Showing papers on "Gill published in 1988"
TL;DR: It was concluded that the most typical localization of CA is on the apical surface of the lamellar epithelium lying in contact with the environment, suggesting that one of the main roles of gill CA may be to facilitate the diffusion of CO2 from blood to water.
Abstract: Carbonic anhydrase was purified from the gills (CAB) of the rainbow trout Salmo gairdneri and from erythrocytes (CAE) of the fresh water carp Cyprinus carpio. The purification of the isozymes was confirmed by SDS acrylamide gel electrophoresis. Antibodies against the purified CAB and CAE were then raised in rabbits. Specificity was verified by immunoblotting. No cross-reaction was found between them, using the immunodot technique. CAB antiserum was used to specifically localize gill CA in the trout. Immunoperoxidase labelling revealed a concentration of enzyme on the apical region of the outer layer of the gill epithelial cells. The inner layer of the epithelium was only weakly positive. Results obtained using the immuno-gold technique confirmed the immunoperoxidase labelling: there was a concentration of label in the apical regions of chloride cells. In mucous cells, only the mucous granules were labelled. In the lamellae, the label was distributed in the apical part of the pavement cells. The villi and microplicae were strongly positive. CAE antiserum stained the red blood cells. The discrepancy between histochemical localization in the gill or in the opercular skin of killifish and our present immunolocalization was discussed. It was concluded that the most typical localization of CA is on the apical surface of the lamellar epithelium lying in contact with the environment. The result suggests that one of the main roles of gill CA may be to facilitate the diffusion of CO2 from blood to water.
110 citations
TL;DR: It was concluded that the Atlantic salmon develops in fresh water most of the ultrastructural modifications of the gill epithelium which in most euryhaline fish are triggered by exposure to seawater.
Abstract: To elucidate the ultrastructural modifications of the gill epithelium during smoltification, gills of the Atlantic salmon (Salmo solar) were examined by electron microscopy at three stages of this process, which were defined as follows: “parrs” were freshwater fish that had not yet started their transformation; “freshwater smolts” were freshwater fish that were ready to enter seawater; and “seawater smolts” were smolts that had been transferred from fresh water and maintained for 4 days in seawater (35%).
In the gill epithelium of parrs, there were two types of chloride cells. The large chloride cells contained deeply stained mitochondria and numerous apical, irregular, dense, membrane-bound bodies that formed 77% of the chloride cell population and were distinguished easily from small chloride cells that have distinctly paler mitochondria and no dense bodies in their apical cytoplasm. In freshwater smolts, the large chloride cells formed 95% of the chloride-cell population. In contrast to the small chloride cells that were not modified, they almost doubled in size. Their tubular system developed extensively to form a tight network with regular meshes significantly smaller than those observed in parr chloride cells. Forty percent of the large chloride cells were associated with a new type of cell, the accessory cell, to which they were bound by shallow apical junctions. Half of these accessory cells were not seen to be in contact with the external medium, In seawater smolts, 80% of the large chloride cells were associated with accessory cells. Most accessory cells reached the external medium and sent numerous cytoplasmic interdigitations within the apical portion of the adjacent chloride cells. As a result, a section through the apical portion of the chloride cells and their associated accessory cells revealed a mosaic of interlocked cell processes bound together by an extended, shallow apical junction.
It was concluded that the Atlantic salmon develops in fresh water most of the ultrastructural modifications of the gill epithelium which in most euryhaline fish are triggered by exposure to seawater. The effective transfer into seawater would act only as a final stimulus to achieve some adequacy between the freshwater smolt and its new environment.
96 citations
TL;DR: Correlations were made between differences in behavior and morphological adaptations of their gills to tolerate terrestrial exposure of the three mudskippers.
Abstract: The three mudskippers—Periophthalmus chrysospilos, Boleophthalmus boddaerti, and Periophthalmodon schlosseri—occupy the same macrohabitat in Singapore but have different behaviors. Correlations were made between differences in behavior and morphological adaptations of their gills to tolerate terrestrial exposure.P. schlosseri has branched gill filaments, thick gill rods, and fused secondary lamellae which enable them to better adapt to a terrestrial than an aquatic environment. Of the three mudskippers, P. chrysospilos gills are the shortest. They are also bent and poorly developed for aquatic respiration. B. boddaerti gills consist of numerous long filaments and have the largest gill area of the three mudskippers. These features suggest that B. boddaerti gills function more efficiently as a respiratory organ in water than in air.Gill surfaces of all three mudskippers are highly convoluted to increase surface area.
80 citations
TL;DR: Acute effects of the heavy metals cadmium, copper, lead, cobalt, iron, and silver, and the organic pollutants PCB, DDT, and dieldrin on the gill of the mussel Mytilus edulis were studied in aquaria in brackish water.
63 citations
TL;DR: Cellular and subcellular responses of the marine burrowing bivalve Venus verrucosa collected from the north-eastern coastline of Malta, after exposure to petroleum hydrocarbons were investigated, including an increase in cell volume and activity of gill mucocytes as well as in the number of haemocytes in gill blood sinuses are discussed.
Abstract: Cellular and subcellular responses of the marine burrowing bivalve Venus verrucosa collected from the north-eastern coastline of Malta from January to June 1985, after exposure to petroleum hydrocarbons (PHC) were investigated. After long-term exposure to 100 μgl-1 of water-accomodated fractions (WAF) of crude oil, PHC were found to accumulate most rapidly in the digestive gland and then in the gills, with saturation levels being reached within 100 d of exposure in both cases. PHC accumulation, both in the mantle and muscle tissues, was more gradual and consistent throughout the whole exposure period. After 150 d of exposure, the digestive cells of the digestive gland were significantly reduced in height (atrophy) and exhibited reduced lysosomal membrane stability. After 144 h of exposure to higher concentration of PHC (820 and 420 μgl-1), several cytological effects were recorded, including an increase in cell volume and activity of gill mucocytes as well as in the number of haemocytes in gill blood sinuses. There was also evidence of damage to the epithelial lining of the foot, stomach and style sac and marked atrophy of the digestive cells of the digestive gland. The significance of such responses is discussed.
61 citations
TL;DR: A study was undertaken to ascertain whether any relationship existed between gill lesions and gill parasites in cod following chronic exposure to petroleum hydrocarbons.
Abstract: Fish gills appear to be more susceptible than other tissues to toxicants. The latter include petroleum aromatic hydrocarbons, which can induce lesions characterized by excessive mucus secretion, hyperplasia, fusion of secondary gill lamellae and capillary dilation. Fish are also natural hosts to several species of ectoparasites, especially monogeneans which live among the gill filaments. A previous study on the interrelation of water quality, gill parasites and gill pathology provided evidence that fish living in habitats degraded by pollutants such as Biscayne Bay, Florida, were heavily infested with monogeneids especially when gill lesions were severe. Atlantic cod, Gadus morhua, are hosts to monogeneans. The authors reported previously that crude oil fractions induced gill lesions in cod and also affected some gastrointestinal parasites. In the light of these reports, a study was undertaken to ascertain whether any relationship existed between gill lesions and gill parasites in cod following chronic exposure to petroleum hydrocarbons.
60 citations
TL;DR: Exposure to prevailing levels of this inert clay particle, even for periods as long as 64 days, probably has little direct effect on gill structure at the light microscope level, the authors conclude.
Abstract: . Juvenile rainbow trout were exposed to 36, 171, 1017 and 4887 mg/1 of suspended kaolin clay for 64 days. Gills were analysed qualitatively and quantitatively using histology. Branchial pathology was absent at all sample times in fish exposed to 36, 171 and 1017 mg/1 kaolin, although intracellular kaolin was visible within filament and lamellar epithelium in gills exposed to 171, 1017 and 4887 mg/1 kaolin at 4, 8, 16, 32 and 64 days. Lesions were found in gills exposed to 4887 mg/1 kaolin at 16 and 32 days but the marked lamellar proliferation was associated with moderate to large numbers of protozoa identified as Ichthyobodo necator. Gills regained normal architecture by 64 days despite continued exposure to kaolin. It is suggested that while the gill lesions were probably a direct result of protozoan infection, kaolin was indirectly responsible for creating a favourable environment for protozoan colonization. The recovery of normal architecture and reduction of protozoan numbers between 32 and 64 days was probably a function of increased mucus secretion, immune response and turnover of branchial epithelium. The authors conclude that exposure to prevailing levels of this inert clay particle, even for periods as long as 64 days, probably has little direct effect on gill structure at the light microscope level. The action of non-inert and organic particles remains to be investigated.
56 citations
TL;DR: Activities of two enzymes considered to be involved in NaCl regulation, Na+–K+ ATPase and carbonic anhydrase, were localized in gill epithelia of 14 teleost, 2 agnathan, and 1 shark species through light microscopic histochemistry.
Abstract: Activities of two enzymes considered to be involved in NaCl regulation, Na+–K+ ATPase and carbonic anhydrase, were localized in gill epithelia of 14 teleost, 2 agnathan, and 1 shark species through light microscopic histochemistry. Findings were confirmed by use of appropriate inhibitors (ouabain, acetazolamide). Na+–K+ ATPase activity was detected in chloride cells of most marine teleost species (six of eight) and of marine leopard shark and hagfish, but never in freshwater fish gills. In general, this finding agrees with past biochemical assays showing gill Na+–K+ ATPase activity to be highest in marine teleosts. Staining for carbonic anhydrase took one of three patterns among species: gill pavement cells or chloride cells, or both, were stained. Interspecific distribution of these patterns bore little relation to taxonomy or to habitat salinity, although chloride cells of euryhaline teleosts seemed more likely to stain than chloride cells of stenohaline teleosts, freshwater or marine. Given the lack of...
56 citations
TL;DR: A morphometric study of gill structures and of the body musculature during the first weeks after hatching was carried out on larvae of six cyprinid species, finding that the metabolism of the swimming muscles is almost entirely aerobic.
Abstract: A morphometric study of gill structures and of the body musculature during the first weeks after hatching was carried out on larvae of six cyprinid species: Leuciscus cephalus, L. leuciscus, Rutilus rutilus, Alburnus albumus, Chondrostoma nasus and Abramis brama. In all species a unicellular layer of red muscle fibres covers the central muscle mass; this layer is of greatest extent shortly after hatching but diminishes gradually in mass by contracting towards the lateral region of the body until it merges with (or gives rise to) the adult red muscle fibres proper. There is a close relationship between the rate of differentiation of gill structures and the rate at which the larval red muscle layer disappears, the pattern of this relationship reflecting the life style of the species. The longer the larvae delay the start of their free-swimming existence after hatching (which in A. alburnus may be as long as 10 days) the longer does the red layer of muscle fibres serve as the organ of gas exchange and the longer is gill development suppressed. It appears that the metabolism of the swimming muscles is almost entirely aerobic so long as gas exchange takes place across the whole body surface, the glycolytic capacity of the central muscle mass developing only slowly in conjunction with the switch from red layer to gills as the major respiratory organ.
52 citations
TL;DR: Rod-shaped bacteria were consistently observed by transmission electron microscopy in the locomotory test of larvae and in the perivisceral cavity of post-larvae of Solemya reidi, a gutless protobranch bivalve known to possess intracellular chemoautotrophic bacterial symbionts in the adult gill.
Abstract: Rod-shaped bacteria were consistently observed by transmission electron microscopy in the locomotory test of larvae and in the perivisceral cavity of post-larvae of Solemya reidi, a gutless protobranch bivalve known to possess intracellular chemoautotrophic bacterial symbionts in the adult gill. Bacteria develop within granular vesicles in the larval test, where they either remain to be ingested at metamorphosis, or are released into the space separating the test and embryo, to be subsequently ingested through the larval mouth. In either case, bacteria lie within the perivisceral cavity following metamorphosis. Bacteria were not seen either in or on gametes or in gills of juveniles. It is hypothesized that these bacteria represent a transmission stage of the gill symbionts present in adult S. reidi and are not evident in gametes or gills of juveniles due to cryptic packaging within granular vesicles. Perpetuation of this symbiosis would therefore be assured through vertical transmission, as is typical of other marine invertebrate-bacteria endosymbioses.
40 citations
TL;DR: Results of aluminum speciation suggest that both labile and non-labile fractions are responsible for the induction of gill lesions, and low levels of aluminum may protect fish from the effects of high hydrogen ion concentration.
Abstract: The objective was to determine the effects of acid and aluminum in acidified hard and soft water on the histology and morphometry of rainbow trout gills, and to determine relevant toxicity indicators within the gill tissue. Acid and aluminum promoted measurable primary epithelial hyperplasia which proved to be a reliable biological indicator of acid and aluminum contamination and possibly of some predictive value. Low levels of aluminum and acid resulted in hypertrophied chloride cells, suggesting a role in adapting to the contaminants. High concentrations of aluminum (>10 μmolI-1) caused chloride cell necrosis and consequently a decline in cell numbers over time. Aluminum precipitates accumulating within the chloride cell cytoplasm probably lead to impaired function prior to cell degeneration. The morphological alterations resulted in a decrease in water space between secondary lamellae (up to 40% within 14 d) which may reduce the efficiency of gas exchange. Twice the aluminum was required in hard water to elicit a similar soft water tissue response. Pathological changes were more severe with aluminum at pH 5.2 than at pH 4.7; results of aluminum speciation suggest that both labile and non-labile fractions are responsible for the induction of gill lesions. Low levels of aluminum may protect fish from the effects of high hydrogen ion concentration.
TL;DR: Air-breathing crustaceans maintain relatively low carbon dioxide levels in the haemolymph, either by retaining an aquatic route for its elimination over the reduced gills or by blowing it off across the lung to reduce rates of water loss in air.
Abstract: The evolution of air-breathing in land crabs is associated with a progressive shift in the primary site of respiratory gas exchange from the diffusion-limited gills used for water-breathing, via a simple ‘cutaneous’ lung surface to the perfusion-limited, invaginated lung described in the mountain crab, Pseudothelphusa garmani. The reduced diffusion limitation over the lungs facilitates oxygen transfer from air to the tissues at lower ventilation rates but is associated with accumulation of carbon dioxide. A potential respiratory acidosis is buffered by the respiratory pigment haemocyanin and by elevation of haemolymph bicarbonate levels. These changes parallel those described in vertebrates but air-breathing crustaceans maintain relatively low carbon dioxide levels in the haemolymph, either by retaining an aquatic route for its elimination over the reduced gills or by blowing it off across the lung. Maintenance of low carbon dioxide levels may be associated with a limited capacity to buffer against an acidosis due to low levels of circulating haemocyanin (i.e. crustaceans lack red blood cells). This may ultimately limit their survival in air as an acidosis will reduce oxygen transport due to a marked Bohr effect on haemocyanin. The primary role of an invaginated lung may be to reduce rates of water loss in air.
TL;DR: Analysis of chloride cell number and size in gills and of binding characteristics of AVT revealed parallel changes with external salinity, taken as evidence for the direct intervention of neurohypophysial peptides on the gill epithelium of teleost fishes.
Abstract: Binding of 125I-labelled arginine vasotocin (AVT) was studied in isolated intact gill cells obtained from eels (Anguilla anguilla) adapted to fresh water (FW) or to sea water (SW). Experiments carried out at 20 degrees C showed maximum and stable binding beyond 10 min of incubation. Specific binding, determined by using labelled peptide in the presence or absence of an excess of unlabelled hormone, represented 30-50% of total and was reversible, with a half-time of less than 5 min. Scatchard plot analysis revealed the presence of a single population of saturable, high-affinity sites. Maximum binding capacity (Bmax: fmol AVT/10(6) cells) and dissociation constant (Kd: nM) were respectively 5.16 and 3.21 in FW and 24.25 and 1.05 in SW. Analysis of chloride cell number and size in gills and of binding characteristics of AVT revealed parallel changes with external salinity. These results are taken as evidence for the direct intervention of neurohypophysial peptides on the gill epithelium of teleost fishes.
TL;DR: The electron microscopic examination of the abnormally dark regions of the gill from hard clam, Meretrix lusoria, revealed that there were virus-like particles present in the cytoplasm of necrotic cells as mentioned in this paper.
Abstract: The electron microscopic examination of the abnormally dark regions of the gill from hard clam, Meretrix lusoria, revealed that there were virus-like particles present in the cytoplasm of necrotic cells. With TO-2 cell line, the virus was isolated. Electron microscopic examinations showed that there were no detactable differences in morphology and location of virions in the gill cells of clam and TO-2 cells except that virus crystals were infrequently observed in clam gills. The subsequent serological and biochemical studies indicated that all the virus isolates from clam were similar to AB IPNV (infectious pancreatic necrosis virus). These studies represent the first complete characterizations of virus isolated from clam in Taiwan.
TL;DR: Gills of affected fish were distinctly swollen and white in appearance, indicating that the gills were not functional as gas exchange organs, thus extending the range to the Antarctic and also the Southern Hemisphere.
Abstract: X-cell tumours have been described previously from teleost fish of the Northern Hemisphere, in which they occurred as lesions of the skin, pseudobranchs or gills. The present study describes X-cell tumours from the gills of an Antarctic teleost, Pagothenia borchgrevinki, thus extending the range to the Antarctic and also the Southern Hemisphere. Gills of affected fish were distinctly swollen and white in appearance, indicating that the gills were not functional as gas exchange organs. The affected gill tissue contained large numbers of X-cells, large spherical cells with a distinct extracellular coat and many densely staining membrane-bound granules. The possible origin of the cells is discussed.
TL;DR: Focal swellings demonstrated a dose-dependent relationship, their numbers being greatest at the higher exposure level, and marked fragmentation of pavement cell microridge patterns and swelling of the respiratory epithelial cells was evident at the 10-μg 1−1 exposure level.
Abstract: Windowpane flounder, Scophthalmus aquosus Mitchill, were exposed for 60 days to 5 or 10 μg 1−1 mercury and gill samples were examined by scanning electron microscopy. The response of the gill epithelium was different at the two levels of mercury exposure. The number of chloride cell apical pits and gill filaments bearing ‘cratered’ epithelial cells increased at the 5-μg 1−1 level and decreased at the higher exposure level.
Focal swellings demonstrated a dose-dependent relationship, their numbers being greatest at the higher exposure level. Marked fragmentation of pavement cell microridge patterns and swelling of the respiratory epithelial cells was evident at the 10-μg 1−1 exposure level.
TL;DR: Branchial lesions together with coagulation film anoxia are likely to result in serious respiratory distress and related tissue hypoxia in the Cd-exposed fish.
TL;DR: Gill morphology of brown trout inhabiting a periodically acidified brook in the eastern part of Bavaria, Federal Republic of Germany, wasuded by light and electron microscope and showed an increase in chloride cells In the secondary lamellar epithelium and an attachment of opposing cells, epithelia1 or chloride cells in the respiratory epithellium of neighbouring secondary lamella.
Abstract: Gill morphology of brown trout Salmo h t t a m. fano inhabiting a periodically acidified brook in the eastern part of Bavaria, Federal Republic of Germany, was s tuded by light and electron microscope. Gills from brown trout caught at a snowmelt period (pH 4.9; A1 0.8 mg I-') were characterized by an increase in mucous cells and excessive mucus production w h c h caused the fusion of secondary lamellae. Gills from brown trout sampled from the same brook in a dry period in September (pH 6.2 to 6.5; A1 0.1 mg I-') showed an increase in chloride cells In the secondary lamellar epithelium and an attachment of opposing cells, epithelia1 or chloride cells in the respiratory epithelium of neighbouring secondary lamellae.
TL;DR: Gill histopathology was examined in three groups of parr of coho salmn maintained for 30 days in suspended wood debris collected from an estuarine log sorting site, and histopathologic responses were indexed by percentage of gill filaments affected.
Abstract: Gill histopathology was examined in three groups of parr of coho salmn (Oncorhynchus kisutch (Walbaum)) maintained for 30 days in suspended wood debris (< 1.00 mm diameter; concentrations of 44–132 mg/L dry weight) collected from an estuarine log sorting site. Gills of fishes were examined by light microscopy following exposure, and histopathologic responses were indexed by percentage of gill filaments affected. Lamellar edema and telangiectasis each had statistically significant (P < 0.05) associations with exposure to the suspended debris, and the severity of these conditions was positively correlated with increased concentrations of debris. The severity of hyperplasia of the primary filament epithelium did not correlate with the concentration of debris. The total number of gill lesions in each fish (sum of hyperplasia, telangiectasis, and edema) was positively correlated with the concentration of debris to which the fish were exposed, and negatively correlated with the percent weight increment (((final...
TL;DR: In this article, an X-ray microanalysis revealed severe morphological changes in gill epithelia and underlying tissue, and a pronounced accumulation of aluminium was detected on the gill surface of exposed specimens.
TL;DR: In this paper, the liver, kidney and gills were analyzed for cadmium, copper, zinc and metallothionein in Rainbow trout during four months at 5°C.
TL;DR: The toxicity assessment is based on the histochemical observations of mucous cells present in the epithelia of gill rakers and filaments of Colisa fasciatus, to provide a better understanding of the pathogenic effects of crude oil on the branchial mucous of a freshwater fish.
Abstract: In the maintenance of respiratory activity of the gills in fishes, mucus secretion is known to have an important function. Crude oils and their fractions enter the fish tissue by positive transfer via the gills thus the mucus cells of gill epithelia act as an obvious site of pathogenic interactions between the fish and the environment. Mucous cell hyperplasia is a general phenomenon associated with crude oil toxicity. Even though a large quantity of crude oil pollutes the freshwater environment annually, literatures on the pathogenic effect of oil pollutants on the branchial mucous cells of fishes are limited to the marine and estuarine species. This investigation has been undertaken to provide a better understanding of the pathogenic effects of crude oil on the branchial mucous of a freshwater fish, Colisa fasciatus. The toxicity assessment is based on the histochemical observations of mucous cells present in the epithelia of gill rakers and filaments.
TL;DR: Evidence is presented for differential sensitivity of taurine transporters in the non-gill epithelium to inhibition by alpha-amino acids in Mytilus edulis L.
Abstract: SUMMARY The uptake of amino acids by the non-gill epithelia of the mantle cavity of Mytilus edulis L. was studied and compared with uptake by the gills. Amino acid entry rates and the subsequent distribution of amino acids to the other tissues of the animals were studied using high-performance liquid chromatography and radiochemical techniques. Uptake via the non-gill epithelia lining the mantle cavity was separated from uptake via the gill by employing a preparation in which the gills were surgically removed. Amino acid uptake by such animals was compared with that of suitably sham-operated controls. In short-term experiments (up to 2h), transfer of substrate from the gills to other tissues of the animal is extremely limited. Amino acids taken up by the non-gill epithelia of the mantle cavity are rapidly transferred to deeper tissues. Roughly 25 % of alpha-amino acids enter the animal via the non-gill epithelia. Estimates of total epithelial surface area for the gills and non-gill mantle epithelium are compared with entry rates of amino acid substrates via the two routes. The apparent densities of carriers for alanine and cycloleucine per unit area of surface are approximately equal for these two substrates. The density of taurine carriers per unit area of non-gill epithelium is apparently significantly higher than their density per unit area of gill epithelium. Finally, evidence is presented for differential sensitivity of taurine transporters in the non-gill epithelium to inhibition by alpha-amino acids.
TL;DR: The gills of the European eel, Anguilla unguilla L. were analysed morphometrically and suggest that the major sites of gill vascular resistance lie at the level of the afferent lamellar arterioles and the secondary lamellae.
Abstract: The gills of the European eel, Anguilla unguilla L. were analysed morphometrically. Fresh (unfixed) gills and resin-replica casts of the branchial vascular system were examined. The total gill surface area was found to be proportional to (body mas)0-715 for fish of between 60 and 1 160 g. This relationship between gill surfxe area and body mass was maintained irrespective of a reduction in body mass produced by fasting. Vessel dimensions were obtained from the vascular casts. Calculations made using these values suggest that the major sites of gill vascular resistance lie at the level of the afferent lamellar arterioles and the secondary lamellae.
TL;DR: It is suggested that the differences between the two species serve primarily to facilitate oxygen uptake, reduce the tendency for the gills to become clogged, and aid in flushing of the branchial chamber in hypoxic waters with a very high particle content.
Abstract: Branchial complements, gill morphology, gill surface areas, gill volumes, branchial volumes, and branchial space of the stream-dwelling parastacid crayfish Astacopsis franklinii and the burrowing Parastacoides tasmanicus are compared. A reduction in gill number in Parastacoides results from the absence of pleurobranchiae on the fifth, sixth, and seventh thoracic segments and the extreme reduction of the pleurobranch on segment 8. There is a tendency for gill filaments to be longer in Parastacoides and the terminal spines on the filaments of the podobranchiae are longer, hooked rather than straight, and occur more frequently in this species. Most of the respiratory exchange area is provided by the podobranchiae. Linear regression equations (log transformed data) describing the allometric relationship between body size and gill area, gill volume, branchial volume, and branchial space are provided for both species. Parastacoides has a significantly greater size-related gill area and branchial volume than Astacopsis and, since there are no differences in gill volume, there is also a significant increase in branchial space. Much of this additional space appears to be created towards the posterior of the branchial chamber. The differences between the two species are interpreted as adaptations for the burrowing, amphibious life-style adopted by Parastacoides. We suggest that they serve primarily to facilitate oxygen uptake, reduce the tendency for the gills to become clogged, and aid in flushing of the branchial chamber in hypoxic waters with a very high particle content; they are seen as providing secondary benefits to assist survival during the often prolonged periods when the burrows lack free water.
TL;DR: It is deduced that the monogenean B. tai had three, possibly four, generations a year, estimated as 3-5 months in winter and as 2-3 months in spring through autumn.
Abstract: Occurrence of a gill monogenean Bivagina tai was monitored monthly on a single stock of red sea bream Pagrus major artificially spawned and cultured in a net cage. The monogenean was found from the fish stock all the time except for the first few months, significantly in greater numbers on the first gills than on the others. The infection fluctuated with seasons. There were three peaks of infection during the two-year study period. The O+ fish had the highest level of infection in winter, but the infection was modest in the next winter, suggesting the peak infection resulted from lowered resistance of the small fish to infection at low temperatures. A second and a third peak of infection were formed in May, when the fish was just one and two years from hatching; the rise of water temperature was probably responsible for the peak formation. From the seasonal changes in the development of B. tai, using the clamp number as an in-dicator, it is deduced that the monogenean had three, possibly four, generations a year. The life-span is estimated as 3-5 months in winter and as 2-3 months in spring through autumn.
TL;DR: A heterogenous growth pattern during early ontogenesis of the fish results in intraspecific variation in the gill dimensions which might have been influenced by the acquisition of the air-breathing mechanism in the post-larval stage, besides ecological factors.
Abstract: Gill area and other component parameters of Colisa fasciatus during early life were measured for fish larvae divided into two groups (a) exclusively aquatic and (b) bimodal breathers. Statistical analyses of the data in relation to body size yielded two significantly different straight lines (one for aquatic and other for bimodal breathers) for each parameter. Morphological examinations of gill arches indicated that an increase in the gill area was brought about mainly by an increase in the filament length. The higher slope value (2.41) of gill area in the aquatic phase than that in the bimodal phase (b= 0.80) is suggestive of a higher weight-specific metabolism in the younger larvae. A heterogenous growth pattern during early ontogenesis of the fish results in intraspecific variation in the gill dimensions which might have been influenced by the acquisition of the air-breathing mechanism in the post-larval stage, besides ecological factors.
TL;DR: Osmoregulation of gills was as effective as that of retina despite the direct exposure of the former to the surrounding seawater.
TL;DR: Variations in the gross morphology and surface architecture of the gill filaments and secondary lamellae of a freshwater catfish (Rita rita) have been investigated using scanning electron microscopy and correlated with their probable functions.
Abstract: Variations in the gross morphology and surface architecture of the gill filaments and secondary lamellae of a freshwater catfish (Rita rita) have been investigated using scanning electron microscopy. Heterogeneity of the gill has been correlated with the distribution of lamellar water-flow at different regions of a gill filament. Higher lamellar water flow (cc/pore/cmH2O/sec) was estimated for the middle region of the filaments. The filaments are covered with epithelial cells whose surface is provided with well-developed microridges. The lamellae are generally covered with microvillous epithelial cells. The variations in surface architecture of the gill filaments and secondary lamellae have been correlated with their probable functions.
TL;DR: Two specific characteristics, the number of secondary denticles on the claw of the maxilliped and theNumber of setae on the exopod of the first maxilla, distinguish females of Albionella from those of Lernaeopoda.
Abstract: Albionella fabricii n. sp. is described from the gills of the black dogfish Centroscyllium fabricii caught off the west coast of Newfoundland. Morphological differences are found in all the female and male appendages between Albionella fabricii n. sp. and A. centroscyllii, another species occurring concurrently on the same host. Female A. fabricii n. sp. can easily be distinguished from its four congeners by the length and structure of the second maxillae and the length of the uropods. A comparison between Albionella fabricii n. sp. and identifiable females of the genus Lernaeopoda is necessary, since both genera differ mainly in the morphology of the male. Two specific characteristics, the number of secondary denticles on the claw of the maxilliped and the number of setae on the exopod of the first maxilla, distinguish females of Albionella from those of Lernaeopoda.