca domestica strain. This variant is to be added to the two already described, PGD-A and PGD-B, identified by a fast-weak and a slow-thick electrophoretic band, respectively. The new variant, PGD-C, has the same mobility as PGD-A but provides a more intensely stained band; therefore it can be described as a fast-thick phenotype. The staining intensity of PGD-C is slightly lower than that of PGD-B. Genetic and densitometric tests have shown that the different levels of enzymatic activity of the two fast variants A and C are inherited as alternative genetic units, and they have been interpreted as one aspect of the phenotypic expression of twoPgd alleles, namely,Pgd ^A andPgd ^C. These alleles determine both the rates of electrophoretic mobility (fast in both cases) and the levels of activity (low for A, strong for C; shown by weak or thick stained electrophoretic bands). Similarly, the two distinctive features of PGD-B, namely, slow mobility and high activity level, are always jointly inherited and appear as two pleiotropic aspects of the phenotype coded for by thePgd ^B allele. ThePgd ^B/Pgd^C heterozygous flies provide a slightly asymmetrical three-banded zymogram, while thePgd ^A/Pgd^C combination leads to a single-banded pattern, showing the same mobility as the parents and an intermediate staining intensity. The quantitative analysis of enzyme activity of 6PGD zymograms, performed through densitometric methods, has led to the recognition of three different activity levels coded for byPgd alleles, one of which, namely,Pgd ^C, would not have been detected using electrophoretic methods alone.     

The effect of N-nitroso-N-methylurea,buthylmethane sulphonate and x-rays on the germination and production of chlorophyll mutations in einkorn wheat

Grains ofTriticum monococcum L. var.sofianum Körn. were treated with O.1 mM, 0·2 mM and 0·3 mM solutions of N-nitroso-N-methylurea (MNtt), with 0.03 M solution of buthylmethane sulphonate (BMS) and with X-rays in doses of 5 000r and 10 000r. The germination and development of individual colors of chlorophyl mutants were observed by the system developed byLamprecht (1960). All the mutants induced were classified according to their color changes into three main categories-homogenous unicolor, homogenous multieolor and heterogenous multieolor. In the last type the colors of individual leaves of the same plant varied. Anthocyanin mutations “albina” and “albino-transvirgata” sometimes coincided with the chlorophyll mutations. Some chlorophyll mutations showing complicated groups of colors appeared which were beyond the scale of classification by ordinary systems. The largest proportion in the spectrum of chlorophyll mutations, induced by MNH and X-rays was occupied by mutations of thealbina type. The broadest mutation spectrum in our experiments was induced by the application of 0.3 mM MNH. The doses of X-rays used induced relatively higher numbers of albina-type chlorophyll mutations than MNH and BMS. In our experiments we succeeded in inducing on medium size samples ofTriticum monococcum L. var.sofianum Körn not only almost all types of chlorophyll mutations, induced byFuji (1960, 1962) andMatsumura (1960), but in addition also a great number of other even more complicated chlorophyll mutations, which have never been previously described inTriticum monococcum. L.     

The effect of N-nitroso-N-methylurea,buthylmethane sulphonate and X-rays on the germination and production of chlorophyll mutations in einkorn wheat

Grains ofTriticum monococcum L. var.sofianum Körn. were treated with 0·1mm, 0·2mm and 0·3mm solutions of N-nitroso-N-methylurea (MNH), with 0·03m solution of buthylmethane sulphonate (BMS) and with X-rays in doses of 5 000r and 10 000r. The germination and development of individual colors of chlorophyl mutants were observed by the system developed byLamprecht (1960). All the mutants induced were classified according to their color changes into three main categories-homogenous unicolor, homogenous multicolor and heterogenous multicolor. In the last type the colors of individual leaves of the same plant varied. Anthocyanin mutations “albina” and “albino-transvirgata” sometimes coincided with the chlorophyll mutations. Some chlorophyll mutations showing complicated groups of colors appeared which were beyond the scale of classification by ordinary systems. The largest proportion in the spectrum of chlorophyll mutations, induced by MNH and X-rays was occupied by mutations of thealbina type. The broadest mutation spectrum in our experiments was induced by the application of 0·3mm MNH. The doses of X-rays used induced relatively higher numbers ofalbina-type chlorophyll mutations than MNH and BMS. In our experiments we succeeded in inducing on medium size samples ofTriticum monococcum L. var.sofianum Körn not only almost all types of chlorophyll mutations, induced byFujii (1960, 1962) andMatsumura (1960), but in addition also a great number of other even more complicated chlorophyll mutations, which have never been previously described inTriticum monococcum. L.     

Pyramiding Bt genes for increasing resistance of cotton to two major lepidopteran pests: Spodoptera litura and Heliothis armigera

To more effectively control two major cotton insects (cotton bollworm and Spodoptera litura) and improve the efficacy of the pest resistance management, novel transgenic plants expressing Bacillus thuringiensis Cry9C gene were generated, and gene stacking strategy was incorporated. Initially, a binary plasmid vector harboring Cry9C gene was introduced into an elite cotton cultivar Simian-3 by Agrobacterium-mediated transformation. Integration and expression of the Cry9C genes in three transgenic lines were confirmed by PCR and RT-PCR. Among these transgenic lines, T0 generation of line 16 (L-16) with normal phenotypes were selected by ELISA assays for its highest expression level of Cry9C. In T1 population of L-16, the expression level of Cry9C ranged from 29 to 45 μg/g fresh leaf. The following insect bioassays demonstrated that transgenic S3-35S::Cry9C cotton plants exhibited moderate toxicity to Heliothis armigera but strong toxicity to S. litura compared with the transgenic plants expressing Cry 1Ac gene. For incorporation of gene staking strategy, Cry9C gene and Cry 2A or Cry 1Ac were pyramided, respectively by sexual crossing. The expression of Cry9C protein in all F1 progenies had a similar level as the parent plants indicating the high heritability of Bt genes in transgenic progenies. Progenies from both Cry9C × Cry 2A and Cry9C × Cry 1Ac exhibited higher resistance to S. litura compared with their parents. Together our data demonstrated that our newly generated transgenic plants represent a reservoir of novel insect-resistant materials in cotton breeding, and the successful incorporation of gene pyramiding technology can provide a new solution of developing multiple resistance management strategies.     

The establishment ofAnagyrus saccharicola Timb. [Hymenoptera: Encyrtidae] in Barbados,West Indies,against the sugarcane mealybug,Saccharicoccus sacchari (Ckll.) (Hemiptera: Coccidae]

During the survey of the natural enemies ofSaccharicoccus sacchari in Barbados in 1968 and 1969, the following six indigenous species of natural enemies were recorded: —Hyperaspis trilineata andNephus sp.(Coccinellidae); Oligota barbadorum (Staphylinidae); an unidentified Cecidomyid(Cecidomyidae); Pseudaphycus mundus (Encyrtidae) andAspergillus sp. (Aspergillacae). Of these,H. trilineata was found in fair numbers in the Westmoreland (St. James) area only;Aspergillus sp. was more abundant during the wet season, while the other species were recorded usually in small numbers from most parishes. As the indigenous natural enemies do not provide effective control of the pest, three exotic predators and one parasite were introduced into Barbados, through the Commonwealth Institute of Biological Control.Cryptolaemus montrouzieri, Hyperaspis sp. andNephus sp. were obtained from India andAnagyrus saccharicola from East Africa. OnlyA. saccharicola became established. It was recovered soon after its release and, augmented by additional releases, spread rapidly. In January 1972, the levels of parasitism in the dry, intermediate and high rainfall areas were: 8.3, 9.0 and 9.7%.     

C banding treatment for the chromosomes of some gymnosperms

An advanced method of C banding treatment for the chromosomes of gymnospermous plants was developed by modification of the conventional C banding method. All of the three species investigated, i.e.Cycus revoluta, Ginkgo biloba andPinus densiflora, showed clear C bands in the interphase and metaphase chromosomes. The three species were found to differ from each other with respect to number and occurrence of C bands.     

Leaf flavonoids ofGalium sect.Aparinoides (Rubiaceae)

13 taxa belonging to 4 “species groups” ofGalium L. sect.Aparinoides (Jord.)Gren. produce 15 leaf flavonoids: Apigenin-7-diglucoside, Luteolin-7-monoglucoside and 7-diglucoside, Diosmetin, Diosmetin-7-monoglucoside and 7-diglucoside; Kaempferol-3-rutinoside, Kaempferol-3,7-diglucoside, Quercetin, two Quercetin-3-monoglycosides, Rutin, Quercetin-3-rutinoside-7-glucoside, Quercetin-7-glycoside and an unidentified aglycone. TheG. trifidum, G. obtusum andG. palustre groups (with the exception of theG. tinctorium subspecies andG. elongatum) have similar flavone-flavonole patterns, while theG. antarcticum group produces a specific pattern. Leaf flavonoids of theG. trifidum andG. antarcticum group are inhomogenous, becauseG. tinctorium subsp.tinctorium andG. antarcticum lack flavones. For all taxa (with the exception of those of theG. antarcticum group) intraspecific variation is demonstrated, and 4 populations ofG. trifidum subsp.trifidum, G. tinctorium subsp.tinctorium,G. obtusum subsp.obtusum andG. labradoricum even exhibit intrapopulation variation. The implications of flavonoid data on the systematics and the astonishing intrapopulation and intraspecific variation are discussed.     

Inactivation of the phosphoglucomutase gene pgm in Paenibacillus polymyxa leads to overproduction of fusaricidin

Fusaricidin, a lipodepsipeptide isolated from Paenibacillus polymyxa, has high antimicrobial activity against fungi and Gram-positive bacteria. Through mutagenesis, we obtained two mutant strains, N1U7 and N17U7, which produce 6.2- to 7.9-fold more fusaricidin than their parent strain. Causal mutations were identified by whole-genome sequencing, and the two strains each contained at least eleven point mutations, including four common mutations. A mutation in the PPE04441 gene (pgm), encoding an α-phosphoglucomutase, was found to be an important factor in fusaricidin overproduction by complementation experiments. Null mutation of pgm in the parental strain increased fusaricidin production by 5.2-fold. Increased growth and cell viability in stationary phase, reduced exopolysaccharide production, and increased fusA expression were observed in the pgm mutant strains, which might be related to fusaricidin overproduction. This is the first report revealing that PGM deficiency leads to an overproduction of fusaricidin.     

Parasites ofSpodoptera exigua,S. eridania [Lep.: Noctuidae] andHerpetogramma bipunctalis [Lep.: Pyralidae] collected fromAmaranthus hybridus in field corn

Three species of lepidopterous larvae were collected fromAmaranthus hybridus L. growing in field corn during 1975 and 1976 at Hastings, Florida.Spodoptera exigua (Hubner) was the predominant species in May.Spodoptera eridania (Cramer) was predominant in June andHerpetogramma bipunctalis (F.) in July and August. Nine native species of parasites, representing theBraconidae, Eulophidae, Ichneumonidae andTachinidae, emerged from these larvae.Meteorus autographae Muesebeck emerged from bothS. exigua andS. eridania. TheTachinidae, Winthemia rufopicta (Bigot),Eucelatori rubentis (Coquillett) andLespensia sp., emerged from mixtures ofS. exigua andS. eridania. Apanteles marginiventris (Cresson),Temelucha sp., andChelonus texanus Cresson emerged from bothS. exigua andH. bipunctalis larvae, andEuplectrus platyhypenae Howard andOphion sp. emerged fromS. eridania. All the species of parasites from the lepidopterous larvae that feed onAmaranthus hybridus are also reported as parasites ofS. frugiperda, a serious pest of corn. Therefore these larvae onA. hybridus may be a source of the parasites found attackingS. frugiperda.     

Censusing primate populations in the reserved area of the Pacaya and Samiria Rivers,Department Loreto,Peru

Four expeditions were made from February 1973 through March 1974 to the Samiria and Pacaya Rivers, which drain the zone between the Lower Ucayali and Huallaga/Marañón, principal constituents of the Amazon. This area is protected as part of the management program for the fishing ofArapaima gigas; however, there has been chronic hunting pressure from poachers, the government's guardians, and sailors, and, recently and most importantly, the petroleum exploration workers. Strip-censusing is extensively discussed. We employed a combination of three techniques: observations from our boat, observations from canoe or on foot, and intensive work in an area with mapped trails (Maldonado Peninsula, Samiria River). The Middle Samiria and Middle Pacaya were faunally the most rewarding. Relatively abundant wereSaimiri sciureus, Alouatta seniculus, probablyPithecia monachus, andSaguinus (probablyfuscicollis illigeri); somewhat less so wereCebus apella (often associated withSaimiri) andC. albifrons; Lagothrix lagotricha required deeper penetration, andAteles is seriously threatened (A. paniscus was seen andA. belzebuth was reported present). Also reported present wereAotus trivirgatus, Cebuella pygmaea, andCallicebus moloch andC. torquatus, though the latter two species may have been confused. Crude density estimates were developed from the Maldonado Peninsula data.     

Mould and mycotoxin contamination of stored corn in Turkey

A total of 167 corn samples, including imported and locally grown corn, were obtained from various regions and store houses in Turkey and surveyed for mould occurrence and mycotoxin content. The mould contamination level was 10⁵ — 10⁶ colonies/g.A. flavus, A. niger, F. oxyporum, P. variable, andRhizopus spp. However, the dominant flora showed significant differences between the imported and domestic corns. Afiatoxin B₁ was found in 16 % of the samples ranging from 2–74μg/kg. Ochratoxin A and sterigmatocystin were found at minimum detection levels. Mycotoxin production characteristics of mould isolates were also determined.     

Germination and mitochondrial damage in spores of Dictyostelium discoideum following supraoptimal heating

Spores of Dictyostelium discoideum may be quantitatively activated with a heat treatment of 45°C for 30 min. Heat activation at either higher temperatures or for longer duration at 45° C resulted in damaged spores. The spores showed an increased postactivation lag time at 23°C and an increased inability to respond to deactivation with 0.2 M sucrose. As the severity of supraoptimal heating increased, a greater percentage of the spores appeared to contain phase dark lesions and to lose viability. Oxygen uptake began to decrease during and after the appearance of the lesions. Using electron microscopy, the phase dark lesions were found to be mitochondria with disrupted cristae.