Tremorgenic mycotoxins produced by strains of Penicillium spp. isolated from toxic Poa huecu parodi

Seventeen strains of Penicillium spp. have been isolated from Poa huecu Parodi from the Zapala zone, exhibiting toxicity to sheet. The following strains have been identified: P. crustosum, cyclopium, notatum, palitans, puberulum, verrucosum, viridicatum and Penicillium spp. The toxigenic capacity of the strains was studied after growing them under suitable conditions. Toxins produced were analysed by thin layer chromatography (TLC). Penitrem A (PA) and Penitrem B (PB) neurotoxins were identified and quantitated in twelve strains; verruculogen (VERR) and fumitremorgen B (FTB) being present in one of them. The effect of these mycotoxins was studied in mice. Neurological symptoms characteristic of the intoxication by tremorgenic toxins and similar to those observed in sheep suffering from huecu's disease were observed. The possible role of these toxins as causative agents of huecu's disease is discussed.     

The frequency of marker changes in sugarcane plants regenerated from callus culture

This study investigates the frequency of apparent and permanent expression of marker change following two types of tissue culture, conventional callus and direct regeneration cultures, and for two markers it relates this frequency to that following breeding. Each clone was used for only one marker. After conventional callus culture, plants of the sugarcane clone Arundoid B, a clone having a growth habit with shortened internodes and leaves, were freed of this marker at a rate of 1 in 172 plants. Marker remission in a second clone with a leaf blotch was enhanced in the presence of a mutagen. Callus culture alone gave a remission rate of 1/280 plants, while treatment of callus with ethyl methanesulfonate gave a remission rate of 1/42 plants. Of two markers subjected to vegetative and sexual transmission, the first, a leaf marker, was stable in callus culture with no remissions; crossing with non-marker parents produced progeny with 54% lacking the marker. The second, a stalk marker (multibud), showed epigenetic effects during two generations of vegetative propagation; plants lacking the multibud marker produced vegetative progeny in which the marker reappeared. Nine crosses to nonmarker parents produced progeny of which an average of 29% had the marker. The use of stalk chimeras as markers demonstrated that passage through conventional callus or direct regeneration culture resulted in the loss of the donor phenotype in all plants regenerated. Phenotypic variation in plants derived from callus culture appears to arise from several sources; chimeral segregants, epigenetic transients, and mutational variants.     

Analysis of the molecular mass heterogeneity of the transferrin receptor in Neisseria meningitidis and commensal Neisseria

Peroxidase-conjugated transferrin was used to detect transferrin receptors both in intact outer membrane vesicles (OMVs) from Neisseria species in a dot blot assay, and in SDS-PAGE-separated OMV proteins after transferring to nitrocellulose membranes. All N. meningitidis strains produced transferrin receptors after culturing in either iron sufficiency or iron restriction although expression was higher in the latter case, whereas only six N. lactamica and two N. sicca (among 20 commensal species) were able to bind transferrin. Molecular mass (MM) of the receptors were mainly between 78 kDa and 85 kDa (87.5% of strains), 12.5% had receptors with MM close to 70 kDa, and 5% showed receptors with MM over 85 kDa. Our results confirm the molecular mass heterogeneity of the transferrin receptors in N. meningitidis, completely disagree with the 'universal' 98 kDa receptor proposed by some authors, and show a low expression of the receptor in commensal Neisseria.     

Experiments with trap crops against African bollowrm, Heliothis armigera, in Ethiopia

In a 1 ha haricot bean (HB) (Phaseolus vulgaris L.) field strip-cropped with 2 rows of maize (MZ) (Zea mays L.) on either side and then at 25 m intervals, the number of African bollworm (ABW) (Heliothis armigera (Hubner) (Lepidoptera: Noctuidae)) eggs + larvae on MZ was higher than that on HB by a factor of nearly 18. In a replicated experiment where five trap crops were compared with HB, as a check, all of them contained significantly greater numbers of ABW eggs + larvae than the check. Among the crops tested, lupin (LP) (Lupinus termis Forsk.) and pigeon pea (Cajanus cajan (L.) Millsp.) followed by hyacinth bean (Dolichos lalab L.) contained the highest ABW egg + larval population while sunflower (Helianthus annuus L.) contained the lowest; MZ was intermediate. On the other hand, HB plots bordered with MZ suffered significantly lower percent pod damage by ABW than did the check. Although grain yield differences among treatments were not significant, MZ-bordered plots gave nearly 22% higher yield than the check during the heavy ABW infestation in 1982. These differences were less obvious during the 1983 season because of low ABW infestation. In hot pepper (Capsicum spp.) strip-cropped with lupin, egg + larval counts on the latter were greater by a factor of nearly four in 1981 and 18 in 1982. It is concluded that trap-cropping has a great potential in the integrated management of ABW.

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Résumé En 1981, dans un champ de haricot (Phaseolus vulgaris), des cultures pièges de maïs (Zea mays) ont été semées en rangs doubles tous les 25 m et de chaque côté du champ, soit un total de 5 rangs doubles. Le nombre d'H. armigera (oeufs + chenilles) a été près de 18 fois plus élevé sur maïs que sur haricot.En 1982 et 1983, l'attractivité de 5 cultures pièges: Dolichos lablab, Lupinus termis, Z. mays, Cajanus cajan et Helianthus annuus, a été comparée à celle du haricot. Toutes ces plantes portaient un nombre d'oeufs et de chenilles supérieur au témoin (P. vulgaris). L'ordre décroissant des contaminations était: L. termis, C. cajan, D. lablab, Z. mays et H. annuus. Les rangs de P. vulgaris bordés par des rangs de Z. mays étaient moins contaminés que les témoins. Bien que les différences de rendements en graines suivant les expériences n'aient pas été significatives, les parcelles bordées de maïs ont fourni une récolte supérieure de 22%, pendant l'année 1982, où la contamination par H. armigera a été forte. En 1983, où l'infestation a été faible, les différences étaient moins claires.En 1981 et 1982, 5 rangs de L. tremis à 25 m d'intervalle ont été utilisés comme pièges pour protéger le piment fort (Capsicum spp.). Les décomptes d'oeufs et de chenilles ont été respectivement près de 4 et 18 fois plus élevés.La conclusion est que les cultures pièges ont un grand avenir dans la lutte intégrée contre H. armigera.

     

Aspects of the life history of Cercopithifilaria johnstoni (Nematoda:Filarioidea)

and 1988. Aspects of the life history of Cercopithifilaria johnstoni (Nematoda:Filarioidea). International Journal for Parasitology 18: 1087–1092. Cercopithifilaria johnstoni (Nematoda:Filarioidea) occurs in the subcutaneous connective tissues of a spectrum of native murid and marsupial hosts in Eastern Australia. Life cycle studies revealed that: (i) microfilaria occur in lymphatic capillaries and extravascular connective tissue of the dermis (= ‘skin-inhabiting’), (ii) ixodid ticks, particularly Ixodes trichosuri, are intermediate hosts in nature, (iii) development from microfilariae to infective third-stage larva occurs only while the tick is off the host, that is, during ecdysis from larva to nymph or from nymph to adult. Transmission of C. johnstoni in a wild population of bush rats (Rattus fuscipes) occurred in summer and winter, and was associated with peaks in the number of larval and/or nymphal stages of ticks on rats. C. johnstoni was transmitted experimentally to bandicoots (Isoodon macrourus, Perameles nasuta), bush rats and laboratory rats (R. norvegicus), indirectly by subcutaneous inoculation of third-stage larvae and directly by tick feeding. The prepatent period was approximately 3 months and the longest duration of microfilariae in the ‘ skin’ was more than 25 months. Dermal and ocular lesions were observed in R. fuscipes. The host-parasite relationship has the potential for development as an inexpensive and practical model for human onchocerciasis.     

Population differences in larval hostplant use in the checkerspot butterfly, Euphydryas chalcedona

Larvae from two populations of Euphydryas chalcedona Doubleday & Hewitson (Nymphalidae) were reared on their own hostplant and that of the other population, in both pre-diapause and post-diapause instars. One population, Chico, uses Penstemon breviflorus Lindl. (Scrophulariaceae), and the other, Echo Lake, uses P. newberryi Gray. Growth rate and survival were determined for pre-diapause and post-diapause larvae from both populations on both plant species; and digestive efficiencies were calculated during the prediapause instars. The results showed that larvae from the two populations differed in their responses to the two plant species. Pre-diapause larvae from Chico performed equally well on both plant species—survival and digestive indices were not significantly different for two Penstemon species. In contrast, pre-diapause larvae from Echo Lake performed significantly worse on the non-hostplant—growth and survival were significantly lower on the non-host, P. breviflorus. In addition, comparison of digestive efficiencies for the two plants showed that larvae from Echo Lake digested P. breviflorus better than P. newberryi, but were significantly less able to convert P. breviflorus to body mass. In the post-diapause instars, larvae from Chico grew faster on the host than on the non-host. Larvae from Echo Lake grew quite slowly on both plant species and significantly more of the Echo Lake larvae returned to diapause instead of completing development.

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Résumé Des chenilles de deux populations d'E. chalcedona ont été élevées sur leur propre plante-hôte et sur celle de l'autre population, aux stades avant et après diapause. Les deux populations s'alimentent sur différentes espèces de Penstemon (Scrophulariaceae), et une population—Echo Lake—est monophage sur P. newberry, tandis que l'autre—Chico—utilise d'abord P. breviflorus, mais les chenilles après diapause sont trouvées sur au moins deux autres espèces de plantes. Les taux de croissance et de survie ont été déterminés pour des chenilles avant et après diapause pour les deux populations sur les deux plantes; les efficacités digestives ont été calculées sur les chenilles avant diapause.Les résultats ont montré que les chenilles des deux populations différaient par leur degré de spécialisation digestive sur leur plante hôte normale: les chenilles de Chico ont utilisé aussi bien les deux plantes, tandis que celles d'Echo Lake le faisaient significativement moins bien sur la plante non-hôte, par suite de l'inaptitude à la digérer. Ainsi la population oligophage est alimentairement moins spécialisée et plus capable de se débrouiller avec une plante non-hôte. Après diapause, les chenilles de Chico s'alimentaient significativement mieux sur plante hôte que non-hôte, ce qui était le cas aussi pour la population monophage. Dans l'ensemble, les chenilles de la population monophage semblaient moins capables de se débrouiller dans des conditions défavorables ou moins avantageuses.

     

Seed dispersal and seedling emergence in an old field community in central New York (USA)

Summary Seed dispersal and seedling emergence of common taxa growing in a Solidago-dominated old field in central New York (USA) were monitored from May 1982 to June 1984. Over 3.5x10⁴ seeds per m² were captured on seed traps in each of the two years, with peaks occuring in July (due to Hieracium) and in November (due to Solidago). About 4.0x10³ seedling/m² emerged beneath the intact community in each of the two years. Although seedlings emerged predominantly in the early spring, a secondary peak occurred in September and October when many seedlings of introduced grasses appeared. Two additional aspects of the reproductive biology of the major taxa were related to the seasonal timing of seed dispersal: As the date of peak seed dispersal (among taxa) became progressively later in the season, (1) the duration of dispersal increased from about one week to about one-half year, and (2) the delay between the peak of seed dispersal and the peak of seedling emergence increased from a few days to about one-half year.     

Forest succession in the subalpine region of Mt. Fuji,Japan

Subalpine forest succession was studied on Mt. Fuji, Japan, where various types of forests in different successional phases occur owing to volcanic action. Ninety stands were subjected to ordination using an index (SI) defined by the relative basal area and the life span of component woody species, and the cover of canopy layer of the sample stands. Two different sequences of sample stands were found. One was from deciduous scrubs, through Larix kaempferi forests and Abies forests, to Tsuga diversifolia forests, and the other from Abies-Tsuga thickets to Abies forests. Through analyses of the forest structure and composition, soil survey and identification of fallen logs, the former sequence was recognized as the primary sere and the latter as a regeneration sere following gap formation. During forest succession, basal area reached a maximum in the seral phase with a multi-layered structure. The Tsuga forests, whose understory is restricted to a moss layer, were regarded as the climax. The death or fall of Tsuga stems resulted in gaps, which were subsequently occupied by Abies-Tsuga thickets. The second Abies forests were distinguished from the ones in the primary sere by the occurrence of Dryopteris and Cacalia and the lack of Rhododendron in the understorey. Both Abies forest types included Tsuga saplings. Thus, a cyclic relation is supposed between Abies and Tsuga.Nomenclature follows Ohwi (1975) and Nakaike (1982) for vascular plants, Iwatsuki & Noguchi (1973) for mosses, Inoue (1981) for hepaticae, Kashiwadani (1981) for lichens, respectively. Abies veitchii, A. mariesii were lumped as Abies spp.I wish to express my sincere gratitude to Prof. Toshio Hamaya, Tokyo, for the cordial guidance and encouragement. I also thank Prof. M. Numata and Dr. M. Ohsawa, Chiba, Prof. K. Okutomi, Tokyo, Dr. K. Suzuki, Tokyo, Dr. M. Suzuki, Kanazawa, and Mr. H. Taoda, Kumamoto, for their valuable advice and discussions.     

Regulatory and molecular properties of citrate synthases from methylotrophs

Abstract Gram-negative methylotrophs contain a high- M _r'large' citrate synthase. Gram-positive methylotrophs, on the other hand, contain a 'small' citrate synthase. These differences in M _r coincided partly with differences in NADH sensitivity. Citrate synthases from obligate Gram-negative and Gram-positive facultative methylotrophs were insensitive to feedback inhibition by NADH; only the enzymes from Gram-negative facultative methylotrophs were inhibited by NADH.     

Interspecific crosses inHordeum (Poaceae)

A crossing programme including 30 species and 40 cytotypes within the genusHordeum was undertaken. Viable hybrids were obtained in 302 combinations, 15 of which were intraspecific. Differences in seed set and in germination were observed in crosses between different groups of species. Obtaining crosses between different taxonomic groups was generally more difficult when diploid material was used. Some species, e.g.,H. lechleri, H. jubatum, andH. brachyantherum showed a higher crossability than others. The chromosome numbers of the hybrids were usually those expected from the parental numbers but aneuploid series around the expected numbers were rather frequent. Three cases of unreduced gametes were found. Selective chromosome elimination was restricted to combinations including eitherH. vulgare orH. bulbosum.—Despite a very diverse morphology, all South American diploid species together with the two North American diploidsH. intercedens andH. pusillum appear to be closely related. The hexaploid American speciesH. procerum, H. lechleri, andH. arizonicum are also related. The two North American tetraploid speciesH. jubatum andH. brachyantherum sometimes form semifertile hybrids. The Asiatic speciesH. roshevitzii appears to be related to both North and South American taxa.