Number Of Hemocytes Research Articles

The Influence ofPlagiorchis mutationisLarval Infection on the Cellular Immune Response of the Snail HostLymnaea stagnalis

The effects of trematode Plagiorchis mutationis parasitism on the cellular immune responses of the snail host Lymnaea stagnalis were investigated. The number of spreading blood cells (hemocytes) from infected snails was significantly less (69.5%) than in uninfected individuals (79.2%). The phagocytic activity of blood cells in infected snails was also significantly less (17.2%) compared to uninfected snails (27.8%). The hemocytes from the infected snails did not form a complete capsule around Sephadex beads in vitro. The protective reactions of the snail hosts were independent of the parasite load (daily cercariae production). In vitro, dead cercariae of P. mutationis were encapsulated by hemocytes from uninfected snails. The hemocytes of the infected snails formed a complete capsule around only 20% of dead cercariae in vitro, with remaining cercariae either unencapsulated (50% of cercariae) or incompletely encapsulated (30% of cercariae). The total number of hemocytes in the infected snails was twofold less than in uninfected individuals. The results of this study showed that the cellular response of snail host L. stagnalis to P. mutationis trematode infection is similar to the previously studied snail-trematode model systems.

Immune response ofChilo suppressalisWalker (Lepidoptera: Crambidae) larvae to different entomopathogenic fungi

The current study reports mortality and effects on cellular immune response of several entomopathogenic fungi including isoleates BB1, BB2 and BB3 of Beauveria bassiana, Metarhizium anisopliae, Isaria fumosoroseus and Lecanicilium lecanii against larvae of Chilo suppressalis. Prohemocytes, granulocytes, plasmatocytes and oenocytoids were identified as the main circulating hemocytes in the hemolymph of larvae using Giemsa staining solution. Entomopathogenic fungi caused differential mortality on larvae: BB1, BB3, M. anisopliae lead to the highest mortality on larvae and L. lecanii caused the lowest mortality. The highest numbers of total hemocytes were observed 3 h post-injection of B. bassiana isolates and 6 h for the other treatments. The highest numbers of plasmatocytes were observed 3 h post-injection of BB1 and Tween 80, whereas BB2, BB3, M. anisopliae, I. fumosoroseus and L. lecani caused plasmatocyte increase 6 h post-injection. Similar results were obtained in case of granulocytes but only Tween 80 showed the highest number of hemocytes 3 h post-injection. The highest numbers of nodules were found at various time intervals after injection of fungal isolates and latex bead. The highest activities of phenoloxidase were observed 12 h post-injection by BbB1, BbB3, M. anisopliae and latex bead; 3-6 h post-injection by BbB2, 6 h post-injection by I. fumosoroseus and 3-6 h post-injection by L. lecanii. Our data demonstrate the possibility of utilizing different fungal extracts in the field to help reduce the risk of resistance evolution in C. suppressalis and encourage experimentations aimed to increase the number of biological control agent for insect pests such as the striped rice stem borer C. suppressalis.

Responses of freshwater mussel (Elliptio complanata) hemocytes exposed in vitro to crude extracts of Microcystis aeruginosa and Lyngbya wollei

Lyngbya wollei is a benthic filamentous cyanobacterium that produces a toxin analogous to the neurotoxic saxitoxin known as lyngbyatoxin (LYNGTX). Microcystis aeruginosa form blooms in the pelagic area of eutrophic lakes and produce a series of potent hepatotoxins-microcystins (MCYST). The aim of this study in vitro study was to examine the difference between the crude extracts of either M. aeruginosa or L. wollei toward the immune system of Elliptio complanata mussels. Freshly isolated hemolymph was plated and exposed to the crude extract of each species at LYNGTX or MCYST equivalent concentrations of 5, 10 and 25μg/L for 18h. Immunocompetence was characterized by following changes in hemocyte numbers, metabolic activity (viability), and phagocytosis. Hemocyte counts were not affected, indicating no turnover of hemocytes. Hemocyte metabolic activity was higher in cells exposed to crude extracts of L. wollei. Exposure to L. wollei extracts led to decreased pro-inflammatory precursors such as reactive oxygen species (ROS) and cyclooxygenase (COX) activities. Phagocytosis increased at 25μg/L for both types of crude extracts. However, hemocytes exposed to crude extracts of M. aeruginosa produced more ROS and COX compared to hemocytes exposed to crude extracts of L. wollei. In conclusion, the data suggest that the crude extract of M. aeruginosa was more toxic than crude extract of L. wollei to mussel hemocytes.

Humoral and haemocytic responses of Litopenaeus vannamei to Cd exposure.

White shrimp, Litopenaeus vannamei, subadults were exposed to four dilutions of the 96 h cadmium LC50 reported for postlarvae (PL12) of this species, and the effects were evaluated after 5, 48, and 96 h of exposure. While treatments did not affect survival and hemolymph clotting time increased with time, but not as a response to Cd exposure, the intensity of other responses was related to concentration, to time of exposure, and to their interaction. Hemocyanin decreased with time in all metal concentrations but increased in the control treatment, and an almost similar trend was observed with hemocyte numbers. As an initial response, phenoloxidase activity decreased with all metal concentrations, but it increased later to values similar or higher than the control treatment.

Intense exercise increases protein oxidation in spleen and liver of mice.

Studies have indicated that sports anemia is mainly associated with intravascular hemolysis induced by exercise. We hypothesized that such exercise-induced hemolysis leads to oxidative damage due to an increase in free iron caused by hematocyte destruction. Thirty-one male ICR mice were randomly divided into 3 groups: a rested control group, an intense-exercise group, and a group rested for 24 hours after intense exercise. The serum haptoglobin level of the intense-exercise group decreased compared with that of the rested control group, suggesting hemolysis. Tissue iron and protein carbonyl levels in the liver were increased after exercise, and the protein carbonyl level in the spleen on the day after exercise was significantly increased compared with that of the resting state. These results suggest that the spleen and liver, where extravascular hemolysis occurs, were subjected to oxidative modification by the free iron, which was released from large numbers of hemocytes that were destroyed due to the intense exercise.

Exposure to the Neurotoxic Dinoflagellate, Alexandrium catenella, Induces Apoptosis of the Hemocytes of the Oyster, Crassostrea gigas

This study assessed the apoptotic process occurring in the hemocytes of the Pacific oyster, Crassostrea gigas, exposed to Alexandrium catenella, a paralytic shellfish toxins (PSTs) producer. Oysters were experimentally exposed during 48 h to the toxic algae. PSTs accumulation, the expression of 12 key apoptotic-related genes, as well as the variation of the number of hemocytes in apoptosis was measured at time intervals during the experiment. Results show a significant increase of the number of hemocytes in apoptosis after 29 h of exposure. Two pro-apoptotic genes (Bax and Bax-like) implicated in the mitochondrial pathway were significantly upregulated at 21 h followed by the overexpression of two caspase executor genes (caspase-3 and caspase-7) at 29 h, suggesting that the intrinsic pathway was activated. No modulation of the expression of genes implicated in the cell signaling Fas-Associated protein with Death Domain (FADD) and initiation-phase (caspase-2) was observed, suggesting that only the extrinsic pathway was not activated. Moreover, the clear time-dependent upregulation of five (Bcl2, BI-1, IAP1, IAP7B and Hsp70) inhibitors of apoptosis-related genes associated with the return to the initial number of hemocytes in apoptosis at 48 h of exposure suggests the involvement of strong regulatory mechanisms of apoptosis occurring in the hemocytes of the Pacific oyster.

Developmental changes in cellular and humoral responses of the burying beetle Nicrophorus vespilloides (Coleoptera, Silphidae)

Necrophagous beetles of the genus Nicrophorus have developed various defence mechanisms that reduce the negative effects of adverse environmental conditions. However, many physiological and ecological aspects, including the functioning of the immune system in burying beetles, are still unknown. In this study, we show developmental changes in cellular and humoral responses of larvae, pupae, and adults of Nicrophorus vespilloides. We assessed changes in total haemocyte count, phenoloxidase activity, and phagocytic ability of haemocytes. We found that during larval development there is a progressive increase in humoral and cellular activities, and these responses are correlated with alterations of total haemocyte counts in the haemolymph. In the pupal stage, a sharp drop in the number of phagocytic haemocytes and an increase in phenoloxidase activity were observed. In adults, cellular and humoral responses remained at a lower level. It is probable that high lytic activity of anal and oral secretions produced by parents supports a lower response of the immune system in the initial phase of larval development. In the studied stages, we also observed differences in polymerisation of F-actin cytoskeleton of haemocytes, number of haemocytes forming filopodia, and filopodia length. These results suggest that the differences in immune responses during various stages of development of N. vespilloides are associated with a dynamically changing environment and different risks of infection. For the first time a detailed analysis of stage-specific alterations in immune system activity during development of the burying beetle is presented.

Pesticide and Predation Exposure Effects on Pond Snail Immune System Function and Reproductive Output

ABSTRACT Malathion is an organophosphate pesticide that is sprayed agriculturally and for public health threats such as malaria and West Nile virus. It can contaminate surface waters, where it can interact with aquatic organisms. In addition to combating exposure to pesticides, aquatic organisms must defend against biotic stressors, which could intensify effects imparted by chemicals. We investigated effects that exposure to an environmentally relevant malathion concentration (0.001 µg/L) and predation cues imparted on immune system function and reproductive output in individuals in the pond snail species Lymnaea stagnalis (Linnaeus, 1758) (Gastropoda: Pulmonata). Snails were grown in four exposure treatment groups: nonmalathion— nonpredation, nonmalathion—predation, malathion—nonpredation, and malathion—predation. Malathion exposure caused a decrease in hemocyte numbers, which was unaffected by predation cue exposure, and a decrease in egg numbers, which was amplified by predation cue exposure. These res...

Non‐pathogenic aquatic bacteria activate the immune system and increase predation risk in damselfly larvae

SummaryPathogens can increase vulnerability to predation through their harmful effects on hosts. Recently, it was shown that the mere activation of the immune system by pathogens may increase the host's risk of predation. Here, we test whether exposure to non‐pathogenic bacteria also activates the immune system and thereby increases vulnerability to predation.We exposedEnallagma cyathigerumdamselfly larvae to a non‐pathogenic strain of the bacteriumEscherichia coliand measured immune defence, anti‐predator behaviour and survival times in the presence of larval dragonfly predators. To evaluate whether non‐pathogenic bacteria also generated energy‐based trade‐offs leading to other fitness costs, we also quantified growth rate and survival in the absence of predators.Exposure to the non‐pathogenic bacterium did not affect survival in the absence of the predator but increased growth rate, possibly a response to reduce exposure time to the bacterium. Larvae exposed to the bacterium activated their immune response as shown by an increase in the activity of phenoloxidase and the number of haemocytes. The bacterium affected anti‐predator traits involved in avoiding detection by predators as well as traits involved in escape after detection. Pre‐exposed larvae showed higher activity levels and further increased the number of feeding strikes in the presence of predation risk, possibly driven by energetic constraints. Pre‐exposed larvae swam less often when attacked, but faster. This impaired anti‐predator response came at the ecological cost of increased vulnerability to predation.Our study demonstrated that exposure to non‐pathogenic bacteria increases vulnerability to predation, which is a novel type of antagonistic interaction. This highlights the unexplored possibility that non‐pathogens may play a role in maintaining variation in immune defence through insidious effects on predator–prey interactions. Since non‐pathogenic bacteria can be very abundant, this unexplored ecological cost of immune system activation in terms of increased predation may have major consequences in natural systems and may provide an unexplored new force underlying variation in immune defence.

An increase in the immune system activity of the wax moth Galleria mellonella and of the Colorado potato beetle Leptinotarsa decemlineata under effect of organophosphorus insecticide

There has been performed evaluation of the effect of the organophosphorus insecticide (pirimifos-methyl) on some components of the insect immune response. The cellular (a change of the number of hemocytes and of intensity of incapsulation) and the humoral (a change of phenoloxidase activity) components of the immune response were studied in larvae of representatives of two orders--the Colorado potato beetle (Leptinotarsa decemlineata, Chrysomelidae, Coleoptera) and the wax moth (Galeriia mellonella, Pyralidae, Lepidoptera). The action of the insecticide has been found to lead to stimulation of immune reactions (an increase of phenoloxidase activities and of intensity of incapsulation, a rise of the number of hemocytes) at the contact treatment of both sublethal and the half-lethal doses of pirimifos-methyl.

Behavioural and immunological responses to an immune challenge in Octopus vulgaris

Behavioural and immunological changes consequent to stress and infection are largely unexplored in cephalopods, despite the wide employment of species such as Octopus vulgaris in studies that require their manipulation and prolonged maintenance in captivity. Here we explore O. vulgaris behavioural and immunological (i.e. haemocyte number and serum lysozyme activity) responses to an in vivo immune challenge with Escherichia coli lipopolysaccharides (LPS). Behavioural changes of immune-treated and sham-injected animals were observed in both sight-allowed and isolated conditions, i.e. visually interacting or not with a conspecific. Immune stimulation primarily caused a significant increase in the number of circulating haemocytes 4h after the treatment, while serum lysozyme activity showed a less clear response. However, the effect of LPS on the circulating haemocytes begins to vanish 24h after injection. Our observations indicate a significant change in behaviour consequent to LPS administration, with treated octopuses exhibiting a decrease of general activity pattern when kept in the isolated condition. A similar decrease was not observed in the sight-allowed condition, where we noticed a specific significant reduction only in the time spent to visually interact with the conspecific. Overall, significant, but lower, behavioural and immunological effects of injection were detected also in sham-injected animals, suggesting a non-trivial susceptibility to manipulation and haemolymph sampling. Our results gain importance in light of changes of the regulations for the use of cephalopods in scientific procedures that call for the prompt development of guidelines, covering many aspects of cephalopod provision, maintenance and welfare.

Cloning of prophenoloxidase from hemocytes of the blue crab, Callinectes sapidus and its expression and enzyme activity during the molt cycle

The arthropods cuticle undergoes dramatic morphological and biochemical changes from being soft to hardness through each molting process. Prophenoloxidase (PPO) known as a key enzyme in the arthropod innate immune system involved in the melanization reaction, has been related with the initial shell-hardening process, specifically in the sclerotization of the protein matrix in the new cuticle. Since hemocytes have been reported as the main PPO source in arthropods, the transport of hemocyte PPO into the newly laid, soft cuticle has been proposed for shell-hardening occurring during and immediately after ecdysis. In order to define the role of hemocyte PPO in the shell-hardening of crustaceans, the full-length cDNA sequence (2806 nt) of hemocytes PPO of the blue crab Callinectes sapidus (CasPPO-hemo) is isolated using degenerate PCR and 5′-3′ RACE. CasPPO-hemo encodes a putative PPO (672 aa) showing three hemocyanin domains: N, M, and C in order and two copper binding sites (CuA & CuB). The sequence analysis identifies the putative CasPPO-hemo as zymogen which requires the cleavage at the N-terminus for its activation. Hemocyte extract (CasHLS) contains the PO, the activity of which depends on the in vitro activation of trypsin. The expression levels of CasPPO-hemo are kept constant during the molt cycle. The increase in the number of hemocytes at early premolt correlates with the elevated PO activity, while at late premolt, the increment in hemocyte numbers does not reflect on the PO activity. The functional importance of the changes in the levels of CasHLS-PO activity during molt cycle is discussed in relation to cuticle hardening process.

Non-monotonous dose–response curves observed for some endpoints, after pre- and postnatal exposure of rats to the fungicide epoxiconazole

Astakine is considered as an endogenous cytokine-like factor of prokineticin homologue in invertebrate. Recently, an astakine homologue (CgAstakine) has been identified and characterized in oyster Crassostrea gigas. In the present study, a CgATP synthase β subunit was identified as the receptor of CgAstakine in C. gigas. There was an ATP-synt_ab_N domain and an AAA domain in the CgATP synthase β subunit protein. The mRNA transcripts of CgATP synthase β subunit were detected in all tested tissues, with the highest expression level in hepatopancreas and gills, which was 109.11-fold (p < 0.01) and 97.21-fold (p < 0.01) of that in labial palps, respectively. After rCgAstakine stimulation, the mRNA transcripts of CgATP synthase β subunit in agranulocytes and semi-granulocytes were significantly increased at 24 h (2.44-fold, and 9.01-fold of that in control group, p < 0.01), and those in granulocytes were significantly increased at 6 h (1.83-fold, p < 0.01), 12 h (1.92-fold, p < 0.01) and 24 h (3.47-fold, p < 0.01). The expression level of CgATP synthase β subunit protein in agranulocytes and granulocytes was also significantly increased after rCgAstakine stimulation, which was 1.64-fold (p < 0.05) and 1.85-fold (p < 0.05) of that in control group, respectively, while there were no significant changes in semi-granulocytes. The immunofluorescence assay showed that CgATP synthase β subunit positive signals were mainly located on the membrane of haemocytes. The number of haemocytes with EdU positive signals was significantly increased after rCgAstakine stimulation (2.04-fold of seawater group, p < 0.01), while significantly decreased after the RNA interference (RNAi) of CgATP synthase β subunit, which was 0.28-fold of that in NC group (p < 0.01). Bio-layer interferometry (BLI) assay confirmed in vitro interaction between rCgAstakine and rCgATP synthase β subunit. There results suggested that CgATP synthase β subunit acts as the receptor of CgAstakine and plays important roles in CgAstakine induced renewal of haemocytes in C. gigas.

Biological Responses of &lt;I&gt;Rhynchophorus ferrugineus&lt;/I&gt; (Coleoptera: Curculionidae) to &lt;I&gt;Steinernema carpocapsae&lt;/I&gt; (Nematoda: Steinernematidae)

Rhynchophorus ferrugineus (Olivier 1790) (Coleoptera: Curculionidae) is becoming a serious problem in Mediterranean areas where it is well-adapted, and now is present even in the United States (California). The infestations are primarily in urban areas where chemical control is not advisable and million of Euros are spent to control it. The effects of the entomopathogenic nematode Steinernema carpocapsae (Nematoda: Steinernematidae) on mortality, growth, as well as the immune activity of R. ferrugineus larvae, were investigated. R. ferrugineus mortality exhibited a positive trend with the dosage and duration of exposure to S. carpocapsae. The median lethal dose and median lethal time, important to optimize the treatments, were calculated. S. carpocapsae also had a detrimental effect on R. ferrugineus weight. In vivo and in vitro effects of S. carpocapsae on the phagocytic responses of R. ferrugineus hemocytes also were recorded. S. carpocapsae was not encapsulated by R.ferrugineus hemocytes. After 24 h, the number of hemocytes recorded in treated larvae was reduced. To investigate the defensive abilities of R. ferrugineus humoral and cellular immune systems, specifically against the bacterium Xenorhabdus nematophila (Enterobacteraceae), the minimum inhibitory concentration that inhibits bacterial growth was measured. This is the first time that this technique is applied to entomopathogenic bacteria.

A serine proteinase PmClipSP2 contributes to prophenoloxidase system and plays a protective role in shrimp defense by scavenging lipopolysaccharide

Serine proteinases (SPs) participate in various biological processes and play vital role in immunity. In this study, we investigated the function of PmClipSP2 from shrimp Penaeus monodon in defense against bacterial infection. PmClipSP2 was identified as a clip-domain SP and its mRNA increased in response to infection with Vibrio harveyi. PmClipSP2-knockdown shrimp displayed a significantly reduced phenoloxidase (PO) activity and increased susceptibility to V. harveyi infection. Injection of LPS and/or β-1,3-glucan induced a dose-dependent mortality and a significant decrease in the number of total hemocytes, with clear morphological changes in the hemocyte surface, of the PmClipSP2-knockdown shrimp. Recombinant PmClipSP2 was shown to bind to LPS and β-1,3-glucan and to activate PO activity. These results reveal that PmClipSP2 acts as a pattern-recognition protein, binding to microbial polysaccharides and likely activating the proPO system, whilst it may play an essential role in the hemocyte homeostasis by scavenging LPS and neutralizing its toxicity.

Administration of Hot Water Extract Diatomae Caetoceros Ceratosporum via Injection Enhances the Immune Resistance of White Shrimp Litopenaeus vannamei against Infectious Myonecrosis Virus

Immune resistance of white shrimp against disease can be enhanced through the administration of immunostimulant. Some of sea microalgae extracts has been proved trough examination to be able to stimulate immune system of shrimp. The objective of this study is to know immune response of Litopenaeus vannamei injected with hot water extract Chaetoceros ceratosporum (HWEC) doses of 5, 10, 15 and 20 µg·g -1 body weight (BW) against Infectious Myonecrosis (IMNV) virus infection. The findings show that C . ceratosphorum administration can enhance immune response of L. vannamei infected by Infectious Myonecrosis virus, indicated by the increasing number of hemocytes (THC), total protein plasma (TPP), phenolokxidase (PO) activity, and respiratory burst (RB) activity. Highest immune response is achieved by injection dose of 15 µg·g -1 shrimp body weight. The increase of shrimp immune response leads to the increase of shrimp immune system against IMNV infection, so the survival rate of L. vannamei infected by IMNV is higher than positive control and similar to those of negative control.

The Effects of Cadmium Exposure on the Oxidative State and Cell Death in the Gill of Freshwater Crab Sinopotamon henanense

We studied here the short-term toxicity effects of Cd on the oxidative state and cell death in the gill of freshwater crab Sinopotamon henanense. Crabs were exposed to Cd that resulted in Cd accumulation and a significant increase in the metallothionein (MT) level in the gill, but MT level increased disproportionally compared to the Cd accumulation with an extension of exposure time. Significant changes in the activities of superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) were observed. An increase in the levels of reactive oxygen species (ROS) and lipid peroxidation (LPO) was detected that will cause oxidative stress. Histological abnormalities of the gills were discovered, including the expansion of gill cavity, a decrease in the numbers of connection of the upper and the lower of the gill lamellae and epithelial cells, and an increase in the number of hemocytes. The results of a TUNEL test and transmission electron microscope (TEM) showed that more gill cells had apoptotic characteristics after 48 h of Cd treatment compared to the control, but epithelial cell necrosis and inflammatory response appeared only after 72 h. It was concluded that (1) Cd induced the ROS production and accumulation through inhibiting antioxidant enzyme activities and exceeding the saturation values of MT binging; (2) Cd led to lipid peroxidation and histopathological alternations; and (3) Cd induced apoptotic response at short time exposure, followed by necrotic features and inflammatory reaction after longer time exposure.

High larval density does not induce a prophylactic immune response in a butterfly

Immune function is greatly affected by biotic and abiotic factors, arguably owing to resource allocation trade‐offs. While starvation typically exerts negative effects on immune function, there are two competing hypotheses regarding the impact of population density: a high population density may decrease or increase immune competence, either as a result of reduced energy stores or of augmented resource allocation to minimise infection risk (density‐dependent prophylaxis). Against this background, the effects of population (= larval rearing) density and transient food stress on adult immune function and life‐history traits in the temperate‐zone butterfly Pieris napi (Linnaeus) have been examined. Both a period of larval starvation and high larval rearing density prolonged the development time and reduced the body mass. All immune parameters measured (pro‐phenoloxidase and phenoloxidase activity, haemocyte number, encapsulation rate) were also negatively affected by high density, whereas starvation had no effect. We thus found no evidence for density‐dependent prophylaxis, but a diminished performance at a high density probably caused by reduced energy stores. The present study reinforces that the maintenance and deployment of an efficient immune system is costly, which may prohibit prophylactic responses to high population densities.

Spatial and temporal in vivo analysis of circulating and sessile immune cells in mosquitoes: hemocyte mitosis following infection

BackgroundMosquitoes respond to infection by mounting immune responses. The primary regulators of these immune responses are cells called hemocytes, which kill pathogens via phagocytosis and via the production of soluble antimicrobial factors. Mosquito hemocytes are circulated throughout the hemocoel (body cavity) by the swift flow of hemolymph (blood), and data show that some hemocytes also exist as sessile cells that are attached to tissues. The purpose of this study was to create a quantitative physical map of hemocyte distribution in the mosquito, Anopheles gambiae, and to describe the cellular immune response in an organismal context.ResultsUsing correlative imaging methods we found that the number of hemocytes in a mosquito decreases with age, but that regardless of age, approximately 75% of the hemocytes occur in circulation and 25% occur as sessile cells. Infection induces an increase in the number of hemocytes, and tubulin and nuclear staining showed that this increase is primarily due to mitosis and, more specifically, autonomous cell division, by circulating granulocytes. The majority of sessile hemocytes are present on the abdominal wall, although significant numbers of hemocytes are also present in the thorax, head, and several of the appendages. Within the abdominal wall, the areas of highest hemocyte density are the periostial regions (regions surrounding the valves of the heart, or ostia), which are ideal locations for pathogen capture as these are areas of high hemolymph flow.ConclusionsThese data describe the spatial and temporal distribution of mosquito hemocytes, and map the cellular response to infection throughout the hemocoel.

English

Shells of crabs are infected with a high prevalence&nbsp;of diseases&nbsp;than any other crustacean. Bacteria, viruses, fungi and several other pathogens influence higher percentage of shell disease in crabs. Infections in crab affected&nbsp;growth and metabolism and it may also lead to death. This work deals with the microscopic examination of shell diseased crabs with reference to its variation in hemocytes count, histopathology and biochemical estimation. The total heterotrophic bacterial (THB) population in normal shell was found to be 5.15 x 104&nbsp;&plusmn; 0.09 Colony forming unit (CFU)&nbsp;ml-1&nbsp;and THB load was noted to be slightly increased than in normal shell and the count was 5.95 x 104&nbsp;&plusmn;&nbsp;0.12&nbsp; CFU ml-1&nbsp;in the infected shell. The current findings suggest a positive correlation between bacterial shell disease and the secondary infection affecting hemolymph (total hemocyte count), proximate composition (protein,&nbsp;carbohydrate and lipid) and histopathology of the animal (gills, hepatopancreas and heart). The total hemocyte count and differential count were experimented which showed lower number of total hemocytes in infected crabs while no highly accountable difference was found in differential count. Hematology studies reported total hemocyte as 9.93 x106&nbsp;&plusmn; 0.07 cells ml-1&nbsp;in normal and 6.525 x 106&nbsp;&plusmn; 0.12 cells ml-1in shell diseased hemolymph. The level of protein, carbohydrate and lipid contents suffered a mild alteration in crabs with bacterial shell disease. Histopathology of gills&nbsp;hadshown variations such as dilated lamellae and hemocyte accumulation (nodules), hepatopancreas showed mild difference with increased necrosis, appearance of hemocytic nodules in the hemal spaces and heart with very mere infection while no reportable changes were accomplished in muscle tissue. &nbsp; Key words:&nbsp;Shell disease, bacteria, hematology, histopathology, biochemical composition.