Differential Expression of Hypothalamic and Gill-crh System With Osmotic Stress in the Euryhaline Black Porgy, Acanthopagrus schlegelii

The local gill production of corticotropin releasing hormone (crh) and crh-receptor (crhr) is hypothesized to play important roles during seawater (SW) and freshwater (FW) acclimation in euryhaline black porgy (Acanthopagrus schlegelii). The mRNA expression of crh, crhr, and Na+/K+-ATPase (a-nka) was examined in SW and FW diencephalon (Dien) and in the gills at different exposure time by Q-PCR analysis. The in situ hybridization results indicate that crh mRNA hybridization signals were more abundant in FW fish in the gigantocellular (PMgc) and parvocellular (PMpc) part of the magnocellular preoptic nucleus versus SW fish. The crh and crhr-expressing cells were located in basal cells of gill filament. Furthermore, in vitro dexamethasone (DEX) treatment could increase the crh-system in the gill. Increased transcripts of the crh-system in the gill via in vitro and in vivo CRH treatments suggest that CRH may regulate the system in a local manner. The a-Nka cells were localized in the filament and secondary lamellae mitochondria rich cells (MRCs) of FW fish at 8 h and 1 day. a-Nka cells were seen in both filament and lamellae in the FW but much less in SW fish indicating that gills play key roles in black porgy osmoregulation. Gill crh and crhr play important roles in the response to salinity stress.

Synchrotron CT of an equine digit at the Australian Synchrotron Imaging and Medical Beamline

Laminitis is an extremely painful and debilitating condition of horses that can affect their athletic ability and even quality of life. The current gold standard for assessment of laminar tissue is histology, which is the only modality that enables detailed visualization of the lamina. Histology requires dissection of the hoof and therefore can only represent one specific time point. The superior spatial and contrast resolution of synchrotron computed tomography (sCT), when compared with readily available imaging modalities, such as radiographs and conventional CT, provides an opportunity for detailed studies of the lamina without the need for hoof dissection and histological assessment. If the resolution of histology can be matched or even approached, dynamic events, such as laminar blood flow, could also be studied on the microscopic tissue level. To investigate this possible application of sCT further, two objectives are presented: (i) to develop a protocol for sCT of an equine digit using cadaver limbs and (ii) to apply the imaging protocol established during (i) for sCT imaging of the vasculature within the foot using an ex vivo perfusion system to deliver the vascular contrast. The hypotheses were that sCT would allow sufficient resolution for detailed visualization to the level of the secondary lamellae and associated capillaries within the equine digit. Synchrotron CT enabled good visualization of the primary lamellae (average length 3.6 mm) and the ex vivo perfusion system was able to deliver vascular contrast agent to the vessels of the lamina. The individual secondary lamellae (average length 0.142 mm) could not be seen in detail, although differentiation between primary and secondary lamellae was achieved. This approaches, but does not yet reach, the current gold standard, histology, for assessment of the lamellae; however, with further refinement of this imaging technique, improved resolution may be accomplished in future studies.

Histopathological Effects and Micronucleus Assay of Glyphosate-Based Herbicides on Cultured African Catfish (Clarias Gariepinus, Burchell 1822)

Background: Glyphosate, a brand of agricultural herbicides which intensive use has led to widespread contamination of different ecosystems. This study was designed to determine both organotoxicity and genotoxicity of glyphosate on African Catfish (Clarias gariepinus) exposed to different concentrations for 96 hours.Methods: Questionnaires were administered (physically and online) to determine the type of glyphosate-based herbicides mostly used by fish farmers. Seventy-five apparently healthy adult Clarias gariepinus (300g) were sourced from a local farmer, transported in a plastic keg to Fish and Wildlife Laboratory at the Department of Veterinary Public Health and Preventive medicine for two (2) weeks of acclimatization. After acclimatization, they were further divided into four (4) groups (T0 (Control), T1 (0.003ml/L), T2 (0.0045ml/L) and T3 (0.006ml/L)) by simple randomization and each group replicated into three (3) treatments. At the expiration of 96 hours of exposure, blood samples and organs (Gills, Kidney, and Liver) were collected for mononuclear assay and histopathological lesions respectively.Results: Exposed groups showed erratic swimming, splashing, and restlessness. Mortalities rate was dose-dependent (two (2) mortalities at 0.0045ml/L concentration (T2) and five (5) mortalities 0.006ml/L concentration (T3)). Observed histopathological lesions occurred at higher dose treatment (0.0045ml/L (T2) and (0.006ml/L) T3)) concentrations. The gills showed diffuse stunted and eroded secondary lamellae and severe congestion of the blood channel at the core of the primary lamellae. Lesions in the Liver include severe diffuse vacuolation of the hepatocytes, moderate to severe portal congestion and mild diffuse vacuolation of hepatocytes and moderate diffuse vacuolation of hepatocytes, and severe portal congestion. In the kidney, there was mild to moderate congestion of the interstitium and focus of interstitial oedema within the parenchyma. There was presence of micronucleus in the fish nucleated red blood cells at higher dose concentrations.Conclusion: This study showed that Glyphosate-based herbicides are highly toxic to Clarias gariepinus, therefore their use near the fish farm or in areas close to the aquatic environment should be discouraged. The agricultural community should also be conscious of the potentially adverse effects of pesticides. This is to prevent the water body from the residue of herbicides that would have washed down to the water.

Histopathological effects and micronucleus assay of glyphosate-based herbicides on cultured african catfish (Clarias Gariepinus, Burchell 1822)

Glyphosate, a brand of agricultural herbicides which intensive use has led to widespread contamination of different ecosystems. This study was designed to determine both organotoxicity and genotoxicity of glyphosate on African Catfish (Clarias gariepinus) exposed to different concentrations for 96 hours. Questionnaires were administered (physically and online) to determine the type of glyphosate-based herbicides mostly used by fish farmers. Seventy-five apparently healthy adult Clarias gariepinus (300g) were sourced from a local farmer, transported in a plastic keg to Fish and Wildlife Laboratory at the Department of Veterinary Public Health and Preventive medicine for two (2) weeks of acclimatization. After acclimatization, they were further divided into four (4) groups (T0 (Control), T1 (0.003ml/L), T2 (0.0045ml/L) and T3 (0.006ml/L)) by simple randomization and each group replicated into three (3) treatments. At the expiration of 96 hours of exposure, blood samples and organs (Gills, Kidney, and Liver) were collected for mononuclear assay and histopathological lesions respectively.Exposed groups showed erratic swimming, splashing, and restlessness. Mortalities rate was dose-dependent (two (2) mortalities at 0.0045ml/L concentration (T2) and five (5) mortalities 0.006ml/L concentration (T3)). Observed histopathological lesions occurred at higher dose treatment (0.0045ml/L (T2) and (0.006ml/L) T3)) concentrations. The gills showed diffuse stunted and eroded secondary lamellae and severe congestion of the blood channel at the core of the primary lamellae. Lesions in the Liver include severe diffuse vacuolation of the hepatocytes, moderate to severe portal congestion and mild diffuse vacuolation of hepatocytes and moderate diffuse vacuolation of hepatocytes, and severe portal congestion. In the kidney, there was mild to moderate congestion of the interstitium and focus of interstitial oedema within the parenchyma. There was presence of micronucleus in the fish nucleated red blood cells at higher dose concentrations.This study showed that Glyphosate-based herbicides are highly toxic to Clarias gariepinus, therefore their use near the fish farm or in areas close to the aquatic environment should be discouraged. The agricultural community should also be conscious of the potentially adverse effects of pesticides. This is to prevent the water body from the residue of herbicides that would have washed down to the water.

Histopathological changes in gills and liver of Clarias gariepinus fingerlings exposed to acute concentrations of dry cell battery

Waste dry cell batteries are frequently improperly disposed and subsequently washed into water bodies-- causing deleterious effects on fish particularly Clarias gariepinus which inhabits diverse freshwater habitats. Acute toxicity of water-soluble fractions of waste dry cell batteries was investigated on C. gariepinus fingerlings under laboratory conditions in 96 hours. Ten (10) C. gariepinus fingerlings were exposed to acute concentrations (0.31, 0.63, 1.25, 2.50, and 5.00 g/L) of waste dry cell batteries and a control (0.00 g/L), each duplicate replicated. Histopathological alterations evident in the gills were lamellar fusion, hyperplasia, inter-lamella space occlusion, hypertrophy and erosion of secondary lamellae. The liver showed nuclear and hepatocytes degeneration, vacuolation and portal congestion. Acute concentrations of water-soluble fractions of waste dry cell batteries caused significant (P<0.05) changes in the histomorphology of the gills and liver of C. gariepinus fingerlings, therefore indiscriminate disposal of waste dry cell batteries around riparian ecosystem should be safeguarded to reduce the declining diversity and abundance of freshwater fish species. Keywords: African catfish, 96 hr.LC50, Fingerlings, Histopathology Zinc-carbon battery

Histopathological alterations caused by monogenean parasites the gills of tambaqui Colossoma macropomum (Serrasalmidae)

Monogeneans are ectoparasites of fish with a global distribution. In farmed fish, high infestations may result in morbidity and mortality. This study investigated the histopathological effects of three species of monogeneans Anacanthorus spathulatus, Notozothecium janauachensis and Mymarothecium boegeri on the gills of farmed Colossoma macropomum. Parasitological indices revealed a prevalence of 100%, and a mean abundance of 81.3 ± 11.8. This infection caused displacement of the gill epithelium, focal hyperplasia of epithelial cells, lamellar fusion, congestion and shortening of the secondary lamellae of gills, in addition a complete fusion of the secondary lamellae. However, these tissue alterations were reversible and punctually located lesions, which may not compromise the normal functioning of gills. Lastly, this study showed the potential damages caused by parasite monogeneans to gills of infested fish, thus sanitary management is essential for the growth of fish farm of C. macropomum.

Histopathological alterations in gills, kidney and liver of Nile Tilapia (Oreochromis niloticus) fingerlings exposed to aqueous leaf extract of Desert Date (Balanites aegyptiaca)

One of the many biomarkers for determining the effects of pollutants on fish is changes in organ histopathology. Leaves of Balanites aegyptiaca have been reported to have phytochemicals with fish anaesthetic property. This study sought to determine the effect of graded acute concentrations (200.00, 250.00, 300.00.350.00 and 400.00 mg/L) of B. aegyptiaca on histopathology of gills, kidney and liver of mixed sex of Oreochromis niloticus fingerlings. A total of 120 O. niloticus fingerlings (mean weight 23±0.03 g and mean total length 12.50±0.39 cm) were exposed to the plant extract. Paraffin wax method and haematoxylin-eosin staining techniques of tissue processing were adopted for the examination of the gills, kidney and liver. Dose-dependent histopathological changes were observed in the three organs (gills, kidney and liver) i.e. histopathological alterations increase with increase in concentration of the plant extract. Gills showed lamellae fusion, haemorrhage, desquamation, atrophy and secondary lamellae erosion while kidney and liver indicated atrophy, necrosis, haemorrhage, hyperplasia and hypertrophy. Structural alterations were evident in the gills, kidney and liver of O. niloticus fingerlings exposed to the concentrations of aqueous crude leaf extract of B. aegyptiaca therefore it should be used with caution during fish anaesthesia. Keywords: Histopathology; Gill; Kidney; Liver; Balanites aegyptiaca; Oreochromis niloticus.

Ontogenic Development Of Gills In Pre To Post-Flexion Stages Larvae Of Himalayan Snow Trout Schizothorax Plagiostomus (Heckel)

The ontogenic development of gills, including gill arch, gill filaments, and gill rakers in pre to postflexion stages larvae of Himalayan Snow Trout Schizothorax plagiostomus were studied with the objectives that this study could serve as a base for further studies about the early embryonic development and organogenesis in various fish species inhabiting hill stream environments. To obtain the pre to post-flexion stages larvae, an artificial breeding experiment was conducted during September- October on the bank of snow-fed river Alaknanda by stripping method. Further, the development of the gill apparatus was studied histologically, using light microscopy. Hatchling takes place 124-130 hours after fertilization at the incubation temperature of 19-200C. On second dph (day post-hatching), gill arches, gill filaments, and branchiostegal membrane began to differentiate. By the third dph, blood channels were observed in gill filaments as well as in pseudobranch. Formation of secondary lamellae, branchial arteries, elongation of the gill cover, cartilaginous rod formation in the gill arch, and the branchiostegal membrane was discernible by fourth-fifth dph. Pillar cells and afferent and efferent arteries with RBCs in primary and secondary lamellae were observed on the seventh dph. Around the onset of exclusive exogenous feeding (twelfth dph), gill rakers and a group of pillar cells with blood channels were recognizable. Well-organized and functional gill structures with increased number and size of secondary gill lamellae were present among the fifteenth-seventeenth dph larvae. The general pattern of structural and functional development of both the natural site and laboratory-reared larvae was similar, except a large amount of mucous and clustered epithelial cells among the laboratory-reared larvae, which may be due to the physiological as well as environmental stress posed by the adverse physicochemical conditions.

Assessment of oxidative DNA damage, oxidative stress responses and histopathological alterations in gill and liver tissues of Oncorhynchus mykiss treated with linuron

We investigated changes in 8-hydroxy-2-deoxyguanosine (8-OHdG) activity which is a product of oxidative DNA damage, histopathological changes and antioxidant responses in liver and gill tissues of rainbow trout, following a 21-day exposure to three different concentrations of linuron (30 µg/L, 120 µg/L and 240 µg/L). Our results indicated that linuron concentrations caused an increase in LPO levels of liver and gill tissues ( p < 0.05). While linuron induced both increases and decreases in GSH levels and SOD activity, CAT activity was decreased by all concentrations of linuron ( p < 0.05). The immunopositivity of 8-OHdG was detected in the hepatocytes of liver and in the epithelial and chloride cells of the secondary lamellae of the gill tissues. Our results suggested that linuron could cause oxidative DNA damage by causing an increase in 8-OHdG activity in tissues, and it induces histopathological damage and alterations in the antioxidant parameters of the tissues.

Morpho-Functional Alterations in the Gills of a Seawater Teleost, the Ornate Wrasse (Thalassoma pavo L.), after Short-Term Exposure to Chlorpyrifos

Chlorpyrifos (CPF) is an organophosphorus insecticide commonly used for domestic and agricultural purposes. The risk posed by environmental contamination from CPF is well acknowledged, and it has been detected worldwide in aquatic habitats and coastal areas. In addition, due to its slower degradation in seawater compared to freshwater, CPF is of particular concern for marine environments. Here, we investigated for the first time the morpho-functional alterations induced by CPF on the gills of Thalassoma pavo, a widespread species in the Mediterranean Sea. We tested the effects of two sublethal concentrations (4 and 8 µg/L) after 48 and 96 h. Our study demonstrates that the alterations induced by CPF are dose and time-dependent and highlight the harmful properties of this insecticide. After exposure to the low tested concentration, the more frequent alteration is an intense proliferation of the primary epithelium, whereas after exposure to the high concentration, the primary epithelium proliferation is less extensive, and the most evident effects are the thinning of secondary lamellae and the ectopia of chloride and goblet cells. CPF also modulated the expression of Na+/K+-ATPase. Dilation of lamellar apical tips, pillar cell degeneration, and appearance of aneurysms are often observed.