Association of multiple-antibiotic-resistance profiles with point and nonpoint sources of Escherichia coli in Apalachicola Bay.

A total of 765 Escherichia coli isolates from point and nonpoint sources were collected from the Apalachicola National Estuarine Research Reserve, and their multiple-antibiotic-resistance (MAR) profiles were determined with 10 antibiotics. E. coli isolates from point sources showed significantly greater resistance (P < 0.05) to antibiotics and higher MAR indices than isolates from nonpoint sources. Specifically, 65 different resistance patterns were observed among point source isolates, compared to 32 among nonpoint source isolates. Examples of this contrast in MAR profiles included percentages of isolates with resistance to chlortetracycline-sulfathiazole of 33.7% and to chlortetracycline-penicillin G-sulfathiazole of 14.5% for point source isolates versus 15.4 and 1.7%, respectively, for nonpoint source isolates. MAR profile homology, based on coefficient similarity, showed that isolates from point sources were markedly more diverse than isolates from nonpoint sources. Seven clusters were observed among point source isolates, with a coefficient value of approximately 1.8. In contrast, only four clusters were observed among nonpoint source isolates. Covariance matrices of data displayed six very distinct foci representing nonpoint source E. coli isolates. Importantly, E. coli isolates obtained directly from human and animal feces also clustered among point and nonpoint sources, respectively. We conclude that E. coli MAR profiles were associated with point and nonpoint sources of pollution within Apalachicola Bay and that this method may be useful in facilitating management of other estuaries.     

On the distributive pattern of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) in the medulla oblongata of the golden hamster (Mesocricetus auratus). A study on the topographical and functional linkages of the two enzymes

Histochemical study on the distributive patterns of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), amongst the constituents of the medulla oblongata of golden hamster (Mesocricetus auratus), viewed through the angle of the possible topographical and functional linkage of the two enzymes, have provided identical set-ups of AChE and BChE in many of the nuclei, fibers and tracts. In the case of AChE in many instances the results further point out that there is a balance of the enzymatic activity between the nuclei and the associated processes. On the other hand, in relation to BChE activity, the nuclei and their processes do not seem to be linked through such a histochemical factor. A detailed discussion on the significance of AChE relationship between the neurons and their processes from the functional point of view, against the data available in the literature, has been incorporated in the present study. Histoenzymologically, the ranges of the activities of AChE and BChE amongst the neurons and their processes are so closely related that such components are mirror images of each other in histochemical patterns. Naturally, such results have led to a detailed discussion in the contribution culminating in a proposition that AChE and BChE (amongst the locales studied) seems to be intimately linked in the neuro-physiological functioning undergoing in the regions of the medulla oblongata of golden hamster.     

A comparative study of the ultrastructure of resting and active cambium of Salix fragilis,L.

Summary Cells of the resting cambium contain vesiculate smooth endoplasmic reticulum, free ribosomes, oil droplets, and protein bodies. There are comparatively few vacuoles, and these are small. The nucleus is fairly central within the cell and is surrounded by a cluster of plastids and mitochondria. Active cambial cells and young differentiating xylem elements are highly vacuolate, contain rough endoplasmic reticulum and polyribosomes, the Golgi apparatus is active in the production of vesicles, and the distribution of organelles is a function of the vacuolation of the cell.It is suggested that the lipid droplets and protein bodies are storage materials which are required during the first stages of differentiation at the beginning of the growing period.     

Two new species of Cephalobellus Cobb, 1920 (Thelastomatidae: Nematoda) from coleopteran larvae from India

Summary Two new species of Cephalobellus, C. annulobellus and C. spicatus, collected from unidentified coleopteran larvae in Aligarh, India, are described and figured. Both species have characteristic closely set annules in the cervical region of their females and five pairs of caudal papillae and lateral alae in the males. C. annulobellus possesses a labial disc, has a smaller body and different shape and arrangement of caudal papillae than in C. spicatus. A key to the species of Cephalobellus is given. ac]19830610     

Light-adapted charge-separated state of photosystem II: structural and functional dynamics of the closed reaction center

Photosystem II (PSII) uses solar energy to oxidize water and delivers electrons for life on Earth. The photochemical reaction center of PSII is known to possess two stationary states. In the open state (PSII_O), the absorption of a single photon triggers electron-transfer steps, which convert PSII into the charge-separated closed state (PSII_C). Here, by using steady-state and time-resolved spectroscopic techniques on Spinacia oleracea and Thermosynechococcus vulcanus preparations, we show that additional illumination gradually transforms PSII_C into a light-adapted charge-separated state (PSII_L). The PSII_C-to-PSII_L transition, observed at all temperatures between 80 and 308 K, is responsible for a large part of the variable chlorophyll-a fluorescence (F_v) and is associated with subtle, dark-reversible reorganizations in the core complexes, protein conformational changes at noncryogenic temperatures, and marked variations in the rates of photochemical and photophysical reactions. The build-up of PSII_L requires a series of light-induced events generating rapidly recombining primary radical pairs, spaced by sufficient waiting times between these events—pointing to the roles of local electric-field transients and dielectric relaxation processes. We show that the maximum fluorescence level, F_m, is associated with PSII_L rather than with PSII_C, and thus the F_v/F_m parameter cannot be equated with the quantum efficiency of PSII photochemistry. Our findings resolve the controversies and explain the peculiar features of chlorophyll-a fluorescence kinetics, a tool to monitor the functional activity and the structural-functional plasticity of PSII in different wild-types and mutant organisms and under stress conditions.

The closed-state of photosystem II possesses a hitherto unrecognized structural and functional plasticity and upon illumination assumes a light-adapted charge-separated state.     

Enhanced shoot organogenesis in Cassia angustifolia Vahl. — a difficult-to-root drought resistant medicinal shrub

In vitro regeneration was achieved through callus culture derived from cotyledon explants of Cassia angustifolia Vahl. on MS (Murashige and Skoog, 1962) medium. Calli were induced from cotyledon explants excised from aseptic 14?days old seedlings on MS medium containing 2,4-D (2,4-dichlorophenoxy acetic acid) and 2,4,5-T (2,4,5-trichlorophenoxy acetic acid) at different concentrations with 3% sucrose and 0.8% agar. Optimal growth of callus was obtained at 5.0???M 2,4-D, which was proved to be the best for shoot regeneration when sub cultured onto MS medium supplemented with cytokinins either alone or in combination with an auxin. Maximum number of shoots (23.2?±?1.4) were produced at 5.0???M 6-benzylaminopurine (BA) and 0.4???M ??-naphthalene acetic acid (NAA). Regenerated shoots produced prominent roots when transferred to half strength MS medium supplemented with 1.0???M indole-3-butyric acid (IBA) and 5.0???M phloroglucinol (PG). Rooted plantlets thus developed were hardened and successfully established in the soil. This protocol yielded an average of 23 plants per cotyledon explant over a period of 4?months.     

Applying unconventional secretion of the endochitinase Cts1 to export heterologous proteins in Ustilago maydis

The demand on the biotechnological production of proteins for pharmaceutical, medical and industrial applications is steadily growing. For the production of challenging proteins, we aim to establish a novel expression platform in the well characterized eukaryotic microorganism Ustilago maydis. In filaments of this fungus, secretion of the endochitinase Cts1 depends on mRNA transport along microtubules, which is mediated by the key RNA-binding protein Rrm4. Here, we report two important findings: (i) Cts1 secretion occurs via a novel unconventional route and (ii) this secretory mechanism can be exploited for the export of active heterologous proteins. Initially, we used β-glucuronidase (Gus) as a reporter for unconventional secretion. This bacterial enzyme is inactivated by N-glycosylation during its passage through the conventional eukaryotic secretory pathway. By contrast, in our system Gus was exported in its active form by fusion to Cts1 confirming its secretion by an unconventional route. As a proof-of-principle for economically important biopharmaceuticals we expressed an active single-chain antibody. Importantly, the novel protein export pathway circumvents N-glycosylation which is advantageous in many applications, e.g., to avoid undesired immune reactions in humans. Thus, the unconventional Cts1 secretion machinery has a high potential for the production of biotechnologically relevant proteins.     

Geographical variation in antibiotic resistance profiles of Escherichia coli isolated from swine, poultry, beef and dairy cattle farm water retention ponds in Florida

AIMS: The aim of this study was to assess geographical variation in multiple antibiotic resistance (MAR) profiles of livestock Escherichia coli as well as to evaluate the ability of MAR profiles to differentiate sources of faecal pollution. METHODS AND RESULTS: More than 2000 E. coli isolates were collected from water retention ponds and manure of swine, poultry, beef and dairy farms in south, central and north Florida, and analysed for MAR using nine antibiotics. There were significant differences in antibiotic resistance of E. coli by season and livestock type for more than one antibiotic, but regional differences were significant only for ampicillin. Over the three regions, discriminant analysis using MAR profiles correctly classified 27% of swine, 49% of poultry, 56% of beef and 51% of dairy isolates. CONCLUSIONS: Regional variations in MAR combined with moderate discrimination success suggest that MAR profiles of E. coli may only be marginally successful in identifying sources of faecal pollution. SIGNIFICANCE AND IMPACT OF THE STUDY: This study demonstrates the existence of regional and seasonal differences in MAR profiles as well as the limited ability of MAR profiles to discriminate among livestock sources.