Host response in the white shrimp, Penaeus setiferus, to infection by the larval trypanorhynchid cestode, Prochristianella penaei

White shrimp, Penaeus setiferus, infected by the plerocercoid larva of the trypanorhynchid cestode, Prochristianella penaei, respond to infections in the heptaopancreas by developing a progressively denser cyst, composed of hemocytes, fibroblasts, and collagenlike fibers, around the parasite. The pleocercoid is eventually destroyed and resorbed leaving a dense fibrous capsule in the hepatopancreas. Worms in the adjacent hemocoel are encapsulated by a thin host cyst and a less intense infiltration of cells and deposition of fibers, insufficient to destroy the pleroceroid. It is believed that the resorption process explains the drop in intensity of infection in juvenile white shrimp after a certain size is attained.     

Characterization of Scale Abnormalities in Pinfish, Lagodon rhomboides, from Biscayne Bay, Florida

Correlations between marine habitat degradation and the prevalence of abnormalities and diseases in populations can provide a starting point for understanding the effects of changes in environmental conditions on marine organisms. The present study characterized the features of scale disorientation (SD), a common morphological anomaly encountered in pinfish, Lagodon rhomboides, in Biscayne Bay, Florida (U.S.A.). Scale disorientation consisted of discrete patches of scales rotated dorsally or ventrally away from the normal scale position without any projection of the scales outwards from the body surface. The direction of scale growth within the patches varied from normal to a minor misalignment to a complete reversal of direction. The severity of SD, defined as the percentage of body surface area affected, varied from 1 to 34% with a mean of 9.3%. Affected fish monitored in the laboratory demonstrated a proportional growth of SD areas such that the percentage of body surface affected did not change as the fish grew. Scale disorientation was more prevalent in the northern region of the bay, an area known to be more contaminated. Scales from SD areas exhibited significantly abnormal morphology with larger average focus diameter, smaller size, more elongate shape and fewer radii relative to normal scales. Experimental removal of scales demonstrated that normal scales regrew in normal orientation and morphology while those from SD areas regrew in abnormal orientations and morphologies. Experiments in which fish were exposed to acute and chronic injuries indicated that these physical traumas were insufficient to directly induce formation of scale disorientations typical of those seen in the wild. Observations of pinfish in the laboratory revealed that SD areas can appear spontaneously in normal juvenile and adult fish. These new SD areas developed relatively rapidly, did not require prior scale loss and remained stable in size after first appearance. Although the etiology of SD remains unknown, the significant difference in prevalence of this syndrome between regions of Biscayne Bay having different levels of sediment contaminants suggests that environmental factors may be important in development of SD.     

A major developmental defect observed in several Biscayne Bay,Florida, fish species

Synopsis Stunted or missing dorsal spines or rays, sometimes accompanied by a depression in the dorsal profile, were found in 10 fish species in six families from North Biscayne Bay. The same morphological abnormality occurred inHaemulon sciurus, H. parrai, H. plumieri, Lagodon rhomboides, Archosargus rhomboidalis, Diplodus argenteus, Lutjanus griseus, Kyphosus sectatrix, Sphoeroides testudineus, andLactrophyrys quadricornis. Another morphological abnormality, scale disorientation, was found in six species:H. parrai, L. rhomboides, A. rhomboidalis, L. griseus, andAbudefduf saxatilis. Pugheadedness, jaw deformities, and other abnormalities also were observed. The occurrence of similar deformities across such a spectrum of fishes from the same location suggests the deformity was induced by something in the environment common to all these species. Although there could be other explanations for the unusual cluster of abnormalities, it is suspected that the same environmental contaminant or group of contaminants is adversely affecting a common developmental pathway of these fishes. Biscayne Bay is an urban estuary that receives agricultural, industrial, and residential run off.     

Ecology and distribution of diatoms in Biscayne Bay,Florida (USA): Implications for bioassessment and paleoenvironmental studies

The spatial and temporal distribution of planktonic, sediment-associated and epiphytic diatoms among 58 sites in Biscayne Bay, Florida was examined in order to identify diatom taxa indicative of different salinity and water quality conditions, geographic locations and habitat types. Assessments were made in contrasting wet and dry seasons in order to develop robust assessment models for salinity and water quality for this region. We found that diatom assemblages differed between nearshore and offshore locations, especially during the wet season when salinity and nutrient gradients were steepest. In the dry season, habitat structure was primary determinant of diatom assemblage composition. Among a suite of physicochemical variables, water depth and sediment total phosphorus (STP) were most strongly associated with diatom assemblage composition in the dry season, while salinity and water total phosphorus (TP) were more important in the wet season. We used indicator species analysis (ISA) to identify taxa that were most abundant and frequent at nearshore and offshore locations, in planktonic, epiphytic and benthic habitats and in contrasting salinity and water quality regimes. Because surface water concentrations of salts, total phosphorus, nitrogen (TN) and organic carbon (TOC) are partly controlled by water management in this region, diatom-based models were produced to infer these variables in modern and retrospective assessments of management-driven changes. Weighted averaging (WA) and weighted averaging partial least squares (WA-PLS) regressions produced reliable estimates of salinity, TP, TN and TOC from diatoms (r² = 0.92, 0.77, 0.77 and 0.71, respectively). Because of their sensitivity to salinity, nutrient and TOC concentrations diatom assemblages should be useful in developing protective nutrient criteria for estuaries and coastal waters of Florida.     

Experiments on the growth of Penaeus vannamei Boone

Growth rates of Penaeus vannamei Boone were estimated from field and laboratory experiments using both marked and unmarked shrimp. Field results with unmarked shrimp indicated growth rates of between 0.05 mm increase in carapace length per day (mm c.l./day) and 0.17 mm c.l./day, although rates of up to 0.31 mm c.l./day were also recorded. Moult intervals ranged from5.5 to 34 days with a mean of 12.5 days. Moult increment ranged from 0.2 mm c.l./moult to 1.4 mm c.l./moult with an overall mean of 0.7 mm/moult. Growth was negatively correlated with size over all size ranges, with a marked decrease in growth rate occurring at about 28 mm c.l. Shrimp marked with Floy streamer tags generally grew more slowly than unmarked shrimp, but this was exaggerated by the stress of regular handling in some experiments. The relevance of these findings is discussed in relation to the existing commercial fishery.     

Pathophysiology of cestode infections: Effect of Hymenolepis diminuta on oxygen tensions,pH and gastrointestinal function

Studies on the normal and parasitized rat intestine were used to investigate the effect of the tapeworm, Hymenolepis diminuta, on in vivo intestinal lumenal oxygen tensions, acid-base balance and mucosal absorption and accumulation of fluid and glucose.The lumenal bulk aqueous phase is considerable, well mixed and aerobic with an oxygen tension of 40–50 mm Hg. Neither the unstirred layers adjacent to the brush border membrane nor the area adjacent to the mucosa (“paramucosal lumen”) are significant barriers to the diffusion of oxygen from the blood to the intestinal lumen. In the uninfected distal ileum and colon anoxic conditions may occur in the central lumen, but, in the parasitized intestine fluid absorption is reduced and anoxic conditions do not occur. Increased H⁺ ion concentration in the parasitized intestine plays a role in increasing the availability of oxygen to intestinal helminths. Concomitant with the lower pH, the pCO₂ in the lumen of the parasitized intestine was twice as high as that found in normal animals. The total CO₂ in the parasitized intestine steadily decreased over a 3-h perfusion period, while in the normal intestine the total CO₂ content increased after an initial fall during the first 30 min of perfusion. When the worms were removed, the ability of the intestine to restore normal acid-base balance was restored. Glucose and fluid absorption in both the infected and uninfected intestine were reduced by an increase in H⁺ ion concentration; both parameters were lower in the parasitized intestine than in the normal animals. Low pH increased fluid and glucose transport by H. diminuta.While the dry weights of both the parasitized and uninfected total small intestine and of the intestinal mucosa were the same, the wet weights were considerably different, indicating defective fluid balance in the infected intestine. Accumulation of glucose by the parasitized mucosa was greater than in control animals and decreased with an increase in H⁺ ion concentration. The glucose transport system in the parasitized gut was therefore affected at two levels, one at the brush border, where transport into the mucosa was decreased by lowering the pH, and secondly at the level of the basal and lateral membranes, where transport out of the mucosal tissue into the circulatory system was also reduced.The above results are discussed in terms of current widely accepted but erroneous concepts relating to the intestinal ‘microcosm’.     

LIDAR optical rugosity of coral reefs in Biscayne National Park,Florida

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Ro_tran), and the average elevation difference between adjacent points (Av(E_ap)). Further, the whole-site mean and maximum values of Ro_tran and Av(E_ap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs.     

Assimilation efficiency of zinc and cadmium in the decapod crustacean Penaeus indicus

The assimilation of trace metals from food can be the main route of metal uptake into aquatic invertebrates. The assimilation efficiencies of zinc and cadmium from muscle tissue of a cephalopod mollusc (40% to 70% Zn, 64% to 83% Cd) and from a macrophytic alga (50% to 69% Zn, 39% to 50% Cd) were measured in juvenile penaeid prawns Penaeus indicus. Assimilated Zn and Cd were retained mostly in the hepatopancreas of the prawns, some metal being excreted (Zn k_e 0.10 and 0.11 and Cd k_e 0.004 and 0.009, from cephalopod muscle and alga, respectively). There were no significant differences between k_es (efflux rate constants) of one metal from either diet. Given the high trace metal assimilation efficiencies measured here, it is highly probable that metal assimilation from food plays an important role in Zn and Cd accumulation in the body of P. indicus, particularly in estuarine stages of the life cycle, for estuaries are particularly prone to metal pollution and are likely to offer the prawns abundant metal-rich diets such as detrital material derived from local macrophytes.     

Tissue specificities of Thelohania duorara,Agmasoma penaei, and Pleistophora sp., microsporidian parasites of pink shrimp, Penaeus duorarum

The pathology of pink shrimp, Penaeus duorarum, infected with the microsporidians Thelohania duorara, Agmasoma penaei, and Pleistophora sp. was described. Infections of T. duorara were widespread in most tissues; spores were located throughout the hemocoel, at the periphery of all striated muscle bundles, and in muscle and connective tissue surrounding the digestive tract. A. penaei infections invaded only dorsal abdominal muscles, muscles adjacent to blood vessels, and ovaries. Infected muscles and ovaries were eventually completely destroyed. Masses of A. penaei spores were often engulfed by hemocytes. Pleistophora sp. infected the interior of all striated muscles. Infected muscles were never completely destroyed but were often atrophied.     

Diversity of the cassiicolin gene in Corynespora cassiicola and relation with the pathogenicity in Hevea brasiliensis

Corynespora cassiicola is an important plant pathogenic Ascomycete causing the damaging Corynespora Leaf Fall (CLF) disease in rubber tree (Hevea brasiliensis). A small secreted glycoprotein named cassiicolin was previously described as an important effector of C. cassiicola. In this study, the diversity of the cassiicolin-encoding gene was analysed in C. cassiicola isolates sampled from various hosts and geographical origins. A cassiicolin gene was detected in 47 % of the isolates, encoding up to six distinct protein isoforms. In three isolates, two gene variants encoding cassiicolin isoforms Cas2 and Cas6 were found in the same isolate. A phylogenetic tree based on four combined loci and elucidating the diversity of the whole collection was strongly structured by the toxin class, as defined by the cassiicolin isoform. The isolates carrying the Cas1 gene (toxin class Cas1), all grouped in the same highly supported clade, were found the most aggressive on two rubber tree cultivars. Some isolates in which no Cas gene was detected could nevertheless generate moderate symptoms, suggesting the existence of other yet uncharacterized effectors. This study provides a useful base for future studies of C. cassiicola population biology and epidemiological surveys in various host plants.     

Molecular and biological characterization of molt-inhibiting hormone of Penaeus monodon

The action of molt-inhibiting hormone (MIH) on the inhibition of ecdysone release from the Y-organ of decapod crustacean keeps the animal in the intermolt stage that dominates its molting cycle. MIH is thus one of the major keys in mediating growth and reproduction. This study has isolated cDNA encoding two types of MIH, Pem-MIH1 and Pem-MIH2, from the black tiger shrimp, Penaeus monodon on the basis of sequence homology to MIH from two other shrimp species. The full-length cDNA of Pem-MIH1 was characterized. Pem-MIH1 cDNA harbored 318 bp open reading frame that coded for a translated product containing 28 amino acids of the signal peptide and a putative mature Pem-MIH of 77 amino acids. The recombinant Pem-MIH1 was expressed in Pichia pastoris as a secreted protein. After purification by gel filtration, the purified Pem-MIH1 exhibited the ability to extend molting duration of P. monodon from 11.8 days to 16.3 days suggesting that Pem-MIH1 be responsible for molt-inhibiting function in the shrimp. The attempt to clone Pem-MIH1 and Pem-MIH2 genes was achieved by direct PCR amplification and PCR-based genome walking strategy, respectively. The structure of both Pem-MIH genes, containing three exons interrupted by two introns, was similar to each other and also to that of MIH genes of other crustaceans reported so far. Expression study of Pem-MIH1 and Pem-MIH2 in various tissues of P. monodon revealed the difference in expression patterns. Pem-MIH1 expressed in both the eyestalk and the thoracic ganglia whilst Pem-MIH2 expression was limited to the eyestalk. The expression of MIH in non-eyestalk tissue may suggest additional role of this hormone.     

Chemotaxis in the Florida spiny lobster, Panulirus argus

The relative importance of input from chemoreceptors on the medial versus the lateral antennular flagellae of the spiny lobster, Panulirus argus, in olfactory orientation is examined. Ablation experiments show that input from the lateral filament, specifically the aesthetase tuft of the lateral filament, is necessary and sufficient to trigger searching behaviour in this organism when stimulated with a gradient of dilute shrimp extract. P. argus locates the odour source by using this lateral filament input in both tropotactic and klinotactic comparisons of odour intensities.     

Intestinal absorption of hexoses in rats infected with Nippostrongylus brasiliensis

The net absorption and accumulation of d-galactose and d-glucose by the small intestine of rats infected with N. brasiliensis were studied in vivo and in vitro. There was no change from control levels in the rate of galactose transfer in vivo by the entire intestine 10 days after infection but fluid transfer was significantly lower at this time. Mucosal galactose transfer in vitro by the entire intestine or by each one-third of the intestine did not change significantly during infection but 10 days after infection mucosal glucose transfer was significantly lower in the infected proximal one-third of the intestine and significantly greater in the distal one-third than in the comparable segments in controls; mucosal glucose transfer by the entire intestine was not affected by infection. Serosal transfer of both hexoses by the proximal two-thirds of the intestine and by the entire intestine was significantly reduced 10 days after infection. Between 10 and 18 days after infection the rate of serosal galactose transfer in vitro was significantly lower than control levels. The difference in response of mucosal and serosal hexose transfer rates to infection appears to be due, in part, to an increase in intestinal glucose metabolism or increased tissue retention of galactose during infection. Mucosal fluid transfer in vitro by the entire intestine was not significantly different from control levels at 10 days of infection when either hexose was used, although there was a significant reduction in the jejunal segment when glucose was used. Mucosal fluid transfer by the entire intestine in the presence of galactose was significantly greater during the rejection phase of the parasite population than in controls.     

Nippostrongylus brasiliensis and Haemonchus contortus: Function of the excretory ampulla of the third-stage larva

An improved technique for measuring the water content of nematodes is described using an electronic interferometer. Changes in phase of a laser beam passing through a known pathlength of the nematode have been used to measure the refractive index and hence the water content and relative volume of the animal. Third-stage larvae of Nippostrongylus brasiliensis and Haemonchus contortus which possess an excretory ampulla, differed from second-stage larvae lacking this ampulla in requiring a greater fall in the osmolarity of artificial tap water before there was a significant increase in their water content. Increases in the pulsation frequency of the ampulla also occurred in less hypotonic solutions than those required to increase the water content of the third-stage larvae. The ampulla pulsation frequency of third-stage larvae of N. brasiliensis increased after locomotor activity in hypotonic tap water and locomotory wave frequency of third-stage larvae of N. brasiliensis was independent of the extent of hypotonicity for a range of solutions that reduced wave propogation by its second-stage larva. The results suggest that the ampulla is an adaptation to hypotonic conditions favouring a volume homeostasis that is required for optimal locomotor activity of the third-stage infective larvae of these nematodes.     

Characterization,expression and localization of valosin-containing protein in ovaries of the giant tiger shrimp Penaeus monodon

Valosin-containing protein (VCP), a member of the ATPase-associated with diverse cellular activity (AAA) family, was identified from the giant tiger shrimp (Penaeus monodon). The full-length cDNA of the PmVCP mRNA consisted of 2724 bp containing an ORF of 2367 bp corresponding to a deduced polypeptide of 788 amino acids. The deduced PmVCP protein contained two putative Cdc48 domains (positions 17–103, E-value = 2.00e− 36 and 120–186, E-value = 3.60e− 11) and two putative AAA domains (positions 232–368, E-value = 3.67e− 24 and 505–644, E-value = 3.73e− 25). PmVCP mRNA expression in ovaries was greater than that in testes in both juveniles and broodstock. PmVCP was significantly up-regulated in stages II and IV ovaries in intact wild broodstock (P < 0.05) but it was not differentially expressed during ovarian development in eyestalk-ablated broodstock (P > 0.05). The expression level of PmVCP mRNA in ovaries of 14-month-old shrimp was not affected by progesterone injection (0.1 μg/g body weight, P > 0.05). In contrast, exogenous 5-HT administration (50 μg/g body weight) resulted in an increase of PmVCP mRNA in ovaries of 18-month-old shrimp at 6 and 24 h post-injection (hpi) (P < 0.05). The rPmCdc48-VCP protein and its polyclonal antibody were successfully produced. Cellular localization revealed that PmVCP was localized in the ooplasm of previtellogenic oocytes. Subsequently, it was translocated into the germinal vesicle of vitellogenic oocytes. Interestingly, PmVCP was found in nucleo-cytoplasmic compartments, in the cytoskeletal architecture and in the plasma membrane of mature oocytes in both intact and eyestalk-ablated broodstock.     

Nippostrongylus brasiliensis and Nematodirus battus: Changes in numbers and weight during the course of infection

Nematodirus battus has been shown to be subject to a “self-cure” mechanism when lambs 6 weeks of age are infected with 60,000 larvae. It is proposed that this self-cure phenomenon is an immune response similar to that which occurs in rats infected with Nippostrongylus brasiliensis. Changes in the weight of adult Nematodirus sp. and Nippostrongylus sp. occur over the period of an infection in their hosts. Females of both species from high-dose infections increased in weight up to that time postinfection where most adult worms were present, then decreased in weight with the onset of rejection from the host. Male Nematodirus sp. showed a similar pattern of weight change to that of females but male Nippostrongylus sp. maintained a steady weight throughout the infection. The consequences of these changes in weight are discussed with relevance to expression of enzyme activities of the nematodes on a weight of individual nematode basis.