Investigation of Paradiplozoon homoion (Monogenea, Diplozoidae) life cycle under experimental conditions

Diplozoids (Diplozoidae, Monogenea) are fish ectoparasites with a direct life cycle without intermediate hosts. Their free swimming larva, the oncomiracidium, hatches from eggs, invades a fish host and metamorphoses into a post-oncomiracidial larval stage, the diporpa. Later, two diporpae fuse and live as a pair in cross-copulation during their adult life. An experimental study was designed to investigate the life cycle of Paradiplozoon homoion (Monogenea, Diplozoidae) parasitizing their common fish hosts, gudgeon (Gobio gobio). A total of 35 gudgeon parasitized by diplozoids were collected from their natural environment of the Vlára River, Czech Republic, and kept together in tanks with 41 non-parasitized gudgeons reared in a laboratory environment. In total, 100 adult specimens of P. homoion were collected from the Vlára River gudgeon and a new parasite generation was expected to be observed on fish reared in the laboratory environment. Eight days after the first diplozoid eggs appeared on fish gills, the presence of diporpae with one or two pairs of clamps was noted. The appearance of the first juveniles was recorded at the same time as diporpae. Development of P. homoion from egg to sexually mature adult stage took 33 days at a constant temperature of 20 degrees C. The development of eggs in adults of the second generation was observed 2 days after the first observation of these adults. The behavior of oncomiracidia was also studied and this free swimming stage of diplozoids survived for 22 h in the absence of a host. When host fish were experimentally infected by oncomiracidia, diporpae were found attached to the fish gill apparatus within 2 h of infection.     

Mycobacterium tuberculosis CwsA Interacts with CrgA and Wag31, and the CrgA-CwsA Complex Is Involved in Peptidoglycan Synthesis and Cell Shape Determination

Bacterial cell division and cell wall synthesis are highly coordinated processes involving multiple proteins. Here, we show that Rv0008c, a novel small membrane protein from Mycobacterium tuberculosis, localizes to the poles and on membranes and shows an overall punctate localization throughout the cell. Furthermore, Rv0008c interacts with two proteins, CrgA and Wag31, implicated in peptidoglycan (PG) synthesis in mycobacteria. Deletion of the Rv0008c homolog in M. smegmatis, MSMEG_0023, caused bulged cell poles, formation of rounded cells, and defects in polar localization of Wag31 and cell wall synthesis, with cell wall synthesis measured by the incorporation of the [¹⁴C]N-acetylglucosamine cell wall precursor. The M. smegmatis MSMEG_0023 crgA double mutant strain showed severe defects in growth, viability, cell wall synthesis, cell shape, and the localization of the FtsZ, FtsI, and Wag31 proteins. The double mutant strain also exhibited increased autolytic activity in the presence of detergents. Because CrgA and Wag31 proteins interact with FtsI individually, we believe that regulated cell wall synthesis and cell shape maintenance require the concerted actions of the CrgA, Rv0008c, FtsI, and Wag31 proteins. We propose that, together, CrgA and Rv0008c, renamed CwsA for cell wall synthesis and cell shape protein A, play crucial roles in septal and polar PG synthesis and help coordinate these processes with the FtsZ-ring assembly in mycobacteria.     

Three new species of picobiine mites (Acari: Syringophilidae) parasitising African flycatchers (Aves: Muscicapidae)

Three new species of quill mites of the subfamily Picobiinae Johnston & Kethley, 1973 (Acari: Syringophilidae) are described from African flycatchers (Passeriformes: Muscicapidae): Picobia cichladusa n. sp. on Cichladusa arquata Peters and P. myrmecocichla n. sp. on Myrmecocichla arnotti (Tristram), both from Tanzania, and P. echo n. sp. on Cossypha heuglini Hartlaub from the Democratic Republic of the Congo.     

Molecular and functional interactions between Escherichia coli nucleoside-diphosphate kinase and the uracil-DNA glycosylase Ung

Escherichia coli nucleoside-diphosphate kinase (Ndk) catalyzes nucleoside triphosphate synthesis and maintains intracellular triphosphate pools. Mutants of E. coli lacking Ndk exhibit normal growth rates but show a mutator phenotype that cannot be entirely attributed to the absence of Ndk catalytic activity or to an imbalance in cellular triphosphates. It has been suggested previously that Ndk, similar to its human counterparts, possesses nuclease and DNA repair activities, including the excision of uracil from DNA, an activity normally associated with the Ung and Mug uracil-DNA glycosylases (UDGs) in E. coli. Here we have demonstrated that recombinant Ndk purified from wild-type E. coli contains significant UDG activity that is not intrinsic, but rather, is a consequence of a direct physical and functional interaction between Ung and Ndk, although a residual amount of intrinsic UDG activity exists as well. Co-purification of Ung and Ndk through multicolumn low pressure and nickel-nitrilotriacetic acid affinity chromatography suggests that the interaction occurs in a cellular context, as was also suggested by co-immunoprecipitation of endogenous Ung and Ndk from cellular extracts. Glutathione S-transferase pulldown and far Western analyses demonstrate that the interaction also occurs at the level of purified protein, suggesting that it is specific and direct. Moreover, significant augmentation of Ung catalytic activity by Ndk was observed, suggesting that the interaction between the two enzymes is functionally relevant. These findings represent the first example of Ung interacting with another E. coli protein and also lend support to the recently discovered role of nucleoside-diphosphate kinases as regulatory components of multiprotein complexes.     

Extension of the Nef reaction to C-glycosylnitromethanes

Acid-catalysed methanolysis of 3,4,5,6-tetra-O-acetyl-1,2-dideoxy-l-arabino-hex-1-enitol proceeds via a cascade set of consecutive reactions resulting in its regiospecific conversion to a mixture of alpha- and beta-C-L-arabinofuranosylmethanal dimethyl acetals and a mixed internal methyl acetal. Structures of the final products of the overall process provide unique evidence that a kinetically controlled, five-membered-ring closure precedes a six-membered-ring closure in reversible systems capable of giving both five-membered and six-membered all-sp3-atom rings. Determination of the reaction intermediate enabled extension of the Nef reaction to C-glycosylnitromethanes. Protonated aci-nitro forms of C-glycosylnitromethanes that are resistant to the Nef reaction in aqueous acidic media undergo a modified Nef reaction in acidified methanol, and the corresponding C-glycosylmethanal dimethyl acetals with alpha-L-arabinopyranosyl, beta-D-glucopyranosyl, beta-D-galactopyranosyl, beta-D-mannopyranosyl and beta-L-rhamnopyranosyl configurations were obtained in moderate yields.     

Distinct DNA repair pathways involving RecA and nonhomologous end joining in Mycobacterium smegmatis

Mycobacterium smegmatis was used to study the relationship between DNA repair processes involving RecA and nonhomologous end joining (NHEJ). The effect of gene deletions in recA and/or in two genes involved in NHEJ (ku and ligD) was tested on the ability of bacteria to join breaks in plasmids transformed into them and in their response to chemicals that damage DNA. The results provide in vivo evidence that only NHEJ is required for the repair of noncompatible DNA ends. By contrast, the response of mycobacteria to mitomycin C preferentially involved a RecA-dependent pathway.     

Chronic thyroiditis--current issue in the cytological diagnostics of the thyroid gland

INTRODUCTION: Lowered and non-homogenous echogenicity in patients with chronic thyroiditis (CT) may cause problems in revealing focal lesions in ultrasound scans. Moreover, frequent anisocytosis of thyroid follicular cells and of oncocytes may falsely suggest neoplastic growth. The aim of the study was to evaluate the frequency of CT diagnosed in patients subjected to fine-needle aspiration biopsy (FNAB) of the thyroid in years 1994-2005, as well as to assess the cancer frequency in the operated patients with CT. MATERIAL AND METHODS: As much as 23 173 cytological reports and corresponding outcomes were analyzed and in patients treated surgically verified against postoperative histopathological examinations. Moreover, the analysis of cytological smears in CT with distinguishing its types (lymphocytic, epithelial-hyperplastic, colloidal, oxyphillic) was performed in 50 patients; the changes between subsequent FNABs in the picture of the smears were also assessed. RESULTS: The frequency of diagnosed CT had been increasing in the evaluated time span from 2.6% to 9.7% (p < 0.0001). There were 11 cases of papillary carcinoma found coexisting with CT. The analysis of cytological types of CT showed that the lymphocytic type prevailed over the others (lymphocytic - 43%, colloidal--21%, epithelial-hyperplastic--20%, oxyphilic--16%, p < 0.001). The evolution in time of the cytological picture was observed. CONCLUSION: The increase in the frequency of CT observed in smears obtained from the thyroid gland and the reports on the coexistence of CT with papillary carcinoma suggest the necessity of prudent diagnostics and follow-up of patients with CT.     

Role of pro-oxidant properties of flavonoids in the induction of detoxifying enzymes gene expression

Flavonoids are one of the most important components of human daily diet. In recent years flavonoids have became the subject of extensive investigations mostly due to their heath-promoting properties. Beneficial health effects of flavonoids are mainly ascribed to their antioxidant activity. However, there is increasing evidence of the positive role of pro-oxidant properties of flavonoids, considered previously as highly unfavorable, through the induction of detoxifying enzymes gene expression. The article discusses recent reports on the EpRE-mediated induction of NQO1 (NAD(P)H: quinone oxidoreductase) gene expression by the flavonoids (flavonols, flavones and flavan-3-oles) and the role of pro-oxidant properties of the flavonoids in the mechanism of this induction.