Oreoglanis infulatus, a new species of glyptosternine catfish (Siluriformes: Sisoridae) from central Vietnam

A new species of glyptosternine catfish, Oreoglanis infulatus , is described from the Lam River drainage in central Vietnam. The new species is distinguished from all its congeners by possessing the following combination of characters: a dark band running across the anal fin, a lunate and uniformly dark caudal fin, the lower lip lacking a medial notch and with a lobulate posterior margin, maxillary barbel with a rounded tip, length of caudal peduncle 19·0–22·6 % L _S, depth of caudal peduncle 2·6–3·2 % L _S, post-adipose distance 6·8–8·0 % L _S, eye diameter 10·5–12·1 % L _H, 12 principal caudal-fin rays.     

Description of a new Lake Tanganyikan cichlid fish of the genus Cyprichromis(Perciformes: Cichlidae) with a note on sexual dimorphism

Cyprichromis coloratus , a new cichlid species, is described based on 41 type specimens from the Zambian coast of Lake Tanganyika. It differs from Cyprichromis microlepidotus by having fewer scales in the longitudinal line (41–44 v . 59–70 in C. microlepidotus ) and upper lateral line (31–36 v . 47–59), from Cyprichromis leptosoma by more dorsal‐fin spines (14–15 v . 11–13 in C. leptosoma ) and longitudinal line scales (41–44 v . 38–40), from Cyprichromis pavo by fewer dorsal‐fin spines and soft rays (29–31, usually 30, in total v . 30–32, usually 31, in C. pavo ), and from Cyprichromis zonatus by shallower body depth [24·0–28·5 (26·4 ± 1·1)% of standard length v . 24·5–30·5 (28·4 ± 1·3)% in C. zonatus ] and smaller eye [eye length 25·2–30·9 (27·2 ± 1·1)% of head length v . 27·9–33·3 (30·2 ± 1·2)%]. The new species is also separable from C. microlepidotus , C. pavo and C. zonatus by absence of distinct small spots on the body ( v . pearl grey and yellowish small spots along scale rows on body at least in males of C. microlepidotus and C. pavo ), its distinct dichromatism (particularly on the caudal fin) between males of the same population ( v . dichromatism absent in C. zonatus ) and absence of vertical bands ( v . three or four distinct vertical bands beneath dorsal fin base in live males of C. zonatus ). Cyprichromis coloratus n. sp. also exhibits sexual dimorphism, females having a larger head and males having longer pelvic fin, differences which are discussed in relation to reproductive behaviour. A key to the five species of Cyprichromis is included. A lectotype is designated for Cyprichromis leptosoma .     

Ontogeny of the gastrointestinal tract and selected digestive enzymes in cobia Rachycentron canadum (L.)

The ontogeny of the digestive system of cobia Rachycentron canadum from hatching to 22 days post-hatch (dph) (20·1 mm standard length) was examined with light microscopy. The activities of selected pancreatic enzymes were also determined during this period in order to optimize current rearing methods for this species. At hatching (3·6 mm), the digestive tract consisted of a relatively undifferentiated, straight tube positioned dorsally to the yolk sac. The major morphological changes in the digestive tract primarily occurred over the first 1–4 dph (3·6–4·4 mm). During this time, larvae began exogenous feeding (3 dph) and the digestive tract differentiated into five histologically distinct regions: buccopharynx, oesophagus, stomach anlage, anterior intestine and posterior intestine. Yolk reserves were exhausted by 5 dph (4·5 mm) and the oil globule began rapidly decreasing in size disappearing entirely by 9–10 dph (6·3–6·8 mm). Gastric glands differentiated at this time, and by 12 dph (8·1 mm) surface mucous cells of the stomach anlage stained positive for neutral mucosubstances. By 16 dph (11·6 mm), the blind sac (fundic region) of the stomach formed as did the pyloric caecae which initially appeared as a single protrusion of the anterior intestine just ventral to the pyloric sphincter. Generally, enzyme activities (U larva⁻¹) for amylase (0·0–1·8), chymotrypsin (0·0–7902·4), trypsin (0·2–16·6) and lipase (9·3–1319·0) were measurable at or soon after hatching and increased steadily from c. 8–22 dph (5·7–20·1 mm). The results of this study are discussed in terms of current and future weaning practices of this species.     

Loaches of the genus Lepidocephalichthys, from Manipur, with description of a new species

A new species Lepidocephalichthys manipurensis , is described, confined to the Chandel district of Manipur near the adjoining borderland areas of Manipur, India and Burma (Myanmar). It is distinguished by the following combination of characters: a sharp small black dot just above the upper base of the caudal fin; 8–9 dorsal short dark ashy brown bars from occiput to the base of the caudal fin; absence of scales on the vertex of head; caudal fin fork, pectoral, ventral and anal fins are non-immaculate; least depth of caudal peduncle 50·00–60·24% (mean 54·09) of its length and 7·69–8·11% L , S (mean 8·22); caudal fin with 4–5 W-shaped bands: a single dark black stripe from tip of snout to eye; 8–11 spots on the mid lateral line; and 30–31 vertebrae. A key to the identification of lepidocephalid loaches of Manipur is provided.     

Development of European bitterling in the gills of freshwater mussels

The development of bitterling embryos within the unique environment of a freshwater mussel's gills requires a departure from typical cyprinid embryological development. Eggs are large (2·6×1·7 mm), illustrating the low risk of predation, and elliptical; a response to unionid gill morphology and a way of increasing the transfer rates of respiratory and excretory products to and from the tissues. The yolk sac develops elongated lateral processes during early ontogeny; these secure the embryo into the host's interlamellar space. Once the larva is capable of movement (8·2 mm) the lateral processes are lost and the larva becomes less dependent of the host's gills for the provision of oxygen. Hatching (3·3 mm) and pigmentation of the blood (6·4 mm) occur relatively early; this may increase the rate of oxygen supply to the tissues. Pigmentation of the eyes and appearance of the melanophores occurs relatively late (7·4 mm and 7·9 mm, respectively); embryos are not required to detect or avoid predators. Bitterling larvae generally emerge from the host once the yolk sac has been consumed (10·5 mm); this may mark a change in respiratory and nutritional requirements.     

Evidence for the presence of novel β-melatonin receptors along with classical α-melatonin receptors in the fish Rasbora daniconius (Ham.)

Abstract

The effects of melatonin (MT) were examined on the isolated scale melanophores from dorso-lateral (D-L) and band regions of a tropical fish Rasbora daniconius. Our study primarily aimed for further depiction of the signaling receptors involved in MT mediated pigment translocations in the fish. Melanophore Size Index (MSI) was employed as a recording parameter for the responses of melanophores to MT and various antagonists. MT has induced aggregation as well as dispersion in D-L region and aggregation in band region melanophores during summer season. During winter, MT-induced responses were only of aggregatory type in D-L region, while in the band region there was an increase in the sensitivity. The responses of the melanophores to MT were reversible. The aggregation of innervated melanophores induced by MT on the D-L and band regions was partially mediated through the neurotransmitters released under the influence of MT and partially by the specific MT receptors. Luzindole and K185 have completely blocked the aggregatory responses of D-L and band region melanophores. Aggregatory receptors may be of the conventional α-MT type. Dispersion of D-L and band region melanophores induced by MT in the presence of various antagonists and on denervated band region could be the result of activation of β-MT receptors of dispersive nature. Presence of α and β MT receptors is thus indicated in this fish melanophores.     

A medium density microsatellite map of BTA10: reassignment of INRA69

We have developed a genetic map of BTA10 based on 8952 informative meioses for 13 microsatellite markers and the erythrocyte antigen Z. With the exception of OarAE64 , the support for the order of all loci in the map exceeded a LOD > 3·0. The length of the BTA10 genetic map was 87·0 centimorgans (cM). The 14-marker, sex-average map in Kosambi cM was: CSSM38 –8·9- BM1237 –5·2- HH8A –2·6- INRA69 –10·6- TGLA378 –0·8- BM6305 –17·2- TGLA102 –17·9- INRA96 –0·3- CSRM60 –9·2- DIK20 –3·0- EAZ –6·7- CSSM46 –3·7- SRCRSP3 –1·0- OarAE64 with an average interval of 6·70 cM. The microsatellite INRA69 was recently assigned to the pseudoautosomal region of the bovine X chromosome by linkage analysis. However, we found that twopoint support for linkage between INRA69 and 15 X-linked bovine microsatellites was LOD < 0·50 in 529 reciprocal backcross and F₂ fullsib progeny. We performed twopoint analyses of INRA69 against 275 markers distributed throughout the bovine genome and found significant associations with a LOD > 3·0 only between INRA69 and eight BTA10 microsatellite loci. Consequently, we excluded INRA69 from the genetic map of the X chromosome and reassign this microsatellite to BTA10.     

Sensitivity of winter flounder melanophores after removal of the epidermis from in vitro preparations

Winter flounder Pleuronectes americanus has a thick epidermis which was removed from scale slips by incubation in a medium including 1% ethylenediaminetetraacetic acid (EDTA) for up to 2 h. Neurally mediated responses of dermal melanophores to K⁺ and Na⁺, and to exogenous noradrenaline (10^-5 M) were 1·5 to three times faster without the epidermis–mucus barrier; α-melanophore stimulating hormone (MSH) evoked extensive pigment dispersion only without the epidermis. Thus, cellular viability after epidermal removal is not restricted to melanophores, nerve terminals can provide an additional indicator. The sensitivity to α-MSH in vitro , is an important observation since in vivo reports have not indicated that this hormone has a role in the physiological responsiveness of these melanophores in flatfish.     

Heat resistance of Cronobacter species (Enterobacter sakazakii) in milk and special feeding formula

Aim:  To determine D - and z -values of Cronobacter species ( Enterobacter sakazakii ) in different reconstituted milk and special feeding formula and the effect of reconstitution of powdered milk and special feeding formula with hot water on the survival of the micro-organism.
Methods and Results:  Five Cronobacter species (four C. sakazakii isolates and C. muytjensii ) were heated in reconstituted milk or feeding formula pre-equilibrated at 52–58°C for various times or mixed with powdered milk or feeding formula prior to reconstitution with water at 60–100°C. The D -values of Cronobacter at 52–58°C were significantly higher in whole milk (22·10–0·68 min) than in low fat (15·87–0·62 min) or skim milk (15·30–0·51 min) and significantly higher in lactose-free formula (19·57–0·66 min) than in soy protein formula (17·22–0·63 min). The z -values of Cronobacter in reconstituted milk or feeding formula ranged from 4·01°C to 4·39°C. Water heated to ≥70°C and added to powdered milk and formula resulted in a > 4 log₁₀ reduction of Cronobacter .
Conclusions:  The heat resistance of Cronobacter should not allow the survival of the pathogen during normal pasteurization treatment. The use of hot water (≥70°C) during reconstitution appears to be an effective means to reduce the risk of Cronobacter in these products.
Significance and Impact of the Study:  This study supports existing data available to regulatory agencies and milk producers that recommended heat treatments are sufficient to substantially reduce risk from Cronobacter which may be present in these products.     

Influence of different rations and water temperatures on the growth rates of shortfinned eels and longfinned eels

Juvenile (12–152 g) shortfinned eels Anguilla australis and longfinned eels A. dieffenbachia caught in New Zealand streams were fed squid mantle Nototodarus spp. 4 days per week in laboratory experiments. A linear multiple regression equation showed the amount of food eaten (0–2·7% w day⁻¹) explained 77·7% of the variation in specific growth rates (–0·60 to +1·07% w day⁻¹) among individual eels, while previous growth rates, water temperature (10·0–20·6°C), and eel weight (12–152 g) explained a further 5·6, 1·4 and 0·8%, respectively. Growth in length ranged from –0·3 to +0·9 mm day⁻¹. Eels which were starved and then given high rations grew substantially faster than expected. Once growth rates were adjusted for differences in ration and other factors, there were no significant differences in growth rates between species or individual fish. Growth of shortfinned eels fed maximum rations of commercial eel food depended on fish size and water temperatures and ceased below 9·0°C. Growth rates in the wild were substantially less than the maximum possible, after seasonal changes in water temperatures were taken into account, indicating that food supplies and not low water temperatures were controlling growth rates in the wild.     

Characteristics of egg and larval production in captive bluespotted gobies

Spawning of the Hawaiian coral-reef goby Asterropteryx semipunctata was diurnal, occurring at various times throughout the day. Mean length of eggs deposited in nests was 0·76 mm (range 0·67–0·84); mean egg width was 0·47 mm (range 0·41–0·52). Clutch size varied from 296 to 1552 eggs (mean=886±309), and was independent of standard length, total body weight, and body condition. Mean relative clutch size was 1·59 eggs mg^-1 total body weight (range 0·84–2·43). Clutches hatched 4–5 nights after being deposited in a nest. Mean notochord length of newly-hatched larvae was 1·88 mm (range 1·60–2·04). The minimum period of time that elapsed between egg deposition and subsequent growth of a new batch of oocytes to spawning size was 5–6 days, providing a reasonable estimate of minimum spawning interval. Compared with other gobiids, tropical species tend to have shorter incubation periods, smaller eggs and smaller larvae at hatching.     

Ontogenetic changes in temperature preference of Atlantic cod

Final thermal preferendum ( T ) experiments were conducted in a horizontal thermal gradient tank from the beginning of August 2001 to mid‐November 2001 using Atlantic cod Gadus morhua from 6·5 to 79·0 cm fork length ( L _F). The value of T varied significantly ( P  < 0·005) with L _F( T  = 7·23–0·054 L _F), with smaller (younger) fish choosing higher temperatures than larger (older) fish. The preferendum varied from 6·9° C for fish of 6·5 cm to 3·0° C for those of 79·0 cm. Experiments comparing fish positions in the gradient tank between thermal gradients of 0·5–11·0 and 4·5–14·5° C demonstrated that fish positions were determined by temperature selection instead of undesirable tank effects. This study is the first to demonstrate the effect of ontogeny on temperature preferences of a marine fish species.     

A Note on the Diagnosis of Ratoon Stunting Disease of Sugarcane by Negative-Stain Electron Microscopy of the Associated Bacterium

After negatively staining with 1% (w/v) sodium phosphotungstate (pH 6·5) or 1% (w/v) ammonium molybdate (pH 6·5), the cell wall, cytoplasmic membrane and mesosomes of the RSD-associated bacterium obtained from the fibrovascular fluid of infected sugarcane were usually clearly displayed. The cells measured 0·19–0·39 μm (av. 0·27 μm) in width and 0·6–3·4 μm in length. Few mesosomes were visible and the cells were approx. 40% wider (0·27–0·52 μm, av. 0·38 μm) when stained with 1% (w/v) uranyl acetate (pH 3·0–4·2). Freezing and thawing the suspension before negative staining with sodium phosphotungstate did not greatly affect the size of the cells or resolution of the mesosomes. Glycine (0·25 M) as the suspending medium, fixation in 2% (w/w) glutaraldehyde, or placing wet instead of dry specimen grids in the electron microscope resulted in wider cells usually lacking mesosomes.     

Post mortem shrinkage of four species of temperate and tropical marine fishes, without freezing or preservation

The present study indicated significant post mortem decreases in length for four Australian teleost species from temperate to tropical habitats: black bream Acanthopagrus butcheri , King George whiting Sillaginodes punctata , summer whiting Sillago ciliata and redthroat emperor Lethrinus miniatus . Shrinkage averaged 5·0 mm after 24 h (range 0–10 mm) for A. butcheri , 4 mm (0–8 mm) for S. punctata , 2·2 mm (0·7–3·7 mm) for S. ciliata and 5·4 mm (−2·5–15·0 mm) for L. miniatus . For A. butcheri held under three different post mortem treatments, the mean length of fish in all treatments decreased but there was no significant effect of treatment type on the extent of shrinkage. The rate of shrinkage of S. ciliata varied with treatment, but the ultimate extent did not. For A. butcheri shrinkage was most rapid (2·5 mm h⁻¹) between 1 and 2 h postcapture. The results from these studies confirm that a post mortem decrease in length is a common phenomenon, even in fishes that are not frozen or preserved. Such shrinkage has implications for the enforcement of minimum legal length legislation, and may cause bias in biological investigations, including growth estimates from tag and recapture studies.     

Elemental stoichiometry of Drosophila and their hosts

1. Nitrogen (N) and phosphorus (P) availabilities are important ecological determinants of resource use in nature. Despite the wide range of hosts used by species of the genus Drosophila , elemental composition of natural resources of these flies has never been investigated.
2. Total body N and P contents were determined in seven species of wild-caught Drosophila , their natural hosts, and artificial diets routinely used to rear these flies in the laboratory. The flies tested included D. hydei, D. arizonae, D. simulans and D. pseudoobscura collected from rotting fruit (melons), and the cactophilic D. nigrospiracula, D. mojavensis and D. pachea collected from their specific host plants, Saguaro, Organpipe and Senita cactus, respectively.
3. Natural hosts varied in elemental composition, with fruit showing higher N (2·8–4·3% dry mass) and P (0·50–0·67%) levels compared with cacti (0·5–1·6% N; 0·01–0·29% P). No consistent differences in N and P levels were found between healthy and necrotic cactus tissue.
4. Total body N and P also varied among Drosophila species. This variation mirrored the levels of N and P found in the respective hosts and laboratory diets. N:P ratios were consistently lower in female flies compared with conspecific males suggesting phosphorus demands during oogenesis are high.
5. Potential mechanisms by which Drosophila deal with N or P limitation in nature are discussed.     

Development and application of a simple filter paper imprinting technique for the detection and enumeration of colonies of ureolytic micro-organisms

A rapid, simple and inexpensive method has been devised to determine the proportion of colonies of ureolytic organisms in cultures of complex microbial populations. Spiral plated cultures displaying well separated colonies are tested for ureolytic micro-organisms by imprinting the colonies onto filter papers impregnated with a solution of 1 mol/l urea and phenol red (0·1% w/v) in 0·1 mol/l phosphate buffer (pH 6·8). A rapid colour change indicates ureolytic activity. The proportion of ureolytic colony-forming units in cultures of saliva specimens from 90 school children ranged from less than 1% to 40% (mean 9·9%± 7·7). Saliva and dental plaque specimens from 16 adult subjects were also tested and the occurrence of urease-positive organisms was substantially less in plaque (3·6%± 3·7, range 0·1–12) than saliva (18·7%± 13·8, range 1·3–51). The predominant ureolytic oral species was Streptococcus salivarius , 75 (54·7%) of 137 tested isolates being urease-positive.     

Nitrogenous excretion in the Antarctic plunderfish

The nitrogenous excretion rates (total ammonia nitrogen, urea, and primary amines) of plunderfish Harpagifer antarcticus were related significantly to length and to wet mass (mass exponents of 0·94, 1·01, 1·07 and 0·93 for total ammonia nitrogen, urea, primary amines, and total nitrogen, respectively). The routine total ammonia excretion rates [22·23 & 2·0 mg N kg⁻¹ day⁻¹ (mean±S.E.)] of plunderfish measured in Antarctica are 10–69% lower than those of comparable non-polar species. Plunderfish are ammonotelic, but the proportion of the total nitrogenous waste attributable to each category was variable between individuals. On average (ranges in parentheses), total ammonia nitrogen, urea, and primary amines accounted for c .82 (57–97), 13 (2–28), and 5 (0·6–22)%, respectively, of the total nitrogen excreted. Polar fish differ from their non-polar relatives only in the rate, and not the nature, of their nitrogenous waste excretion processes.     

Haematology and leucocyte morphology of wild caught Thunnus maccoyii

The haematology of wild southern bluefin tuna Thunnus maccoyii was described using blood samples collected from fish immediately after they were caught. Cytology and cytochemistry revealed that the blood in peripheral circulation is comprised of erythrocytes, reticulocytes, ghost cells, lymphocytes, thrombocytes, eosinophilic granulocytes, neutrophilic granulocytes and monocytes. Reference ranges established were 41·09–55·50% for haematocrit, 0·62–3·00% for leucocrit, 13·25–17·92 g dl⁻¹ for haemoglobin and 2·1–2·9 million erythrocytes μl⁻¹ for erythrocyte count. Differential cell counts showed 94·58 ± 2·15% erythrocytes, 3·99 ± 1·44% leucocytes and 1·43 ± 1·03% thrombocytes (mean ±  s . d .). Normal ranges for differential leucocyte counts were 0·00–5·45% for neutrophils, 0·69–12·06% for eosinophils, 0·00–5·03% for monocytes, 46·97–74·32% for lymphocytes and 14·47–43·92% for thrombocytes. Erythrocyte indices, leucocyte types and cytochemistry were comparable to other species of scombrids. Packed cell volume was sensitive to the physiological state of the fish and to sample handling technique.