Secondary Lamellae Research Articles

Histopathological Assessment of Infested Farmed Clarias Gariepinus at Various Developmental Stages in Different Culture Management System

ABSTRACT: Parasitic infections infringe on different organs causing varying degrees of histological changes which contribute directly or indirectly to fish loss. Histological alterations play significant implication in fish health thereby proffer supports for effective diagnoses to improve the management of cultured fish. Various developmental stages of farmed Clarias gariepinus were randomly collected from 100 farms across the three agricultural zones (East, West and Far – East) in Lagos State, Nigeria from purposively classified culture systems based on water usage management systems (WUMS) into daily water renewal (DWR), weekly water renewal (WWR) and bi – weekly water renewal (BWR)). The organs (skin, gills and intestines) were selected for parasitological examinations and histological sectioning using standard procedure. The water qualities monitored were temperature, dissolved oxygen, pH, ammonia, nitrite, iron, alkalinity, hardness and turbidity and measured using standard methods. Descriptive statistics such as frequency count, percentages, standard deviation were used to determine the occurrence and rate of histological changes in relations with parasitic infections while semi-quantitative analysis was used to assess the histological lesion on gills. This study reveals possible relationship between parasitic infections and histological changes on the gills. The protozoans (Trichodina sp, Vorticella sp., Tetrahymena sp., Chilodonella sp., Piscinoodinium sp. and Ichthyobodo sp.) and monogenean trematode (Dactylogyrus sp., and Gyrodactylus sp.) were related parasites found with varying degrees of histological changes like hyperplasia of the epithelial cells, lifting of the primary epithelium, sloughing of the epithelium, fusion of the secondary lamellae, oedema of the lamellae, vacuolation of the epithelial cells, swelling of the epithelial cells, diffuse infiltration of lamina propria by neutrophil and necrosis of the secondary lamellae, classified into stages I, II and III. The most frequently observed histopathology in all the culture systems was hyperplasia of the gill lamellae; DWR-86.96%, WWR – 88.1%, BWR – 92.86%, followed by the fusion of the secondary lamellae; DWR-65.22%, WWR–75%, BWR– 78.57%. No histopathological change was observed on the skin and the intestine and lesions were least in the daily water renewal (DWR) culture system. Hence, it can be safely inferred that good management practice in terms of water renewal system should be encouraged to alleviate parasitic infections and minimize organ damage in cultured fish.

Histological changes in Horabagrus brachysoma acclimated to warm temperature and exposed to critical thermal maxima and minima

Escalating concerns about global climate change necessitate investigations into its consequences for the survival of poikilothermic animals like fish. The present study describes histological alterations in gill, skin, kidney, liver, and brain tissues of the juvenile Horabagrus brachysoma specimens acclimated to 26°C (control) and 36°C for 30 days, and those exposed to dynamic temperature changes (increased or decreased at the rate of 0.3°C/min from 26°C), the critical thermal maxima (CTMax) and critical thermal minima (CTMin). The fish acclimated to 36°C and those exposed to CTMax (40.23 ± 0.12°C) and CTMin (14.15 ± 0.10°C) showed severe histological aberrations in gill, skin, liver, kidney, and brain tissues. Histological alterations in gill tissues included loss of epithelial cells in the branchial arch, thinning of the primary lamellae, and loss of the secondary lamellae. Thickening of the epithelial layer (36°C), and desquamation of epithelial cells (CTMax) were the histological alterations detected in skin tissues. Alterations in liver tissues included severe congestion with vacuolization and the cloudy appearance of cells and extensive loss of cellular contour. Extensive vacuolization with complete flattening of the tubule epithelial cells, distorted appearance of tubular lamellae, and marked loss of glomerular tuft were the changes recorded in kidney tissues. Brain tissue alterations comprised increased cellularity and vacuolization in the cerebrum (36°C), and nodular masses of various sizes in the cerebrum (CTMin). The present study showed that acclimation to warm temperature (36°C) and exposure to dynamic temperature changes (CTMax and CTMin) cause histopathological alterations in the vital organs of H. brachysoma. The findings of the present study can help in monitoring the health of H. brachysoma in the natural environment and in culture systems under a climate change scenario.

Morphological and genotoxic analysis of fish of the Okhchuchay River in Zangilan District

In July 2022, monitoring of the transboundary Okhchuchay River was carried out from the borders with Armenia deep into the Zangilan District of Azerbaijan. The Okhchuchay River is playing the role of an industrial waste collector, as it is constantly polluted with waste from the Kafan and Gajaran mining industries in Armenia. From the five monitoring points studied, only two specimens of Oxynoemacheilus brandtii were caught. For morphological and genotoxic studies, samples of peripheral blood, liver, and gills were taken. The analysis showed that in the gills of Oxynoemacheilus brandtii, hyperplasia of the interlamellar epithelium and respiratory epithelium of secondary lamellae, complete fusion of secondary lamellae, uneven distribution of hyperplasia of secondary lamellae, and detachment of the respiratory epithelium were detected. Expansion of sinusoids, melanomacrophage centers, and necrotic changes were revealed in the liver. When examining the blood, among the changes in the structure of the nucleus of erythrocytes, karyolysis, karyorrhexis, deformation of the nucleus, parietal nuclei, eccentric nuclei, and hemoglobin breakdown were observed. The obtained data confirm the catastrophic ecological state of the Okhchuchay basin.

Oxidative Stress Potential, Genotoxic and Histopathological Effects of Ethanolic Extract of Alternanthera philoxeroides on Clarias gariepinus (Cat Fish)

This study used static bioassay to evaluate oxidative and genotoxic effect caused by ethanolic extract of A. philoxeroides in the liver of C. gariepinus as well as the Histopathological damages caused by the extract on the liver, gills and intestine of the fish. LC50 of the ethanolic extract of A. philoxeroides was determined by probit regression analysis. Fishes were exposed to the sublethal concentration of the extract at the rate of 1% and 10% concentration of the LC50 value in replicate for 21days. During the cause of exposure the fishes exhibited some behavioral changes such as erratic swimming pattern, restlessness and excessive mucus secretion. The oxidative stress study revealed that antioxidant enzyme activities were lower in the liver suggesting deficiency of the antioxidant system to compensate for oxidative stress. DNA damage was high in liver of the exposed fish indicating genotoxic effects. The histological structure of the liver of the fish showed the presence of traces to mild onset of nuclei degeneration. The gills of fish exposed to the extract showed severe collapse of the secondary lamella in conjunction with hyperplasia of the pillar cells within the lamella as well as severe atrophy of the cells, degeneration of the primary lamella and severe cellular and structural damages of the gills. The intestine of the fish group exposed to the extract revealed a small amount of PAS-positively stained substances in the lamina propria, mucus cells and the apical borders of the epithelial cells showing the presence of mucous substances. This study concluded that exposure of C. gariepinus to ethanolic extract of Alternanthera philoxeroides have the ability to negatively affect the behavior, suppress the activities of major antioxidant enzymes of the liver thereby causing oxidative stress, with consequent degeneration of liver and gill tissue which expresses its genotoxicity.

The Babylon River's common carp (Cyprinus carpio) gills were used for the histopathological examination and PCR detection of Koi herpesvirus disease (KHVD)

The first outbreak of koi herpesvirus in Iraq occurred in Babylon Province in the floating cages in the Euphrates River from the Musayyib thermal electric power station to the Al-Hindiya Dam. Fish were suffering from gills rot that did not respond to treatment and lesions and ulcers on the fish's body. The fatalities reached 80%. was water temperature 24°C, pH 6.85, Salinity 760 ppt. So the present study aims to highlight the pathological changes in gills after the Koi herpes virus infection in Babylon Province. The study started after the detection of (KHV) by polymerase chain reaction ( PCR) from the suspected samples (30 ) for the detection of virus nucleic acid. Also, study the water characterization during the periods of outbreaks. The gills specimen was collected from the positive cases for gross and histopathological examination. The result showed that ten samples were positive for (KHV) infection. The gross and histopathological examination results showed severe congestion with necrotic foci and sloughing of secondary lamella with increased mucus secretion. In addition, necrosis in the primary lamellae, Edam and inflammatory cells infiltration with hyperplasia of the secondary lamellae with the presence of intranuclear inclusion body in all exanimated slides. Keywords: Koi Herpes; Cyprinus Carpio; Euphrates River; KHV; secondary lamellae; floating cages

Hematologi dan Histopatologi Insang Ikan Lele Hasil Budidaya Pembudidaya Lokal di Noekele, Kabupaten Kupang Timur

The aim of this study was to determine the haematological and histopathological of the Catfish gills cultured in Noekele, East Kupang, East Nusa Tenggara. The fish samples used were catfish taken randomly as many as 80 individuals from the rearing pond owned by local farmers in Noekele, then taken to the laboratory for measurement of length and weight, morphological abnormalities observation, preparation of fish blood smears and collection of gills for histological preparation. The observation of morphological abnormalities showed body lesion (90%), one ventral fins (31.3%), one pectoral fins (28.8%), dull and pale body colors (100%). Erythrocyte cell damage on haematological observation on blood smear were tear drop shaped, fusion, lacerated membrane, nuclear extrusion, blebbed nuclei, sperocytes (deformed cells), lysis and shrinking erythrocytes. Based on histopathological analysis, gill’s damage were secondary lamella edema, primary lamella vacuoles, secondary lamella necrosis, epithelium lifting, secondary lamella fusion. Loss of lamella structure, hyperplasia and presence of parasites.

Role of microstructure heterogeneity on deformation behaviour in additive manufactured Ti-6Al-4V

The influence of two different bi-lamellar microstructures, with varied volume fractions of primary alpha lamellae (αp) and secondary alpha lamellae (αs), on the mechanical performance of laser powder bed fusion fabricated Ti-6Al-4V has been investigated. A low and high αp volume fraction variant was created by different solution heat treatment temperatures. Scanning transmission electron microscopy (STEM) was performed on both materials to give a comprehensive assessment of the local microstructure and element partitioning effects. Deformation experiments, combined with high resolution digital image correlation (HRDIC), enabled a detailed comparison of 2D slip patterns at progressive strain increments during tensile loading, with the underlying microstructure collected using electron backscattering diffraction based grain orientation mapping. In both microstrural variants, shear strain was mainly observed in the coarse αp lamellae, suggesting that the constituent was softer than the fine αs regions. This strength difference is not attributed to potential different levels of Al-based solid solution strengthening as a result of element partitioning. Instead, the strength difference was attributed to the fine β ligaments formed in-between the αs during ageing. The low αp volume fraction variant, i.e. high-volume fraction of αs, displayed a significant increase in yield strength compared to the high αp volume fraction variant without compromising ductility through increased heterogeneous plasticity and an enhanced strain hardening rate.

Environmental factors can affect the relationship between Nile tilapia and its parasites in cage systems culture

Parasites represent a serious obstacle in Brazilian intensive fish farming, and then, monitoring parasitic infestations in aquaculture is a duty of every tilapia producer. The objective of this study was to identify the branchial ectoparasites of Nile tilapia, evaluate the correlation between parasitic intensity, host biometrics, and limnological variables, as well as to identify gill histological changes in fish. Thus, fish representing the three phases (I, II, and III) of production were collected in two commercial fish farms - 1 and 2, necropsied, and their parasites quantified and identified. The gill alterations were processed for histological analysis. Cichlidogyrus sclerosus and Scutogyrus longicornis (Monogenoidea), and Lamproglena monodi (Lernaeidae) have been identified in the tilapia gills. The highest intensities of Monogenoidea infestation were in summer and autumn in both fish farms, with a positive correlation between parasites and water temperature. Infestation by L. monodi occurred only in Fish farm 2, with greater infestations in winter and spring, with a negative correlation between water temperature and parasitism. There was also an increase in parasitism according to the weight and length of the fish in the two fish farms. Histological changes such as hyperplasia, lamellar hypertrophy, and the presence of basophilic cysts on the secondary lamellae were detected in tilapia. Thus, water quality parameters and season of the year, which are closely related, can affect communities of parasites that infest Nile tilapia grown in cages. These findings are important to assist in planning disease control and prevention strategies for Nile tilapia fish farming, to reduce economic losses resulting from fish diseases and death.

Toxicological effects of the textile industrial effluent to an Indian freshwater fish, Clarias batrachus

In this study, the histological effects of textile industrial effluent in the freshwater fish, Clarias batrachus was studied after 10, 20, and 30 days period of exposure. The 24, 48, 72, and 96 hours LC50 values were found to be 58.476, 53.231, 47.253, and 37.429% respectively. During the experiment, the treated fishes showed abnormal behaviors like erratic swimming, hyper-excitation, rapid opercular movement, and thick mucus covering which indicated the toxicity of the effluent. The observed changes in the gills were epithelial hyperplasia with lamellar fusion, necrosis, vacuolar degeneration, and atrophy of primary and secondary gill lamellae. On the other hand, the liver showed the formation of the number of vacuoles, enlargement of nuclei of some cells, degeneration of cytoplasm in hepatocytes, atrophy, a rupture in blood vessels, and disposition of hepatic cords. The kidney also showed abnormalities like degeneration of proximal and distal convoluted tubule, vacuolation of renal interstitial tissue, necrosis, cellular hypertrophy, and granular cytoplasm.

Black gill disease in Litopenaeus vannamei made by various agents

Melanization of shrimp gills is a general symptom in shrimp black bill diseases (sBG); therefore, the cause is not immediately apparent. This study aimed to determine the primary and secondary agents associated with a black gill outbreak in the Delvar complex in the Bushehr Province of Iran. During July and August of 2020, 450 healthy and affected shrimps were collected based on brown to black gill color from three farms of the Bushehr Province in Iran. Characterization of pathogens was performed by gross signs, wet mounts, microbiological tests, histopathology methods, and sequencing of molecular markers. The mean weight and length of infected shrimps was significantly (P < 0.05) lower than the healthy shrimps. The histological examination of sBG indicated the adhesion of secondary lamellae, accumulation of hemocyte cells at the end of the secondary lamellae, and necrosis of epithelial cells with pyknosis and karyorrhexis. According to our results, Aspergillus sydowii as a primary agent correlates with sBG disease in Litopenaeus vannamei from Iran, and other biotic factors, including bacterial (Vibrio owensii and V. parahaemolyticus) probably are secondary agents associated with sBG disease.

Fish Gills as a Tool for the Assessment of Sublethal Effects of Monocrotophos on a Freshwater Fish, Etroplus maculatus

Agricultural pesticides are nowadays being extensively used for the control of a wide variety of agriculturalpests. The world over, human health is at risk. While on one hand people are dying due to scarcity of food,on the other they are slowly being poisoned by the chemicals used for growing food. Other than targetedpests, pesticides affect a wide range of non-target organisms, such as invertebrates and fin fish inhabitingaquatic environment. The present laboratory study is aimed at assessing the sublethal effects ofmonocrotophos on the gills of Etroplus maculatus, a fresh water food fish as well as an indigenous ornamentalfish of the paddy fields of Kuttanad, the rice bowl of Kerala. Sublethal exposure was done in a static systemand the target organ undergoes histological Hematoxylin-eosin staining procedures. The pathologicalchanges were obviously dose–dependent and maximum severity was noticed in the gills of fishes exposedto the highest sublethal concentrations. The overall changes observed due to the exposure to differentconcentrations of monocrotophos are hypertrophy, hyperplasia, fusion of secondary lamellae, oedematousseparation of respiratory epithelium, lamellar telangiectasis, stasis, filamental blood vessel enlargementand necrosis. Based on the histological lesions observed the index values were calculated. On the basis ofthe index values, No Observable Effect Concentration (NOEC), Least Observable Effect Concentration(LOEC) and Maximum Allowable Toxicant Concentrations (MATC) of monocrotophos to E. maculates werecalculated. The concentration which showed index value less than 10 is taken as NOEC and between 10-20is taken as LOEC. MATC of monocrotophos to E. maculates is estimated as 0.4243 ppm. Based on the MATCthe calculated application factor (AF) was 0.1263. These NOEC, LOEC, MATC and AF so obtained for thisspecies can also be used to assess tentative water quality status for the pollutants in the natural environment,and the AF derived from the laboratory studies can be directly applied to the filed situations, as they are therepresentative sample of Kuttanad. Histopathology is an important biomonitoring tool for the farmers indeciding the concentrations of pesticides before its application into the paddy fields.

Oxidative Stress Biomarkers Activities and Histological Changes in African Catfish (Clarias gariepinus) Exposed to Carwash Wastewater

The study evaluated the acute toxicity of vehicle wastewater on African catfish (Clarias gariepinus). With a weight range of 250–275.5g and a mean length of 23.5-28.5cm, 150 post-juvenile catfish were purchased from Dalar Kifi Fish Farm BUK New site road, Kano State, and acclimated in a tank for 14 days. Fish were exposed to different vehicle wastewater concentrations of 0.0, 20, 40, 60, and 80% v/v with 5-level exposure concentrations during the acute test (96 hours) in a Completely Randomized Design (CRD) employing renewal bioassay. The acute bioassay showed that the LC50 for the wastewater was 56 percent by volume at 96 hours. Compared to the control, the exposed fish exhibited abnormal swimming, erratic opercular movement, reflex loss, mucus secretion, increased air gulping with an increase in wastewater concentration. Except for water temperature, Biochemical Oxygen Demand (BOD) and pH, the remaining physicochemical parameters were not within the WHO/FAO recommended Standard The order of concentrations of the heavy metal in the wastewater was Cu &gt; Pb &gt; Cd &gt; Cr &gt; Ni. Antioxidant biomarker activities showed that Glutathione reductase (GSH) reduced in the same manner while Catalase (CAT) and Superoxide dismutase (SOD) activities rose considerably (P&lt;0.05) in the liver and gill tissues. Histopathological changes observed in gill tissues were as follows: Hyperplasia, necrosis, primary and secondary lamellae distortion, and epithelial thickening distortion. Hepatic cell breakdown, fatty degeneration, cellular infiltration, localized fibrosis, and cellular necrosis were all visible in the liver tissues. It can be inferred that changes in the histology and activity of the oxidative stress enzymes in fish tissues after exposure to wastewater harmed the experimental fish. As a result of their effects on fish and other non-target aquatic biotas, it is advised that the competent authorities create initiatives to reduce the indiscriminate discharge of untreated vehicle wash wastewater.

Differential sensitivity of offspring from four species of goodeine freshwater fish to acute exposure to nitrates

Nitrate-nitrogen (NO3-N) pollution related to anthropogenic activities is increasing in freshwater ecosystems. Knowledge about NO3-N sensitivity in freshwater wild fish is needed to understand the differential tolerance between species. Goodeinae is a subfamily of 41 endemic fishes that inhabit central Mexico, with 33 species in the IUCN red list and three extinct. Distributional patterns suggest tolerant and sensitive goodeines related to the conservation gradient of freshwater ecosystems. Four species with a differential distribution and tolerance were selected to evaluate their physiological responses to NO3-N. Fish were exposed to different NO3-N concentrations for 96 h and the median lethal concentration (LC50) was determined. Swimming disorders plus gill and liver histopathological indexes were estimated and incorporated into an Integrated Biomarker Response (IBR) for each species. Skiffia lermae (LC50 = 474.332 mg/L) and Xenotoca variata (LC50 = 520.273 mg/L) were more sensitive than Goodea atripinnis (LC50 = 953.049 mg/L) and Alloophorus robustus (LC50 = 1537.13 mg/L). The typical histological damage produced by NaNO3-N exposure was fusion of secondary lamellae in gills. This was present in all species and cellular degeneration was observed at the highest concentrations. Secondary lamellae aneurysms were only observed in G. atripinnis. Liver alterations included vascular dilation in hepatic sinusoids, hyperemia and nuclear hypertrophy; higher concentrations produced hepatocyte cytoplasmic vacuolation and reduced frequency of cell nuclei. Behavioral and histopathological alterations could explain the differential species sensitivity. The results suggest that species which preserve gill function and transfer the task of detoxification to the liver might have the best chance of surviving in polluted environments. Moreover, species previously considered as tolerant may be highly susceptible to NaNO3-N exposure. Therefore, it is necessary to closely monitor NaNO3-N concentrations in freshwater ecosystems and, if possible, reduce their levels to avoid the loss of wild populations.

Prevalence of fish Parasites IN Bagrus bayad and Protopterus annectens from Upper River Benue in Mutum Biu, Taraba State, Nigeria

The prevalence of fish parasites in Bagrus bayad and Protopterus annectens from Upper River Benue in Mutum Biu, Taraba State, Nigeria was carried out using standard parasitological method. The objectives of this study were to investigate the parasite species spectrum, prevalence of each parasites species, overall prevalence, prevalence of parasite infection in relation to the size and sexes of Bagrus bayad and Protopterus annectens and the infection induced by parasites on/in their body parts, with the view of providing relevant information that can be used in combating the rate of economic losses that could be experienced as a result of parasitic infestations. 4 parasite taxa comprising of Twelve (12) parasite species (Trichodina spp., Henneguya spp. Cryptobia iubilans, Diphillobothrium latum, Hymenolepis nanna and Bothriocephalus aengypticus, Capillaria philipinensis, Caenorhabditis briggsae, Camallanus spp., Eustrongylides spp., Contracaecum spp. and Clinostomum spp. were recovered from the samples of fish species used during the study period. Twelve (12) of the parasite species were recovered from Bagrus bayad while seven (7) were recovered from Protopterus annectens. Among the body parts of Bagrus bayad, while intestine had the highest percentage parasite load (56.37%), highest percentage parasite load (46.22%) in Protopterus annectens was recorded for stomach (46.22%). Out of the 400 fish samples comprising of 200 each of Bagrus bayad and Protopterus annectens, 234 (58.50%) comprising of 99 (49.50%) and 135 (67.50%) samples each of Bagrus bayad and Protopterus annectens were infested with 369 and 119 parasites, respectively. However, there was no significant difference in the prevalence of infection and parasite load between the fish species, respectively (P&gt;0.05). Generally, larger sized samples of Bagrus bayad and Protopterus annectens had higher percentage of infection compared to the smaller sized of both samples although, the prevalence of infection in relation to sizes of both fish species was not statistically significant (P&gt;0.05). Female Bagrus bayad and Protopterus annectens had higher prevalence of infection (21.61%) and (16.63%) than the males (6.37%) and (6.24%), respectively. There was no significant difference in the prevalence of infection in relation to the sexes of both fish species (P&gt;0.05). Epidermal necrosis of the caudal fin and skin, thickened intestinal epithelium at the site of parasite attachment, hyperplasia of the intestinal villi and lamina propria, hyperplasia of infected gills at the secondary lamellae, ulceration of the stomach, abdominal distention, eroded and flattened intestinal folds and lymphocytic infiltration of intestinal mucosa and edema of the lamina propria of the intestine were observed with the infected samples of B. bayad. The infected samples of P. annectens exhibited epidermal necrosis of the skin.

Palliative role of colloidal silver nanoparticles synthetized by moringa against Saprolegnia spp. infection in Nile Tilapia: Biochemical, immuno-antioxidant response, gene expression, and histopathological investigation

Our study proposed a promising anti-fungal therapy to control Saprolegnia spp. infection in Nile tilapia (Oreochromis niloticus). A Moringa oleifera synthesized silver nanoparticles (MS-AgNPs) showed an in vitro anti-fungal activity against Saprolegnia spp. with an inhibition zone of 18 mm. A total of 220 O. niloticus (45 ± 0.56 g) were used in this study. A preliminary investigation was conducted by using 100 fish for determining the safe dose of MS-AgNPs which was found to be 0.6 mg/L. Another 120 fish were divided into four groups; the first (control) and second groups (G1 and G2) were non-infected and exposed to 0 and 0.6 mg/L MS-AgNPs, respectively. The third and fourth groups (G3 and G4) were infected with Saprolegnia spp. (1.5 × 104 spores/L) and exposed to 0 and 0.6 mg/L MS-AgNPs, respectively. The experiment lasted for 7 days. The infection with Saprolegnia spp. induced immunosuppression expressed by a marked decrease in immunoglobulin M, nitric oxide, complement 3, and lysozyme activity, with a 41 % survival rate. Additionally, a marked decline in the values of hepatic and branchial antioxidant enzymes (superoxide dismutase and catalase) in addition to serum total antioxidant capacity and protein profile indices. In contrast, Saprolegnia spp. infection elevated hepatic and branchial malondialdehyde, hepatic function indicators, and stress biomarkers (cholesterol and triglyceride) with up-regulation of the pro-inflammatory cytokines (IL-1ß and TNF-α), and the anti-inflammatory cytokines (IL-10 and TGF-β). Histopathological findings of the gills and musculature of infected fish showed severe hyperplasia of the epithelial lining with a fusion of secondary lamellae and necrotic myocytes admixed with edema. Interestingly, treatment of the challenged fish with MS-AgNPs at a dose of 0.6 mg/L could improve these variables by enhancing the histological architecture. According to these findings, MS-AgNPs have an ameliorative effect against the harmful effects of Saprolegnia spp. infection on immune-antioxidant status and hepatic functions indices. Consequently, MS-AgNPs at a dose of 0.6 mg/L is a promising option for use in the control of Saprolegnia spp. infection in aquaculture.

The differences of viscoelastic properties between the secondary wall S2 layer and compound middle lamella of thermally treated wood

The differences of viscoelastic properties between the secondary wall S2 layer and compound middle lamella of thermally treated wood

Acute and Chronic Toxicity Effects of the Heptachlor Pesticide on Tilapia (Oreochromis mossambicus): Impact to Behavioral Patterns and Histopathological Responses

Manimekalai, D.; Srinivasan, A.; Padmavathy, P.; Jawahar, P.; George, R., and Arisekar, U., 2022. Acute and chronic toxicity effects of the heptachlor pesticide on tilapia (Oreochromis mossambicus): Impact to behavioral patterns and histopathological responses. Journal of Coastal Research, 38(5), 999–1010. Coconut Creek (Florida), ISSN 0749-0208. Heptachlor is an organochlorine (cyclodiene) insecticide that enters water bodies and affects aquatic organisms such as fishes and shellfishes. Due to its persistent nature, it spreads from the source of its use and pollutes the area. The toxic effect of heptachlor on histopathological changes in the gill, liver, kidney, and muscles of tilapia Oreochromis mossambicus were studied. The experimental fish were exposed to four concentrations of heptachlor, viz., 0.756, 1.513, 3.025, and 6.050 ppm, for a period of 96 hours during an acute toxicity test. In the current study, the lethal concentration (LC50) value of heptachlor on tilapia at 96 hours was calculated as 4.006 ppm. Fish were subjected to three different concentrations of heptachlor (0.2003, 0.4006, and 0.8012 ppm) based on the LC50 value to study the long-term effect of heptachlor. Histological changes such as lamellar fusion, lamellar cell hyperplasia, degenerated secondary gill lamellae; Bowman's space dilation and renal tubules detachment; hepatic cells death, melanomacrophage formation, and multifocal degeneration of myocytes; and myoepithelium vacuolation were observed in the gill, kidney, liver, and muscles, respectively, during acute and chronic exposure to heptachlor. The toxicity study revealed that the heptachlor pesticide is highly toxic to tilapia even at a minimum concentration of 0.756 ppm. Hence, it is suggested that care must be taken not to allow the entry of pesticides into the habitat of fishes.

Toxic Effects of Arsenic in Commercially Important Fish Rohu Carp, Labeo rohita of Bangladesh

This study was designed to elucidate the effects of arsenic (As) on the morpho-behavior, growth development and molecular mechanisms of a commercially important fish, rohu carp, Labeo rohita, in Bangladesh. Fish fry with an average weight of 387.5 ± 169.25 mg and an average length of 3.35 ± 0.37 cm were collected from a local hatchery in Mymensingh, Bangladesh and acclimatized for a week in the Department of Fisheries, University of Dhaka before starting the exposure with arsenic. Fishes were exposed for a period of 14 days with three treatments of NaAsO2, namely treatment 1(T1)—2.5 mg/L; treatment 2 (T2)—15 mg/L; and treatment 3 (T3)—30 mg/L, along with a control (C)—0.0 mg/L, with three replicates. These concentrations were determined based on the LC50 value for 96 h measured for this experiment. This study revealed remarkable morphological abnormalities and deformities in arsenic-exposed rohu carp. In fish exposed to 30 mg/L, caudal fin erosion was a frequent deformity. There was no significant difference in RNA:DNA ratio among the treatments. The overall weight of fish was decreased as the concentration of arsenic was increased. The T3 fish had a statistically significant negative weight gain (−0.05 ± 0.07 g), but the other treatments (T1 and T2) and control fish had no significant weight gain. Different types of histopathological changes were observed in the gills and intestines of arsenic-treated fish. Necrosis and severe damages were found in the secondary lamellae of gills at the highest arsenic concentration (30 mg/L). Epithelial lifting, irregular shape and damages in the gill raker were also observed in the primary lamellae of the gills for the same treatment. In this study, the expression of heat shock protein (HSP 60) and metallothionein (MT) genes was assessed by qPCR, and these genes were upregulated in different treatments compared to controls. The findings of the present study suggest that arsenic pollution significantly changes the morphology, behavior, growth, development, histopathology and molecular mechanisms of this economically important fish, rohu carp, in Bangladesh.

Closing cones create conical lamellae in secondary osteonal bone.

Lamellae are sheets of mineralized collagen 1–20 µm thick, extending over hundreds of µm in bone tissue, occupying bone's structural hierarchy at a level above collagen fibres and osteocytes, and below osteons and trabeculae. Osteons are tubular arrangements of lamellae surrounding central neurovascular canals. Lamellae in osteons are usually described as concentric cylinders based on their annular appearance in transverse section. In this review, I provide a perspective on current understanding of the relationship between geometry of the bone formation front and the shape of lamellae produced at it, reaching the conclusion that the ‘closing cone’ bone formation front in secondary osteonal remodelling must necessarily result in cone-shaped lamellae in the mature secondary osteon. Secondary osteons replace primary osteons through a tunnelling process of bone turnover, meaning that conical lamellae may become more common in older and damaged bone which is at greatest risk of fracture. Visualization and measurement of three-dimensional lamellar shape over hundreds of microns is needed to provide data for accurate micromechanical simulations. Treating secondary osteonal lamellae as a ‘stack of cones’ rather than ‘nested cylinders’ may have important implications for our appreciation of bone's function as a load-bearing tissue and of its behaviour in fracture.

Antioxidant enzyme activity and pathophysiological responses in the freshwater walking catfish, Clarias batrachus Linn under sub-chronic and chronic exposures to the neonicotinoid, Thiamethoxam®.

The hydrophilic nature and resultant persistence of neonicotinoids in aquatic systems increase the exposure duration for non-target organisms. The sublethal toxicity of the neonicotinoid Thiamethoxam® spanning sub-chronic and chronic durations was investigated in Clarias batrachus, a non-target freshwater fish species. 96 h LC50 value of Thiamethoxam® on Clarias batrachus was 138.60 mg L-1. Pre-determined exposure concentrations of Thiamethoxam® (6.93 and 13.86 mg L-1) were used and effects were assessed at days 15, 30, and 45 exposure intervals. Biomarker effects were evaluated using antioxidant enzyme responses (CAT, SOD) neurotransmission (acetylcholinesterase activity), haematological and serum biochemistry changes (including haemoglobin content, total erythrocyte count, and serum albumin total leukocyte count, total serum protein, serum globulin, triglyceride, cholesterol, high-density lipoprotein, very low-density lipoprotein, low-density lipoprotein, phospholipid, and total serum glucose), histopathological alterations (gill and liver). Thiamethoxam®-exposed fish showed a marked reduction in haemoglobin content, total erythrocyte count, and serum albumin levels compared to control fish. Similarly, gill and liver antioxidant enzyme activity (CAT, SOD) and neurotransmission (acetylcholinesterase) also showed altered responses between sub-chronic exposure on day-15 and chronic responses on day-45. Histopathological observations in gill tissue revealed alterations ranging from vacuolation, hypertrophy, disruption of primary lamellar architecture, haemorrhage, the fusion of secondary lamella, and sloughing of outer epithelia. For liver tissue of exposed fish histopathological observations included increased sinusoidal spaces (ISS), necrosis of hepatocytes (NOH), nuclear degeneration (ND), disruption of architecture (DOA), macrophage infiltration of the central vein, vacuolation (V), hypertrophied hepatocytes, and haemorrhages. The gradients of toxic responses across exposure concentrations and depictions of impaired fish health with increasing thiamethoxam® exposure duration portend lowered physiological capacity for survival in the wild.