Ariel Diamant - Academia.edu (original) (raw)

Papers by Ariel Diamant

Helgoland Marine Research, 1999

Journal of Fish Diseases, 2008

Failure to inflate the swim bladder is regarded a major obstacle in the rearing of many fish spec... more Failure to inflate the swim bladder is regarded a major obstacle in the rearing of many fish species. We present a study of swim bladder non-inflation (SBN) in angelfish, Pterophyllum scalare. A normal developing primordial swim bladder was first discernable at the end of the first day post-hatch (p.h.) as a cluster of epithelial cells with a central lumen, surrounded by presumably mesenchymal cells. Initial inflation occurred on the fourth day p.h. Prior to inflation the swim bladder epithelium consisted of an outer squamous and inner columnar layer. Cells of the inner layer were filled at their basal region with an amorphous material, which disappeared upon inflation. A pneumatic duct was absent, and larvae presented no need to reach the water surface for inflation, suggesting that angelfish are pure physoclists. A model for the role of the amorphous material in normal initial inflation is proposed. Abnormal swim bladders were apparent from the fourth day p.h., and methylene blue (MB) at a concentration of 5 ppm significantly increased the prevalence of SBN. Histologically, abnormal swim bladders in larvae hatched in 5 ppm MB could not be distinguished from those in fish raised under routine conditions (0.5 ppm MB). We suggest that MB may have a teratogenic effect in angelfish.

Bulletin of The European Association of Fish Pathologists, 1989

Diseases and disorders of finfish in cage culture

This chapter presents the viral, bacterial and parasitic diseases of warm water fish cultured in ... more This chapter presents the viral, bacterial and parasitic diseases of warm water fish cultured in floating net pens and cages. Focus is given on the life cycle, clinical signs, diagnosis, treatment and impact on fish production of these diseases.

Israeli Journal of Aquaculture - Bamidgeh, 2006

Traditionally, the most common approach to diagnosis of microbial fish pathogens has relied on in... more Traditionally, the most common approach to diagnosis of microbial fish pathogens has relied on in vitro isolation of the microorganism and the information provided by its phenotypic features. However, viruses are generally highly species-specific and established cell lines do not neces- sarily show cytopathic effect, many species of bacteria are difficult or impossible to culture in vitro, while parasitic microorganisms often have a complex life cycle that requires propagation in live hosts. An increasing number of microbial pathogens are identified today by molecular meth- ods, without the need for isolation. A PCR direct method for detection and identification of Mycobacterium marinum based on the 16S rRNA gene sequence was successfully developed already 13 years ago at NCM. Comparison of the 16S rRNA sequence of Streptococcus iniae isolates revealed that, despite phenotypic, biochemical and pathogenetic similarities, marine and freshwater isolates were different strains. With tim...

Diseases of Aquatic Organisms, 1997

F~sh-to-fish transmission of the marine myxosporean Myxidium lee; was experinlentally demonstrate... more F~sh-to-fish transmission of the marine myxosporean Myxidium lee; was experinlentally demonstrated in sea bream Sparus aurata L. A group of specif~c-pathogen-free (SPF) fish of-11 g each were placed in a wire-mesh cage immersed In a tank holding infected fish. A second group was placed in a tank receiving water discharged from another tank holding diseased fish. After 9 wk, the fish were sacrificed and 12 of the 38 (31.6%) test fish from the mesh cage were found to harbor trophozoites, sporoblasts and spores in the posterior gut epithelium, as was readily diagnosed by standard paraffin histology. Of the fish exposed to water discharge, 10 out of 30 (33.3%) showed similar infection. None of the fish examined displayed any proliferative stages of the parasites in the blood, spleen, kidney, liver or gill samples. All of 100 control fish examined remained uninfected. A third group of SPF fish was fed once daily for 7 d on pieces of freshly dissected M. leei-infected gut, after which the fish were maintained on a commercial pellet diet for a further 4 wk. Control f~s h in this experlrnent were fed only commercial pellets for 5 wk. The fish were sacrificed after 5 wk, and 4 out of 30 test fish (13 %) were found to be infected. All control fish remained uninfected. Examination of the water sampled from all tanks in which infected fish were held revealed presence of exfoliated gut tissue and mucus casts containing trophozoites, sporoblasts and spores of M. leei. Examination of existing potential intermediate hosts yielded definitively negative results for actinosporeans. It is suggested that M. lee1 is transmitted between fish by ingestion of excretions from infected fish. The results reveal that sharing facilities with diseased fish as well as exposure to contaminated water is a route for parasite transmission. In general contrast to the freshwater myxosporeans studied to date, the present study of a marine species provides evidence that d~rect transmission can take place without need for actinosporean developnlent in an alternate (oligochaete) host. It is suggested that this may be a model for the development of other marine myxosporeans as well.

Journal of Plant Physiology

Ecologically relevant low UV-B is reported to alter reactive oxygen species metabolism and anti-o... more Ecologically relevant low UV-B is reported to alter reactive oxygen species metabolism and anti-oxidative systems through an up-regulation of enzymes of the phenylpropanoid pathway. However, little is known about low UV-B-induced changes in carotenoid profile and their impacts on light harvesting and photoprotection of photosystem II (PSII) in plants. We investigated carotenoids profile, chlorophyll pigments, phenolics, photosynthetic efficiency and growth in Arabidopsis thaliana (Col-0) plants grown under photosynthetically active radiation (PAR), PAR+ ultraviolet (UV)-A and PAR+UV-A+B regimes for 10 days in order to assess plant acclimation to low UV-B radiation. A chlorophyll fluorescence assay was used to examine UV-B tolerance in plants further exposed to acute high UV-B for 4 and 6 h following a 10-day growth under different PAR and UV regimes. We found that both PAR+ UV-A and PAR+UV-A+B regimes had no negative effect on quantum efficiency, electron transport rate, rosette diameter, relative growth rate and shoot dry weight of plants. Chronic PAR+ UV-A regime considerably (P < 0.05) increased violaxanthin (26 %) and neoxanthin (92 %) content in plants. Plant exposure to chronic PAR+UV-A+B significantly (P < 0.05) increased violaxanthin (48 %), neoxanthin (63 %), lutein (33 %), 9-cis ß-carotene (28 %), total ß-carotene (29 %) and total phenolics (108 %). The maximum photochemical efficiency (Fv/Fm) in leaves was found to be positively correlated with total phenolics (rho = 0.81 and rho = 0.91, P < 0.05 for 4 and 6 h, respectively) and non-photochemical quenching (qN) (rho = 0.81 and rho = 0.84, P < 0.05 for 4 and 6 h, respectively) in plants exposed to acute high UV-B for 4 and 6 h following a 10-day growth under chronic PAR+UV-A+B. There was also a significant positive correlation (rho = 0.93, P < 0.01) between qN and lutein content in the plants exposed to acute high UV-B stress for 4 h following plant exposure to chronic PAR+UV-A+B. The findings from our study indicate that plants grown under chronic PAR+UV-A+B displayed higher photoprotection of PSII against acute high UV-B stress than those grown under PAR and PAR+ UV-A regimes. An induction of phenolics and lutein-mediated development of qN were involved in the photoprotection of PSII against UV-B-induced oxidative stress.

Annals of botany, 2005

New maize (Zea mays) hybrids outperformed old ones even at reduced N rates. Understanding the mec... more New maize (Zea mays) hybrids outperformed old ones even at reduced N rates. Understanding the mechanisms of the differences in performance between newer and older hybrids under N deficiency could provide avenues for breeding maize cultivars with large yield under N deficiency, and reduce environmental pollution caused by N fertilizers. N deficiency effects on grain weight, plant weight, harvest index, leaf area and photosynthetic traits were studied in the field for six maize hybrids released during the past 50 years to compare their tolerance and to explore their physiological mechanisms. N deficiency decreased grain yield and plant weight in all hybrids, especially in the older hybrids. However, there was no significant difference in harvest index, rate of light-saturated photosynthesis (Psat) 20 d before flowering, leaf area or plant weight at flowering between the N-deficient and control plants of all hybrids. Dry matter production after flowering of the N-deficient plants was s...

Journal of the American Oil Chemists’ Society, 1999

Transesterification of soybean oil with methanol has been carried out in the presence of heteroge... more Transesterification of soybean oil with methanol has been carried out in the presence of heterogenized alkylguanidines as catalysts. The alkylguanidines were anchored to modified polystyrene or siliceous MCM-41, encapsulated in the supercages of zeolite Y, or entrapped in SiO 2 sol-gel matrices. The catalytic activity of these catalysts was compared with that of their homogeneous counterparts, showing that the yields of methyl esters obtained in the homogeneous phase can be obtained with the guanidines anchored to the supports after longer reaction times. The catalysts prepared by immobilization of alkylguanidines in microporous systems showed diffusion restrictions for the vegetable oil as well as the low stability of the inorganic framework.

Marine ecology progress series. Oldendorf, 1984

The venomous Red Sea blenny Meiacanthus nigrolineatus is avoided by predatory reef fishes and is ... more The venomous Red Sea blenny Meiacanthus nigrolineatus is avoided by predatory reef fishes and is mimicked by other blenniid species. M. nigrolineatus juveniles (< 20 mm) possess a distinct colour patterndark stripes and a basicaudal blotchwhich is different from that of adults and closely resembles the colour patterns of various cardinal fish species (Apogonidae), among whose shools it is frequently found. It is suggested that solitary fish species may mimic schooling species and gain protection by mingling into their schools or aggregations. Some hitherto unclassified cases of mimicry are discussed and included in a new type of mimicry: school-oriented mimicry.

Israeli Journal of Aquaculture (Bamidgeh), 2005

As from January 2010 The Israeli Journal of Aquaculture-Bamidgeh (IJA) will be published exclusiv... more As from January 2010 The Israeli Journal of Aquaculture-Bamidgeh (IJA) will be published exclusively as an on-line Open Access (OA) quarterly accessible by all AquacultureHub (http://www.aquaculturehub.org) members and registered individuals and institutions. Please visit our website (http://siamb.org.il) for free registration form, further information and instructions. This transformation from a subscription printed version to an on-line OA journal, aims at supporting the concept that scientific peer-reviewed publications should be made available to all, including those with limited resources. The OA IJA does not enforce author or subscription fees and will endeavor to obtain alternative sources of income to support this policy for as long as possible.

The word symbiosis is from the Greek meaning "living together", but present usage means... more The word symbiosis is from the Greek meaning "living together", but present usage means two dissimilar organisms living together for mutual benefit. Ecologists prefer to use the term mutualism for this. The significance of symbiosis and its crucial role in coral reef function is becoming increasingly obvious in the world's warming oceans. A coral colony consists of numerous coral polyps, each like a tiny sea anemone that secretes calcium carbonate to form the hard skeletal part of coral. The polyps succeed in developing into a coral colony only by forming a symbiotic relationship with a free-living yellowish brown algal cell that has two flagella for locomotion. These cells penetrate the coral tissue (the flagella drop off) to live in the inner layer of the coral polyps collectively as zooxanthellae and give the yellowish brown color to the coral colony. As plants, they use the carbon dioxide and water from the respiration of the polyps to carry out photosynthesis that...

Since spring 1998, a new disease causing high mortality has afflicted cultured ornamental and com... more Since spring 1998, a new disease causing high mortality has afflicted cultured ornamental and common carps (Cyprinus carpio) in Israel. The clinical signs of the disease are fatigue, gasping movements in shallow water, gill necrosis, sunken eyes, pale patches on the skin and increased mucus secretion. The disease was experimentally transmitted to koi and common carp of various ages by injection with affected tissue filtrates, cohabitation trials and exposure to the isolated viral agent. Immersion of healthy fish in tanks containing 2.7 x 10 4 plaque forming units (PFU) per l or intraperitoneal injection (0.2 ml) of a viral inoculum of 1000 PFU/ml were sufficient to induce the terminal disease in over 80% of the fish. Here we report that the disease is restricted to C. carpio, that young fish of 2.5 g and 6 g are more sensitive to the virus than adults (230 g) and that the virus remains active in the water for at least four hours.

The goby Tenacigobius yongei (Davis & Cohen, 1968) has been described from Borneo and Hawai. It l... more The goby Tenacigobius yongei (Davis & Cohen, 1968) has been described from Borneo and Hawai. It lives on the antipatharian sea whip Cirhipathes sp., sharing this ecological niche with the palaemonid shrimp Pontonides unciger (Calman) (Davis & Cohen, 1968). Although the sea whip and associated shrimp have been known from the Red Sea for many years, this goby has surprisingly not been recorded from the Red Sea or the Western Indian Ocean. This small goby has probably been overlooked by scientists, as have many other common gobies recently discovered(Goren, 1983), due to its small size. During a redent study of the taxonomy and ecology of gobies living in association with sessile invertebrates, carried out in the northern Red Sea, specimens of T. yongei were collected and identified, and the species is reported here as being a new record for the Red Sea

Israeli Journal of Aquaculture - Bamidgeh

Zoology in the Middle East

Swarms of striped eel catfish were observed for the first time in Eilat at the northern tip of th... more Swarms of striped eel catfish were observed for the first time in Eilat at the northern tip of the Gulf of Aqaba, Red Sea in summer 2017. Taxonomic and genetic studies revealed them to belong to Plotosus japonicus Yoshino & Kishimoto, 2008. This is the first report of this species outside the Japanese archipelago. Molecular comparisons (mtDNA COI) of this population with previously published samples show that this species is actually present throughout the Indo-Pacific and provide indication that this genus includes two of ambiguous identity species that await further examinations.

Frontiers in Marine Science

Cell Differentiation

The uptake of cortisol and the kinetics of hormone-receptor interaction in the cytosol and cell n... more The uptake of cortisol and the kinetics of hormone-receptor interaction in the cytosol and cell nucleus were investigated in the intact tissue in organ culture. Cortisol is concentrated by the neural retina. The accumulation of the free steroid is temperature dependent hut the effect of tcmperaturc decreases with the incrcasc of cortisol in medium. Cortisol binding to specific receptors ill the cytosol shows a sigmoidal type of kinetics which correlates well with the kinetics of glutamine-synthetase induction by cortisol. The temperature dependent translocation of the receptor-hormone complexes to the nuclei and the effect of detergents on the binding to nuclei are presented.