Importance of the galE gene on the virulence of Pasteurella multocida

The galE gene of Pasteurella multocida has been isolated by complementing galE-defective mutants of Salmonella typhimurium with a plasmid library of this organism. The complete nucleotide sequence of the P. multocida galE gene consists of 1017 nucleotides, encoding a predicted polypeptide of 339 amino acids. The deduced amino acid sequence displayed the highest identity (85%) to the GalE protein of Haemophilus influenzae. However, the gene organization surrounding the galE locus was different from that of H. influenzae. A galE-defective mutant of P. multocida was obtained by replacement of the active galE gene by a copy inactivated in vitro. The resulting galE mutant was highly attenuated as seen in a biological test carried out in a mouse model.     

Studies of the transmissibility of the agent of bovine spongiform encephalopathy to the domestic chicken

Background

Escherichia coli O157:H7 is the most common serovar of enterohemorrhagic E. coli associated with serious human disease outbreaks. Cattle are the main reservoir with E. coli O157:H7 inducing hemorrhagic enteritis in persistent shedding beef cattle, however little is known about how this pathogen affects cattle health. Jejunal Hemorrhage Syndrome (JHS) has unclear etiology but the pathology is similar to that described for E. coli O157:H7 challenged beef cattle suggestive that E. coli O157:H7 could be involved. There are no effective treatments for JHS however new approaches to managing pathogen issues in livestock using prebiotics and probiotics are gaining support. The first objective of the current study was to characterize pathogen colonization in hemorrhaged jejunum of dairy cattle during natural JHS outbreaks. The second objective was to confirm the association of mycotoxigenic fungi in feeds with the development of JHS and also to identify the presence of potential mycotoxins. The third objective was to determine the impact of a prebiotic, Celmanax?, or probiotic, Dairyman's Choice? paste, on the cytotoxicity associated with feed extracts in vitro. The fourth objective was to determine the impact of a prebiotic or a probiotic on E. coli O157:H7 colonization of mucosal explants and a bovine colonic cell line in vitro. The final objective was to determine if prebiotic and probiotic feed additives could modify the symptoms that preceded JHS losses and the development of new JHS cases.

Findings

Dairy cattle developed JHS after consuming feed containing several types of mycotoxigenic fungi including Fusarium culmorum, F. poae, F. verticillioides, F. sporotrichioides, Aspergillus flavus, Penicillium roqueforti, P. crustosum, P. paneum and P. citrinum. Mixtures of Shiga toxin - producing Escherichia coli (STEC) colonized the mucosa in the hemorrhaged tissues of the cattle and no other pathogen was identified. The STECs expressed Stx1 and Stx2, but more significantly, Stxs were also present in the blood clot blocking the jejunum. Mycotoxin analysis of the corn crop confirmed the presence of fumonisin, NIV, ZEAR, DON, 15-ADON, 3-ADON, NEO, DAS, HT-2 and T-2. Feed extracts were toxic to enterocytes and 0.1% Celmanax? removed the cytotoxicity in vitro. There was no effect of Dairyman's Choice? paste on feed-extract activity in vitro. Fumonisin, T-2, ZEAR and DON were toxic to bovine cells and 0.1% Celmanax? removed the cytotoxicity in vitro. Celmanax? also directly decreased E. coli O157:H7 colonization of mucosal explants and a colonic cell line in a dose-dependent manner. There was no effect of Dairyman's Choice? paste on E. coli O157:H7 colonization in vitro. The inclusion of the prebiotic and probiotic in the feed was associated with a decline in disease.

Conclusion

The current study confirmed an association between mycotoxigenic fungi in the feed and the development of JHS in cattle. This association was further expanded to include mycotoxins in the feed and mixtures of STECs colonizing the severely hemorrhaged tissues. Future studies should examine the extent of involvement of the different STEC in the infection process. The prebiotic, Celmanax?, acted as an anti-adhesive for STEC colonization and a mycotoxin binder in vitro. Future studies should determine the extent of involvement of the prebiotic in altering disease.     

On the systematic position of the lichen genus Heppia

The systematic position of the lichen genus Heppia in the order Lichinales was investigated. 18S rDNA sequence data were analyzed using a Bayesian approach to infer phylogeny using Markov chain Monte Carlo methods. The Lichinales are divided at family level into the sister groups Lichinaceae and Peltulaceae. The genus Heppia forms a highly supported clade in the family Lichinaceae. It is shown that the genus Heppia is morphologically well circumscribed within the Lichinaceae. As a nomenclatural consequence, the family name Heppiaceae is placed into synonymy under the older name Lichinaceae.     

Study of the effect of the gene ERECTA2 on the development of Arabidopsis thaliana shoot

The role of the gene ER2 in plant development has been studied by the analysis of the erecta2 (er2) mutant of Arabidopsis thaliana (L.) Heynh. It was shown that the mutation er2 provides pleiotropic effect on the development of all aboveground organs. It induces shortening and thickening of the stem, leaves and all flower organs, though it does not change the sensitivity to gibberellin. Changes in the morphology of the shoot organs are due to the changes in cell polarity. The cells get wider and shorter compared to the wild type. It was found that the gene ER2 is located in the lower arm of the chromosome 1. It complementarily interacts with the gene ER that plays an important role in the control of intercellular interactions.     

Distribution of Bacillus thuringiensis in the complex of spore-forming bacteria of the genus Bacillus Cohn in the soils of the nut-fruit forests of southern Kyrgyzstan

Three-year-long investigation of the microflora in the soil of nut-fruit forests in the south of Kyrgyzstan showed a wide distribution of spore-forming bacteria Bacillus subtilis, B. cereus, B. idosus, and B. megaterium. In the complex of these bacteria, crystal-forming bacteria B. thuringiensis are abundant. The occurrence of B. thuringiensis in mountain-forest black-brown soils reaches 80% of soil samples. Dominating subspecies are tohokuensis (H17), israelensis (H14), and toguchini (H31). Abundance of B. thuringiensis was insignificant and accounted for only 1% of spore-forming bacteria. The abundance B. thuringiensis in oozy biocenoses on the shores of water bodies within the Sary-Chelek Biosphere Reserve reaches 12.6–18.0% of soil-forming bacteria. Thus, it is possible to assume that B. thuringiensis not only are conserved in soils but also can reproduce.     

Distribution and some features of biology of representatives of the genus Lycodes in the western part of the Bering Sea in the summer period

Based on materials of bottom inventory trawl survey performed in summer 2008 in the western part of the Bering Sea, we show that representatives of the genus Lycodes in the summer period occur almost throughout the study water area of the sea from the sublittoral to the drop-off. The pattern of distribution and abundance of particular species depend on the depth and specific features of the hydrological regime of the given area. The most numerous species??Lycodes brevipes and L. palearis??are found in warm intermediate and in cold demersal water masses, are distributed over a vast stretch, and there form considerable concentrations. Deep-water species??L. beringi and L. concolor??are more stenothermal, occur along the narrow band of the continental slope, and are considerably inferior to stretch species in numbers. Of shallow species dwelling at depths smaller than 100 m, only L. raridens has high numbers and occurs over a considerable area in the northern part of the study area, the remaining species (L. mucosus, L. polaris, and L. turneri) are caught in small amounts at local sites. The largest sizes are in L. raridens and L. concolor, their maximum length in catches is more than 70 cm, the former species reaches maximum length in the seventh year of life, and the latter reaches maximum length in the ninth year. The smallest and slowest-growing among the studied fish is L. brevipes: its maximum length in catches does not exceed 39 cm and maximum age is 7 years.     

Analysis of spermiogenesis like a tool in the study of the triatomines of the Brasiliensis subcomplex

The specific identification and systematic of triatomines have been based fundamentally on morphological observations. These organisms are classified into complexes and specific subcomplexes, principally for morphological parameters and geographical disposition. The use of cytogenetic analyzes has been represented as a tool in systematic and taxonomy of triatomines. Thus, the present work, through the analysis of spermiogenesis, aims to characterize this stage of spermatogenesis in triatomines little studied, and especially to compare it among the species Triatoma lenti and T. sherlocki, to assist in the diagnosis of differentiation of these insects. The presence of the heteropyknotic corpuscle is shown as a diagnostic tool to differentiate T. sherlocki and T. lenti, since it is absent in T. lenti. The analysis of the spermiogenesis in T. sherlocki also allowed us to address morphological differences between elongating cells, which were relatively smaller and more filamentous when compared to T lenti. Furthermore, the flagellum was observed in all stages of cell differentiation and elongation. This structure, which helps in the locomotion of the sperm, is hardly observed in cytogenetic analysis, especially throughout spermiogenesis. Thus, although other comparative approaches should be taken, this paper allowed emphasizing the analysis of spermiogenesis as an important cytotaxonomic tool that assists in the differentiation of morphologically related species, such as T. lenti and T. sherlocki.     

A New Interpretation of the Dynamic Changes of the Potassium Conductance in the Squid Giant Axon

The solutions, n(t), of the differential equation dn/dt = α (1 - n) n (4 - 6n + 4n² - n³) - βn² (4 - 6n + 4n² - n³) in which α and β are instantaneous functions of membrane potential, are shown to fit with good accuracy the time courses of the rise of potassium conductance during depolarizing steps in clamp potential, found experimentally by Hodgkin and Huxley and by Cole and Moore. The equation is derived by analysing the dynamic behaviour of a system consisting of a square array of interacting pores. The possible role of Ca⁺⁺ ions in this system is discussed.     

The brachiopod family Linoproductidae stehli from the lower Moscovian of the Middle Carboniferous of the Moscow Region

The phylogeny and taxonomy of the brachiopod family Linoproductidae are revised. The change in the distributional pattern of spines and distinctive structure of the median lobe of the cardinal process are shown to be the main apomorphies in the family evolution. A new subfamily, Linispininae, and the included new genera, Linispinella and Linispinus, are described. In the nominotypical subfamily Linoproductinae, a new genus Linoproductoides and two new species included in this genus are described from the Vereiskian deposits of the Moscow Region. The new species Linispinus riparius (Trautschold), L. longus sp. nov., and L. staricensis (Ivanov) are described from the Kashirskian deposits. Another new species is tentatively described as “Linoproductus” kabanovi.     

Stereochemical aspects of the metabolism of the isomeric methylcyclohexanols and methylcyclohexanones

1. The seven isomeric optically inactive forms of methylcyclohexanol (i.e. 1-, and cis- and trans-2-, -3- and -4-) are excreted by rabbits mainly as glucuronides of the thermodynamically more stable forms of the alcohols. The eighth isomer, cyclohexylmethanol, however, undergoes aromatization in vivo, giving rise to benzoic acid and hippuric acid. The (±)-2-, (±-3- and 4-methylcyclohexanones are reduced in the rabbit and excreted mainly as the glucuronides of the thermodynamically more stable forms of the corresponding methylcyclohexanols. 2. Racemic cis- and trans-2-methylcyclohexanol and 2-methylcyclohexanone are all excreted as conjugated trans-2-methylcyclohexanol. However, when the (±)-cis-alcohol or the (±)-ketone is fed, (+)-trans-2-methylcyclohexanol is excreted, whereas when the (±)-trans-alcohol is fed it is excreted as the (±)-trans-alcohol. 3. Racemic cis- and trans-3-methylcyclohexanol and 3-methylcyclohexanone are all excreted as conjugated racemic cis-3-methylcyclohexanol. cis- and trans-4-Methylcyclohexanol and 4-methylcyclohexanone are all excreted as conjugated trans-4-methylcyclohexanol. 4. The metabolic differences between the various methylcyclohexanols are explicable in terms of their conformations and of Vennesland's (1958) hypothesis of the role of NADH in dehydrogenation reactions.     

Analysis of the Bacillus subtilis recO gene: RecO forms part of the RecFLOR function

The deduced protein product of the Bacillus subtilis gene yqfI, which is 255 residues long, shares homology (25% identity) with the Escherichia coli RecO protein. A null allele of yqfI, when present in an otherwise Rec⁺ B. subtilis strain, causes cells to become highly sensitive to DNA-damaging agents, and plasmid transformation (intramolecular recombination) is reduced by 25-fold while chromosomal transformation (intermolecular recombination) is only moderately affected (2.5-fold reduction). Therefore, the yqfI gene was renamed recO and its null allele is referred to as recO1. The recO1 mutation was introduced into recombination-deficient strains representative of the epistatic groups α (recF, recR and recL strains), β (addA5 addB72), γ (recH342) and ? (recU40). The recO mutation did not affect the sensitivity of recF, recR or recL cells to DNA-damaging agents, increased the sensitivity of recU and addAB cells and abolished the DNA repair capacity of recH cells. The recO mutation did not affect intermolecular recombination in recF, recL, recH or recU cells, but reduced (by about 9-fold) the incidence of intermolecular recombination in addAB cells. The recO mutation did not affect intramolecular recombination in the addAB, recU, recF or recL cells, but reduced it by about 75-fold in recH cells. The defects caused by the recO1 mutation can be partially suppressed by a common suppressor of the recF, recL and recR phenotypes. We therefore assigned recO to epistatic group α and predict that the RecO protein acts at the same stage of recombination as the RecF, RecL and RecR proteins, in a RecFLOR complex.     

On the occurrence of tuliposides in the liliiflorae

Approximately 200 samples of liliiflorous plants were investigated for the presence of tuliposides. Appreciable amounts of tuliposide A were detected in all species of Erythronium, Tulipa, Gagea, Bomarea and Alstroemeria. Large amounts of tuliposide B seem to be restricted to Erythronium and Tulipa. The occurrence of identical post-inhibitins in Tulipa and allied taxa and in Alstroemeria and allied taxa is interpreted as indicating a close relationship between Lilioideae and Alstroemeriaceae. At the same time the allergenic potentialities of all taxa of Alstroemeria are stressed.     

A modifier of the Bg element of the Bg-rbg transposable element system of maize

A modifier of the Bg autonomous element of the Bg-rbg system of transposable elements has been found in the genotype of the inbred maize line 346. In the presence of this modifier (designated Mbg), the frequency of reversion of mutable allele o2-lf in combination with the Bg-lf element increases by 7–24 times. An increase in the Mbg dosage by three times increases the o2-lf reversion frequency by a factor of about two. The joint presence of Mbg and Bg-lf in the same genotype before meiosis is necessary for the expression of the Mbg modifying effect. The possible nature and mechanism of action of the novel modifier are discussed.     

Pelagic cephalopods of the central Mediterranean Sea determined by the analysis of the stomach content of large fish predators

The pelagic cephalopod fauna of the central Mediterranean Sea was investigated through stomach content analyses of large fish predators. A total of 124 Xiphias gladius, 22 Thunnus thynnus, 100 Thunnus alalunga, and 25 Tetrapturus belone were analyzed. Overall, 3,096 cephalopods belonging to 23 species and 16 families were identified. The cephalopod fauna in the study area is dominated by Sepiolidae, Ommastrephidae, and Onychoteuthidae. The sepiolid Heteroteuthis dispar was the most abundant species (n?=?1,402) while the ommastrephid Todarodes sagittatus showed the highest biomass. They can be considered key-species in the pelagic food web of the study area. The neutrally buoyant Histioteuthis bonnellii, H. reversa, and Chiroteuthis veranyi seem to characterize the deeper water layers. Given the difficulty in sampling pelagic cephalopods, the presence of cephalopod beaks in the stomach of predators represents a fundamental tool to assess the biodiversity and the ecological importance of these taxa in the marine ecosystem.     

Reassessment of the Morphology and Taxonomic Status of the Earliest Herpetotheriid Marsupials of Europe

The earliest Eocene locality of Dormaal (Belgium) has provided the oldest Cenozoic herpetotheriid marsupials of Europe. No herpetotheriid has ever been reported earlier than the Eocene in Europe, except for a questionable single upper molar from the Upper Cretaceous of the Belgian/Dutch border. The systematics of the herpetotheriids of Dormaal was formerly based on only a dozen dental specimens, which were assigned, after several revisions, to two species Peratherium constans and Amphiperatherium brabantense. Most importantly, these two species were considered at the root of most of the hepetotheriid lineages of the European Paleogene. Here we report a large sample of about 400 new dental remains that allow a better definition of both species as well as a testing of their systematic status. The evidence of significant morphological variability leads us to reconsider the diagnosis of Peratherium constans and to question the validity of Amphiperatherium brabantense. This study highlights that the primitive species Peratherium constans and Amphiperatherium brabantense are hardly distinguishable from each other, and therefore conclude that Peratherium constans was the only marsupial present at Dormaal. The important morphological variation exhibited by this herpetotheriid is similar to the variability observed in the type-species Peratherium elegans and in other fossil and extant metatherians. Consequently, our results suggest that several Amphiperatherium species from the Eocene could represent variants of the genus Peratherium. The question of the Amphiperatherium presence in Europe is therefore raised and a thorough discriminate analysis of both genera should be conducted in later works.     

Dioptrics of the facet lenses in the dorsal rim area of the cricket Gryllus bimaculatus

1. The optics of the corneal facet lenses from the dorsal rim area (DRA) and from the dorso-lateral areas (DA) of the compound eye of the cricket Gryllus bimaculatus were studied.
2. The DRA of the cricket eye contains quite normally shaped facet lenses. The diameter of the facet lens in the DA is 2-fold larger compared to that in the DRA. The radius of curvature of the front surface is distinctly less in the DA facet lenses, as the surface of the facet lenses in the DRA are virtually flat.
3. The averaged axial refractive index of the facet lenses of Gryllus bimaculatus, measured by interference microscopy, was 1.496 ± 0.008 (n = 42) in the DRA and 1.469 ± 0.004 (n = 39) in the DA. The geometrical thickness of the lenses was calculated to be 77 ± 3 μm (n = 42) in the DRA and 56 ± 1 μm (n = 39) in the DA.
4. Analysis of the diffraction pattern obtained with a point light source revealed distinct focusing properties of both the DRA and the DA facet lenses; striking Airy-like diffraction patterns were obtained in both cases.
5. Focal distances measured directly at the backfocal plane were 40 ± 8 μm (n = 84) in the DRA of all the animals studied, and 60–90 μm (n = 62) in DA depending on the animal. Analysis of the diffraction of the point light source yielded very similar focal distances: 40 ± 5 μm (n = 10) in DRA and 81 ± 8 μm (n = 11) in DA. In the DRA, focal distance of the facet lenses was smaller than the cone length, 58 ± 3 μm (n = 9) while in the DA the focal distance matched the effective cone length, 71 ± 5 μm (n = 16).

     

A study of the mechanism of the antiarrhythmic action of Allapinin

Allapinin (lappaconitine hydrobromide) is a drug used for the treatment of cardiac rhythm disturbances; its properties are characteristic of class IC antiarrhythmics. The mechanism of its electrophysiological action involves the blockade of Na⁺ channels with a subsequent decrease of depolarization rate leading to a slowing of impulse propagation and a decrease of excitability in the conductive system of the heart. Factors underlying the side effects of Allapinin (tachycardia, arterial hypertension, impaired coordination, etc.) are currently unknown, and therefore a study of the molecular mechanisms of its action seems relevant. The target genes of the drug were identified in rats with induced aconitine arrhythmia using the commercially available Rat Neuroscience Ion Channels & Transporters RT² Profiler? PCR Array kit (SA Biosciences). A comparison of expression levels of 84 genes in rats treated with Allapinin, after the induction of arrhythmia by aconitine (experiment) and in physiological saline-treated arrhythmic rats (control), revealed 18 mRNAs which were up- or downregulated twofold or more in the experiment relative to the control. Allapinin was shown to stimulate the expression of genes coding for various types of K⁺ channels (kcna6, kcnj1, kcnj4, kcnq2, and kcnq4), Ca²⁺ channel (cacna1g), and vesicular acetylcholine transporter (slc18a3). A decrease in mRNA levels was detected for genes coding for K⁺ channels (kcne1, kcns1), a Na⁺ channel (scn8a), and membrane transporter genes (atp4a, slc6a9). Our data shows that Allapinin administered to animals with aconitine arrhythmia modulates the expression of genes accounting for ion current conductances involved in the formation of various phases of action potential (I _Na , I _to , I _Ks , I _K1 , I _CaT ). The effect of the drug on the levels of mRNAs coding for acetylcholine and glycine transporters suggests the involvement of these neuromediators in the mechanisms underlying the antiarrhythmic effect of Allapinin.     

Mitotic Recombination in the Heterochromatin of the Sex Chromosomes of DROSOPHILA MELANOGASTER

The frequency of spontaneous and X-ray-induced mitotic recombination involving the Y chromosome has been studied in individuals with a marked Y chromosome arm and different XY compound chromosomes. The genotypes used include X chromosomes with different amounts of X heterochromatin and either or both arms of the Y chromosome attached to either side of the centromere. Individuals with two Y chromosomes have also been studied. The results show that the bulk of mitotic recombination takes place between homologous regions.