Ail Proteins of Yersinia pestis and Y. pseudotuberculosis Have Different Cell Binding and Invasion Activities

The Yersinia pestis adhesin Ail mediates host cell binding and facilitates delivery of cytotoxic Yop proteins. Ail from Y. pestis and Y. pseudotuberculosis is identical except for one or two amino acids at positions 43 and 126 depending on the Y. pseudotuberculosis strain. Ail from Y. pseudotuberculosis strain YPIII has been reported to lack host cell binding ability, thus we sought to determine which amino acid difference(s) are responsible for the difference in cell adhesion. Y. pseudotuberculosis YPIII Ail expressed in Escherichia coli bound host cells, albeit at ∼50% the capacity of Y. pestis Ail. Y. pestis Ail single mutants, Ail-E43D and Ail-F126V, both have decreased adhesion and invasion in E. coli when compared to wild-type Y. pestis Ail. Y. pseudotuberculosis YPIII Ail also had decreased binding to the Ail substrate fibronectin, relative to Y. pestis Ail in E. coli. When expressed in Y. pestis, there was a 30–50% decrease in adhesion and invasion depending on the substitution. Ail-mediated Yop delivery by both Y. pestis Ail and Y. pseudotuberculosis Ail were similar when expressed in Y. pestis, with only Ail-F126V giving a statistically significant reduction in Yop delivery of 25%. In contrast to results in E. coli and Y. pestis, expression of Ail in Y. pseudotuberculosis led to no measurable adhesion or invasion, suggesting the longer LPS of Y. pseudotuberculosis interferes with Ail cell-binding activity. Thus, host context affects the binding activities of Ail and both Y. pestis and Y. pseudotuberculosis Ail can mediate cell binding, cell invasion and facilitate Yop delivery.     

Swabbing Often Fails to Detect Amphibian Chytridiomycosis under Conditions of Low Infection Load

The pathogenic chytrid fungus, Batrachochytrium dendrobatidis (denoted Bd), causes large-scale epizootics in naïve amphibian populations. Intervention strategies to rapidly respond to Bd incursions require sensitive and accurate diagnostic methods. Chytridiomycosis usually is assessed by quantitative polymerase chain reaction (qPCR) amplification of amphibian skin swabs. Results based on this method, however, sometimes yield inconsistent results on infection status and inaccurate scores of infection intensity. In Asia and other regions where amphibians typically bear low Bd loads, swab results are least reliable. We developed a Bd-sampling method that collects zoospores released by infected subjects into an aquatic medium. Bd DNA is extracted by filters and amplified by nested PCR. Using laboratory colonies and field populations of Bombina orientalis, we compare results with those obtained on the same subjects by qPCR of DNA extracted from swabs. Many subjects, despite being diagnosed as Bd-negative by conventional methods, released Bd zoospores into collection containers and thus must be considered infected. Infection loads determined from filtered water were at least 1000 times higher than those estimated from swabs. Subjects significantly varied in infection load, as they intermittently released zoospores, over a 5-day period. Thus, the method might be used to compare the infectivity of individuals and study the periodicity of zoospore release. Sampling methods based on water filtration can dramatically increase the capacity to accurately diagnose chytridiomycosis and contribute to a better understanding of the interactions between Bd and its hosts.     

Monitoring ovulation and implantation in the cynomolgus macaque (Macaca fascicularis) through evaluations of urinary estrone conjugates and progesterone metabolites: a technique for the routine evaluation of reproductive parameters

Investigations were undertaken to determine the applicability of recently reported specific radioimmunoassays for urinary estrone conjugates and progesterone metabolites for monitoring ovarian function in the cynomolgus macaque (Macaca fasciularis) and other macaque species. Mean estrone conjugate measurements appear to accurately reflect the preovulatory estrogen peak in both conceptive (n = 5) and nonconceptive (n = 6) cycles, as well as to indicate early pregnancy through increases which are significantly elevated by Day + 15 (p less than 0.049) post estrone conjugates peak. The mean luteal phase levels of these progesterone metabolites are significantly elevated by Day + 14 (p less than 0.012) in conceptive cycles when compared to the mean values for nonconceptive cycles.     

Toxigenic fungi associated with stored corn

A total of 246 fungal isolates were obtained from 25 moldy corn samples collected in central Iowa. Either water or ether extracts of all corn samples except one exhibited some degree of toxicity in mice and/or ducklings. At least one toxigenic isolate was obtained from each corn sample. Extracts of cultures of 99 of the fungal isolates, involving 13 genera, produced death in one or more of the assay animals. The majority of the toxigenic isolates belonged to the generaAspergillus andPenicillium. Three isolates ofTrichothecium roseum were highly toxic to ducklings and mice. The ducklings exhibited a flaccid paralysis shortly after receiving an oral dose of extracts of these three isolates. Death frequently occurred following a second oral dose given 24 hr later. Mice given intraperitoneal injections of extracts ofT. roseum first exhibited lethargy and intermittent tremors, then hyperemotivity, roughening of the hair coat, abdominal respirations, incoordination, dyspnea and clonic convulsions with death occurring usually within 10 to 20 min.

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Zusammenfassung Insgesamt sind 246 Pilzisolierungen von 25 verschimmelten Getreideproben, die in Zentral-Iowa gesammelt worden sind, erhalten worden. Sowohol Wasser- wie Aether-Extrakte von allen Getreideproben zeigten eine gewisse Toxizität in Mäusen als auch in Entchen außer einer einzigen Probe. Kulturextrakte von 99 der Pilzisolierungen, die 13 Gattungen umfaßten, verursachten den Tod in einem oder in mehreren Versuchstieren. Die Mehrheit der toxischen Isolierungen gehörte den GattungenAspergillus undPenicillium an. Drei Isolierungen vonTrichothecium roseum waren hoch toxisch für Entchen und Mäuse. Die Entchen zeigten eine schlaffe Paralyse kurz nachdem sie eine orale Dosis der Auszüge dieser drei Isolierungen erhalten hatten. Tod erfolgte häufig nach der zweiten oralen Dosis innerhalb 24 Stunden. Mäuse, die eine intraperitoneale Injektion der Auszüge vonT. roseum erhielten, zeigten erst eine Lethargie und einen intermittierenden Tremor, dann eine Hyperemotivität, aufgerauhte Haarbedeckung, abdominale Atmung, Inkoordination, Dyspnoe, klonische Zuckungen und Tod gewöhnlich innerhalb 10 bis 20 Minuten.

     

Biological effects of toxic products from Trichothecium roseum link

Extracts of rice cultures of 8 of 16 isolates ofTrichothecium roseum killed one or more ducklings or mice or both. One of the isolates (MC-156) obtained from shelled corn was the most toxigenic; extracts of this isolate killed all treated ducklings and mice.Doses of purified toxic fraction TR-1 of 166 mg/kg body weight given intraperitoneally killed all test mice but none of the mice given 100 mg/kg doses died. However, a partially purified fraction (Fraction VII), from which toxic fraction TR-1 was derived, killed two of three mice given 78 mg/kg doses.Crude ether extracts of rice cultures ofT. roseum (MC-156) produced death when injected intraperitoneally in rabbits and a 19-day-old pig and also produced dermal necrosis when applied to the skin of rabbits. The latter phenomenon was not observed when 5 mg of toxic fraction TR-1 was applied to the skin of rabbits.The greatest production of toxin occurred in rice cultures when incubated at 28° C and with 20 % (ml/g) water added to the rice. Incubation of rice cultures ofT. roseum (MC-156) under CO₂ tension suppressed toxin production.

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Zusammenfassung Auszüge von Reiskulturen von acht der 16 Stämme vonTrichothecium roseum haben mehrere Entchen und/oder Mäuse getötet. Einer der Auszüge (MC-156) von abgeschälten Mais war das toxischste; Auszüge dieses Isolates hat alle Entchen und Mäuse getötet. Dosen der gereinigten toxischen Fraktion TR-1, 166 mg/Kg Körpergewicht, intraperitonial verabreicht, haben alle Mäuse getötet, aber keine der Mäuse starb mit der Dose von 100 mg/Kg. Jedoch hat eine teilweise gereinigte Fraktion (Fraktion VII), von welcher die toxische Fraktion TR-1 gewonnen war, zwei von drei Mäusen mit 78 mg/Kg Dose getötet. Ungereinigte Ätherauszüge vonT. roseum (MC-156) waren tödlich, wenn sie in Kaninchen, in ein 19 Tage altes Schweinchen intraperitonel injiziert worden sind. Sie haben auch eine Hautnekrose hervorgerufen, wenn sie auf die Haut von Kaninchen gebracht worden sind. Das letztere Phänomen war nicht beobachtet, wenn 5 mg der toxischen Fraktion TR-1 an Kaninchenhaut gebracht worden ist. Die größte Produktion des Toxins fand in Reiskulturen statt, wenn sie bei 28° C und mit 20 Perzent (ml/g) Wasser bebrütet worden sind. Inkubation von Reiskulturen vonT. roseum (MC-156) unter CO₂-Druck hat die Toxinproduktion unterdrückt.

     

Pregnant mares' serum gonadotropin source influences fertilization and fresh or thawed embryo development,but the effect is genotype specific

The influence of the source of pregnant mares' serum gonadotropin (PMSG) on the num ber, quality, and in vitro development of mouse embryos before and after freezing was evaluated among three genotypes: N:NIH(S), C57BL/6N, and C3H/HeN-MTV^?. Immature females were given PMSG from one of five commercial sources. Following col lection ( 116 hr later), embryos were evaluated for stage of development, and four-to eight-cell embryos were pooled within genotype and assigned to standardized fresh or freeze-thaw culture trials. Different PMSG sources stimulated the production of different num bers of total embryos (P < 0.05) but not necessarily more embryos suitable for freezing. Differences in embryo production among genotypes indicated that absolute embryo num bers using a single mouse genotype may not accurately reflect the potency of a specific gonadotropin source. The PMSG source also affected the ability of an embryo to survive in culture either immediately after collection or after frozen storage. The effect, however, was genotype specific, with some mouse strains being relatively insensitive to PMSG source, whereas gonadotropin source played a major role in determining in vitro viability in others. Development rates for freshly collected embryos differed, often inconsistently, from those of thawed embryos regardless of the PMSG source used, demonstrating that fresh embryo development cannot be used to estimate expected post-thaw survival. In vitro development of thawed embryos is influenced not only by genotype, but also the source of the gonadotropin used to promote follicular development and oocyte maturation. These findings may explain, in part, the wide variation in embryo viability and culture rates reported among laboratories and intraspecies animal populations.     

Combined Expression of Aspergillus nidulans Endoxylanase X24 and Aspergillus oryzae (alpha)-Amylase in Industrial Baker's Yeasts and Their Use in Bread Making

The Aspergillus nidulans endoxylanase X24 and the Aspergillus oryzae (alpha)-amylase cDNAs were placed under the control of the Saccharomyces cerevisiae actin promoter (pACT1) and introduced into baker's yeast. Bread made with transformants expressing both enzymes (YEpACT-AMY-ACT-X24) showed a 30% increase in volume and reduced firmness in comparison with that produced with a commercial strain. Endoxylanase X24 and (alpha)-amylase seem to act synergistically to improve the quality of bread in terms of volume and density.     

Chromosome localization and characterization of a family of long interspersed repetitive DNA elements from the genus Zea

This paper describes the characterization and chromosomal distribution of new long repetitive sequences present in all species of the genus Zea. These sequences constitute a family of moderately repetitive elements ranging approximately from 1350 to 1700 copies per haploid genome in modern maize (Zea mays ssp. mays) and teosinte (Zea diploperennis), respectively. The elements are long, probably larger than 9 kb, and they show a highly conserved internal organization among Zea subspecies and species. The elements are present in all maize chromosomes in an interspersed pattern of distribution, are absent from centromeric and pericentric heterochromatin, and with some clustering in the distal regions of chromosome arms.