The bacterial flora and their possible association with spoilage in a variety of fresh-water fish: Cyprinus carpio. var. communis

The bacteria from a variety of fresh-water fish, Cyprinus carpio. var. communis, showed the presence of micrococci, Gram positive and Gram negative rods. These have been characterized as far as was possible. Of thirty-eight strains of bacteria used, only six strains were considered as causing spoilage of fish flesh in experiments where flesh was incubated with individual cultures of the bacteria. These six strains had been found on the surface and/or intestine of the fish and support the suggestions that, after death, invasion of flesh by bacteria from the surface and intestine could be the cause of bacterial spoilage of fish.

Quantitative and qualitative studies on the bacterial flora of fresh sardines

Plate counts at R T and 8 C on the skin with muscle and the gut contents of absolutely fresh sardines (Sardinella longiceps) caught off Cochin showed a seasonal variation when sampling was done over a period of 12 months. The counts of the gut contents ran parallel with those of the skin with muscle, but at a higher level of magnitude. Qualitatively, the analysis of 360 strains of bacteria isolated from the skin with muscle and 100 strains from the guts during a year's study revealed a very high preponderance of Gram negative rods, mainly of Achromobacter, Vibrio, and Pseudomonas groups. The percentage of Gram positive organism was very low or nil at times in the ocean fresh sardines.

Investigation on bacterial flora of farmed freshwater prawn (Macrobrachium rosenbergii de Man) in Bangladesh

Total bacterial load in the haemolymph of freshwater prawn Macrobrachium rosenbergii varied from 6.2x10⁴ to 1.9x10⁷ CFU/ml whereas in the hepatopancreas, bacterial load varied from 1.9x10³ to 2.9x10⁵ CFU/g. The total bacterial load in the pond water varied from 2.6x10² to 4.1x10⁵ CFU/ml. The isolated bacterial genera in the haemolymph and the hepatopancreas of prawn were Streptococcus, Acinetobacter, Micrococcus, Aeromonas, Vibrio, Flavobacterium, Staphylococcus and Pseudomonas, whereas the detected bacterial genera in pond water were Micrococcus, Streptococcus, Vibrio, Flavobacterium, Staphylococcus, Pseudomonas and Aeromonas. Among the detected genera, Vibrio and Staphylococcus were found to be dominant genera in the haemolymph of the sampled prawn throughout the study period whereas Staphylococcus and Pseudomonas were dominant in pond water.

Bacterial quality and depuration of the green mussel Perna viridis from natural beds

Green mussel (Perna viridis) and sea water from their natural beds on the coastal areas of Porto Novo were studied between April and August 1996 for their bacterial quality. Water samples from the beds were also analysed for their physico-chemical parameters. The total bacterial count of mussels from natural beds as well as bed waters ranged 10³ organisms per gram of mussel meat suspension and per milliliter of sea water. The faecal coliforms were found to be within the permissible limits. Pathogenic bacteria such as Salmonella spp., Streptococcus spp. and Staphylococcus spp. were absent. The variations in pH, temperature, salinity and dissolved oxygen of the seawater samples were insignificant. The mussels were subjected to depuration by different methods among which chlorination was found to be most effective.

A Comparison of the bacterial flora of surface and sub-surface water of the sea off Ceylon

Under stable conditions of stratification of the sea, evidence of generic differences of the associated bacterial flora of the water masses has been obtained, between surface and sub-surface water. Gram negative rods, especially pseudomonads and achromobacters were more frequent at the surface. The fermentative and oxidase negative flora was more frequent in sub-surface water. The surface water in general had a greater variety of bacterial types while the sub-surface water had a flora with a greater range of biochemical activity. These results are discussed in relation to the hydrological condition of the water masses and the bacterial flora of freshly caught fish.

Wave digital filter model of the entire auditory periphery

A model of the auditory periphery assembled from analog network submodels of all the relevant anatomical structures is described. There is bidirectional coupling between networks representing the outer ear, middle ear and cochlea. A simple voltage source representation of the outer hair cells provides level-dependent basilar membrane curves. The networks are translated into efficient computational modules by means of wave digital filtering. A feedback unit regulates the average firing rate at the output of an inner hair cell module via a simplified modelling of the dynamics of the descending paths to the peripheral ear. This leads to a digital model of the entire auditory periphery with applications to both speech and hearing research.

Bacterial flora associated with diseased fish and their antibiogram

Bacterial flora associated with tail rot/fin rot of Carassius auratus, Xiphophorus helleri and hemorrhagic ulcers of Clarias spp were studied. Sensitivity pattern of 33 isolates comprising Aeromonas spp, Pseudomonas spp and Gram-positive rods from diseased C. auratus, X. helleri and Clarias spp were screened against six broad-spectrum antibiotics viz. ciprofloxacin, chloramphenicol, co-trimoxazole, gentamycin, nitro-furantoin and oxytetracycline. Ciprofloxacin was the most effective in inhibiting bacteria at 0.05-0.10 µg/ml level. About 44% of Pseudomonas spp. was resistant to nitrofurantoin. Resistance to oxytetracycline was seen in 27% of Aeromonas spp Gram-positive rods were comparatively more resistant to antibiotics. The multiple antibiotic resistances were seen in 21% of the bacterial isolates of diseased fish.

Construction and characterization of bacterial artificial chromosome library of black-handed spider monkey (Ateles geoffroyi)

The large-insert genomic DNA library is a critical resource for genome-wide genetic dissection of target species. We constructed a high-redundancy bacterial artificial chromosome (BAC) library of a New World monkey species, the black-handed spider monkey

Construction, characterization and chromosomal mapping of bacterial artificial chromosome (BAC) library of Yunnan snub-nosed monkey (Rhinopithecus bieti)

We constructed a high redundancy bacterial artificial chromosome library of a seriously endangered Old World Monkey, the Yunnan snub-nosed monkey (Rhinopithecus bieti) from China. This library contains a total of 136 320 BAC clones. The average insert size of BAC clones was estimated to be 148 kb. The percentage of small inserts (50-100 kb) is 2.74%, and only 2.67% non-recombinant clones were observed. Assuming a similar genome size with closely related primate species, the Yunnan snub-nosed monkey BAC library has at least six times the genome coverage. By end sequencing of randomly selected BAC clones, we generated 201 sequence tags for the library. A total of 139 end-sequenced BAC clones were mapped onto the chromosomes of Yunnan snub-nosed monkey by fluorescence in-situ hybridization, demonstrating a high degree of synteny conservation between humans and Yunnan snub-nosed monkeys. Blast search against human genome showed a good correlation between the number of hit clones and the size of the chromosomes, an indication of unbiased chromosomal distribution of the BAC library. This library and the mapped BAC clones will serve as a valuable resource in comparative genomics studies and large-scale genome sequencing of nonhuman primates. The DNA sequence data reported in this paper were deposited in GenBank and assigned the accession number CG891489-CG891703.

Bacterial load in pond water and different organs of a Indian major carp Cirrhinus mrigala Ham.

During the study period (August, 1993 to July,l994) the mean bacterial load in surface water was found to vary from 1.39 xl05 (July'94) to 3.llxl07CFU/ml (September'93), while that of botrom water ranged from l.Olxl06 (May'94) to 5.90xl07CFU/ml (October '93). The mean total number of bacterial load in body slime, liver and kidney was found to vary from 0.58xl03 (July'94) to 2.37xl07CFU/g (March'94),from 0.22xl03(July'94)to 9.64xl06 CFU/g (March'94) from O.l5xl03 (July'94) to 9.36xl06 CFU/g (March'94), respectively. Bacterial load in slime was significantly correlated with bacterial load in liver, bacterial load in slime was significantly correlated with bacterial load in kidney and bacterial load in liver was significantly correlated with bacterial load in kidney.

Perspectives on the origin of microfilaments, microtubules, the relevant chaperonin system and cytoskeletal motors - a commentary on the spirochaete origin of flagella

The origin of cytoskeleton and the origin of relevant intracellular transportation system are big problems for understanding the emergence of eukaryotic cells. The present article summarized relevant information of evidences and molecular traces on the origin of actin, tubulin, the chaperonin system for folding them, myosins, kinesins, axonemal dyneins and cytoplasmic dyneins. On this basis the authors proposed a series of works, which should be done in the future, and indicated the ways for reaching the targets. These targets are mainly: 1) the reconstruction of evolutionary path from MreB protein of archaeal ancestor of eukaryotic cells to typical actin; 2) the finding of the MreB or MreB-related proteins in crenarchaea and using them to examine J. A. Lake's hypothesis on the origin of eukaryote from "eocytes" (crenarchaea); 3) the examinations of the existence and distribution of cytoskeleton made of MreB-related protein within coccoid archaea, especially in amoeboid archaeon Thermoplasm acidophilum; 4) using Thermoplasma as a model of archaeal ancestor of eukaryotic cells; 5) the searching for the homolog of ancestral dynein in present-day living archaea. During the writing of this article, Margulis' famous spirochaete hypothesis on the origin of flagella and cilia was unexpectedly involved and analyzed from aspects of tubulins, dyneins and spirochaetes. Actually, spirochaete cannot be reasonably assumed as the ectosymbiotic ancestor of eukaryotic flagella and cilia, since their swing depends upon large amount of bacterial flagella beneath the flexible outer wall, but not depends upon their intracellular tubules and the assumed dyneins. In this case, if they had "evolved" into cilia and lost their bacterial flagella, they would immediately become immobile! In fact, tubulin and dynein-like proteins have not been found in any spirochaete.

New symbiotic hypothesis on the origin of eukaryotic flagella

The origin of eukaryotic flagella has long been a mystery. Here we review the possibility that flagella sprouted evolutionarily from the eukaryotic cell proper seems very unlikely because it is hard to imagine what function and benefit in natural selection the flagella would have provided to the cells when they first emerged as simple buds. Lynn Margulis' 1970 spirochete hypothesis, though popular still, has never been confirmed. Moreover, the absence of tubulin and axonemal dynein in the spirochetes and the incapability of the bacterial and eukaryotic membranes' making a continuum now suggest that the hypothesis is outdated. Tubulin genes were recently identified in a new bacteria division, verrucomicrobia, and microtubules have also been found in one of these species, epixenosomes, the defensive ectosymbionts. On the basis of these data, we propose a new symbiotic hypothesis: that the mid-ancestor of eukaryotic cells obtained epixenosomelike verrucomicrobia as defensive ectosymbionts and the ectosymbionts later became endosymbiotic. They still, however, protruded from the surface of their host to play their role. Later, many genes were lost or incorporated into the host genome. Finally, the genome, the bacterial membrane, and the endosymbiotic vesicle membrane were totally lost, and fingerlike protrusions with microtubules formed. As the cells grew larger, the defensive function of the protrusions eventually weakened and then vanished. Some of the protrusions took on a new role in cell movement, which led them to evolve into flagella. The key step in this process was that the dynein obtained from the host evolved into axonemal dyneins, attaching onto the microtubules and forming motile axonemes. Our hypothesis is unproven, but it offers a possible explanation that is consistent with current scientific thought. We hope that our ideas will stimulate additional studies on the origin of eukaryotic flagella and on investigations of verrucomicrobia. Whether such studies confirm, refine, or replace our hypothesis, they should nevertheless further our understanding of the origin of eukaryotic cells.