Anterior Part Of Body Research Articles

Effect of temperature and body size on anterior and posterior regeneration in Hermodice carunculata (Polychaeta, Amphinomidae)

In recent years, population outbreaks of the annelid Hermodice carunculata (Polychaeta, Amphinomidae) are recurrently detected along the coastal zone of the Salento peninsula (Southern Italy), with impacts on marine benthic ecosystems. Annelida are renowned for their remarkable regeneration potential, enabling them to reform lost body parts. A handful of studies have reported posterior regeneration of H. carunculata, but anterior regeneration has not been fully explored. In this study, we investigated the capacity of H. carunculata collected in shallow coastal areas (Ionian Sea, 40°08’26.9” N 17°58’44.1” E) to regenerate anterior body parts under different temperature conditions (22 and 14 °C) and considering two different body sizes (∼ 4 g and 25 g). In addition, histological analysis and lipid analyses were carried out to detect changes in the reproductive cycle and lipid storage during ongoing regeneration. The results suggest that small and large-sized specimens of H. carunculata can regenerate efficiently anterior body parts in 12–20 weeks post amputation when kept at 22 °C. Small-sized worms kept at 14 °C regenerated slower but died in 24 weeks post amputation before regenerating a mouth, while large-sized worms kept at 14 °C were affected by a 100% mortality during blastema formation. In addition, lipid extraction analyses show that H. carunculata can regenerate during extended periods of starvation by de novo synthesizing lipid reserves and regeneration in H. carunculata does not negatively impact the reproductive cycle, as gametogenesis occurs also during the regenerative processes.

Tetrodotoxin and Its Analogues (TTXs) in the Food-Capture and Defense Organs of the Palaeonemertean Cephalothrix cf. simula.

Tetrodotoxin (TTX), an extremely potent low-molecular-weight neurotoxin, is widespread among marine animals including ribbon worms (Nemertea). Previously, studies on the highly toxic palaeonemertean Cephalothrix cf. simula showed that toxin-positive structures are present all over its body and are mainly associated with glandular cells and epithelial tissues. The highest TTXs concentrations were detected in a total extract from the intestine of the anterior part of the body and also in a total extract from the proboscis. However, many questions as to the TTXs distribution in the organs of the anterior part of the worm's body and the functions of the toxins in these organs are still unanswered. In the present report, we provide additional results of a detailed and comprehensive analysis of TTXs distribution in the nemertean's proboscis, buccal cavity, and cephalic gland using an integrated approach including high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS), confocal laser scanning microscopy with anti-TTX antibodies, light and electron microscopies, and observations of feeding behavior. For the proboscis, we have found a TTXs profile different from that characteristic of other organs and tissues. We have also shown for the first time that the major amount of TTXs is localized in the anterior part of the proboscis that is mainly involved in hunting. TTX-containing glandular cells, which can be involved in the prey immobilization, have been found in the buccal cavities of the nemerteans. A significant contribution of the cephalic gland to the toxicity of this animal has been shown for the first time, and the role of the gland is hypothesized to be involved not only in protection against potential enemies but also in immobilizing prey. The data obtained have made it possible to extend the understanding of the role and features of the use of TTXs in the organs of the anterior part of nemertean's body.

Morphological, histological and gene-expression analyses on stolonization in the Japanese Green Syllid, Megasyllis nipponica (Annelida, Syllidae)

Benthic annelids belonging to the family Syllidae (Annelida, Errantia, Phyllodocida) exhibit a unique reproduction mode called “schizogamy” or “stolonization”, in which the posterior body part filled with gametes detaches from the original body, as a reproductive unit (stolon) that autonomously swims and spawns. In this study, morphological and histological observations on the developmental processes during stolonization were carried out in Megasyllis nipponica. Results suggest that the stolon formation started with maturation of gonads, followed by the formation of a head ganglion in the anteriormost segment of the developing stolon. Then, the detailed stolon-specific structures such as stolon eyes and notochaetae were formed. Furthermore, expression profiles of genes involved in the anterior–posterior identity (Hox genes), head determination, germ-line, and hormone regulation were compared between anterior and posterior body parts during the stolonization process. The results reveal that, in the posterior body part, genes for gonadal development were up-regulated, followed by hormone-related genes and head-determination genes. Unexpectedly, Hox genes known to identify body parts along the anterior–posterior axis showed no significant temporal expression changes. These findings suggest that during stolonization, gonad development induces the head formation of a stolon, without up-regulation of anterior Hox genes.

Computer navigation-guided transpedicular excision of L4 vertebral body osteoblastoma

Abstract Osteoblastoma is a benign bone tumor that accounts for 10% of all spinal tumors and mostly arises from the posterior spinal elements. Isolated vertebral body osteoblastoma is relatively rare and generally requires extensive surgery. We report a rare case of L4 vertebral body osteoblastoma, which was managed successfully by computer navigation-guided transpedicular excision. A 22-year-old female presented with progressive lower back pain for the past six months. Radiological investigation revealed a sclerotic lesion involving the anterior cortex with a prominent central nidus in the anterior part of the L4 vertebral body. Based on the lesion size, a diagnosis of benign osteoblastoma (Enneking stage 2) was made, and she underwent computer navigation-assisted intralesional excision of the lesion by the bilateral transpedicular route. Histopathological examination confirmed the diagnosis of osteoblastoma. In the immediate postoperative period, the patient was completely relieved of symptoms, and the final follow-up magnetic resonance imaging showed no evidence of recurrence at the end of seven years. The intraoperative 3D navigation technology allowed a transpedicular minimal access approach to excise an osteoblastoma of the L4 vertebral body while preserving intervertebral stability and decreasing morbidity.

Micro-scale vertebral features in postmenopausal women with alcohol-associated and metabolic-associated fatty liver disease: ex vivo bone quality analyses.

Although epidemiological studies indicate increased fracture risk in women with alcohol-associated liver disease (AALD) and metabolic-associated fatty liver disease (MAFLD), data about their micro-scale bone features are still limited. We aimed to characterize bone quality changes in the anterior mid-transverse part of the first lumbar vertebral body collected from 32 adult postmenopausal females. Based on pathohistological assessment of the liver tissue, individuals were divided into AALD (n = 13), MAFLD (n = 9), and control group (n = 10). We analyzed trabecular and cortical micro-architecture (using micro-computed tomography), bone mechanical properties (using Vickers microhardness tester), osteocyte lacunar network and bone marrow adiposity morphology (using optic microscopy). Data were adjusted to elude the covariant effects of advanced age and body mass index on our results. Our data indicated a minor trend toward deteriorated bone quality in MAFLD women, presented in impaired trabecular and cortical micro-architectural integrity, which could be associated with bone marrow adiposity alterations noted in these women. Additionally, we observed a significant decline in micro-architectural, mechanical, and osteocyte lacunar features in lumbar vertebrae collected from the AALD group. Lastly, our data indicated that vertebral bone deterioration was more prominent in the AALD group than in the MAFLD group. Our data suggested that MAFLD and AALD are factors that could play a part in compromised vertebral strength of postmenopausal women. Also, our data contribute to understanding the multifactorial nature of bone fragility in these patients and highlight the necessity for developing more effective patient-specific diagnostic, preventive, and therapeutic strategies.

A New Species of Free-Living Nematodes (Desmodorida, Desmodoridae) in the Romanian Black Sea Waters

The paper reports the record of Pseudochromadora gomoi sp.n. in circalittoral habitats (at depths of 47–59 m) of the Romanian Black Sea waters. The species is characterized by a unispiral amphidial fovea, the presence of lateral alae stretching from the posterior end of the cardia to the level of the cloacal opening, but also shows unique features found in other Desmodorida genera (i.e., the presence of a precloacal ventral ala in males similar to several Desmodora or Echinodesmodora species and eight subcephalic setae on the head capsule). The presence of a constrictor cuticle ring and orange elongated ducts in the anterior body part as in Pseudodesmodora lacrima, Leduc and Wharton, 2010, were also noted. The morphometric measurements of our species differ from most of the Pseudochromadora species reported in specialty literature. We extracted and counted all desmodorid individuals from 9 meiobenthic samples collected in June 2020, and performed a detailed morphological analysis of 12 individuals (5 females and 7 males) belonging to our species, also highlighting the dissimilarities with the related desmodorid species.

Micro-scale assessment of bone quality changes in adult cadaveric men with congestive hepatopathy.

Congestive hepatopathy (CH) is a chronic liver disease (CLD) caused by impaired hepatic venous blood outflow, most frequently resulting from congestive heart failure. Although it is known that heart failure and CLDs contribute to increased risk for age-related fractures, an assessment of CH-induced skeletal alterations has not been made to date. The aim of our study was to characterize changes in bone quality in adult malecadavers with pathohistologically confirmed CH compared with controls without liver disease. The anterior mid-transverse part of the fifth lumbar vertebral body was collected from 33 adult malecadavers(age range 43-89 years), divided into the CH group (n = 15) and the control group (n = 18). We evaluated trabecular and cortical micro-architecture and bone mineral content (using micro-computed tomography), bone mechanical competence (using Vickers micro-hardness tester), vertebral cellular indices (osteocyte lacunar network and bone marrow adiposity), and osteocytic sclerostin and connexin 43 expression levels (using immunohistochemistry staining and analysis). Deterioration in trabecular micro-architecture, reduced trabecular and cortical mineral content, and decreased Vickers microhardness were noted in the CH group (p < 0.05). Reduced total number of osteocytes and declined connexin 43 expression levels (p < 0.05) implied that harmed mechanotransduction throughout the osteocyte network might be present in CH. Moreover, elevated expression levels of sclerostin by osteocytes could indicate the role of sclerostin in mediating low bone formation in individuals with CH. Taken together, these micro-scale bone alterations suggest that vertebral strength could be compromised in men with CH, implying that vertebral fracture risk assessment and subsequent therapy may need to be considered in these patients. However, further research is required to confirm the clinical relevance of our findings.

Diagnostic value of ultrasound in the discoid lateral meniscus of the knee

Based on the anatomical differences between discoid lateral meniscus(DLM) and normal lateral meniscus (NLM), this study aims to setting up the ultrasound examination parameters to distinguish DLM and NLM and explore the diagnostic value of these parameters on DLM. According to the inclusion, exclusion and matching criteria, 66 DLM patients(DLM group) and 132 NLM patients with other knee joint diseases(NLM group), hospitalized from October 2019 to June 2020, were included in this study. There were 18 males and 48 females in the DLM group, ranging in age from 3 to 60 years old, with a mean of (36.9±12.1) years old;36 males and 96 females in the NLM group, ranging in age from 3 to 60 years old, with a mean of (40.0±12.2) years old. Philips high frequency(3.0 to 12.0 MHz) linear array ultrasound probe was used to examine the lateral meniscus of all patients in two groups. Nine parameters including the thickness, width and the included angle of the anterior angle, body and posterior angle respectively in the lateral meniscus were measured. The included angke is formed by the chords of the upper and lower curved surfaces of the meniscus at the free edge. The independent t test was used to analyze the difference of the measured parameters between the DLM group and the NLM group. The receiver operating characteristic(ROC) curve was used to evaluate the cut-off value of each parameter for diagnosing DLM and the corresponding sensitivity, specificity, positive predictive value, negative predictive value, and area under the ROC curve(AUC). The above 9 ultrasound measurement parameters between the DLM group and the NLM group had significant statistical differences(P<0.001). The ROC curve analysis method evaluated the cut-off value and diagnostic capabilities of these nine ultrasound parameters for DLM. The results showed that the cut-off value of the included angle of anterior part, body and posterior part were 25.85°, 24.85° and 29.15 °, respectively;and the sensitivity, specificity, negative predictive value, positive predictive value and AUC were significantly higher than other parameters, which were 88%, 91%, 79%, 95%, 0.94;89%, 94%, 82%, 97%, 0.96; 92%, 97%, 86%, 98%, 0.97, respectively. Ultrasound diagnosis of DLM is feasible and reliable. The diagnostic ability of the included angle of the anterior part, body and posterior part in the lateral meniscus measured by ultrasound to diagnose DLM are significantly better than other ultrasound measurement parameters, and the sensitivity and specificity of those parameters are close to MRI. Therefore, ultrasound can be used as a reliable method for preliminary diagnosis of DLM.

Studying Annelida Body Regeneration Under Environmental Stress in Diopatra neapolitana.

The polychaete Diopatra neapolitana is a cosmopolitan annelid that can robustly regenerate both its anterior and posterior body part depending on the position of the amputation. Previous studies demonstrated that body regeneration represents a sensitive and unspecific response to environmental stresses, including contaminants and climate alterations.The posterior body regeneration of D. neapolitana is thus a suitable, ecological and relevant biomarker in ecotoxicological and ecological risk assessment assays. Here we describe the amputation process, the monitoring of the regeneration process of the polychaete D. neapolitana and the quantification of the impact of environmental stresses on its regenerative capacity.

Sexual dimorphism patterns of the White Sea threespine stickleback (&lt;em&gt;Gasterosteus aculeatus&lt;/em&gt;)

Sexual dimorphism (SD) in the threespine stickleback Gasterosteus aculeatus reflects the different roles of the sexes in reproduction and their adaptations to different ecological niches. We quantified SD in one population of marine stickleback from the White Sea, collected during the spawning period from three spawning grounds, each at a distance of 5 km or less from the others. We used a landmark-based approach to quantify variation in 44 morphometric linear traits. In total, 749 females and 693 males were analyzed. In males, anterior body parts are larger — the base of the caudal fin and armor structures such as the first and second dorsal spines and the pelvic spine. Females have larger posterior bodies — the abdomen, pelvic girdle and the third dorsal spine. The SD of caudal body parts exhibits complex patterns. In White Sea threespine stickleback, SD patterns are generally similar to other populations of the species, but more often show male-biased patterns. Female-biased size SD may be associated with the female biased sex ratio of White Sea stickleback.

MORPHOMETRIC STUDY OF SEROTONERGIC NERVOUS COMPONENTS IN PLANARIANS GIRARDIA TIGRINA

The serotonergic components in the nervous system of planarian Girardia tigrina was shown by immunocytochemical method. The whole-mounts are used to extract the maximum information and conduct a quantitative morphometric analysis of serotonin-immunopositive elements in different body regions. The planarian nervous system is represented by cephalic ganglion in the anterior body part and a pair of well-defined ventral nerve cords running along the body. The density of serotonin components is greatest in the head region, which reflects in thickness of cephalic ganglion arch (123–94 µm) and of nerve cords, gradually decreasing from head (111–97 µm) to middle (83–42 µm) and tail (64-28 µm) zones. Nerve nodes contain 4–10 serotonergic neurons in different body regions and connected by a few transverse commissures with a distance from 70 to 145 µm. Results supplement the available data and can be useful for comparative analysis of serotonergic components in free-living and parasitic flatworms.

Does the Atlantic horse mackerel Trachurus trachurus (Teleostei: Carangidae) differentiate morphologically within the putative Moroccan-Saharan stock?

ABSTRACT To discriminate potential stock units of the Atlantic horse mackerel Trachurus trachurus within the putative Moroccan–Saharan stock, we investigated the morphological variation of this species from three fishing areas (from the north to the south: Larache, Safi and Dakhla) in the Moroccan Atlantic coastal waters. We used a geometric morphometric approach based on 30 truss measures derived from 14 landmarks in 165 fish specimens. We compared fish from three areas using a multivariate analysis including discriminant analysis and Procrustes technique. We found indications of at least two subunits: a differentiated subgroup in the north off Larache, probably a self-recruiting population or a locally adapted morphotype, and two overlapped subunits, respectively in the mid and southern Moroccan Atlantic coast off Safi and Dakhla. Examination of the contribution of each morphometric variable to canonical functions indicated that differences among samples seemed to be associated with morphological changes in the anterior and posterior parts of body, which may indicate adaptations to local environmental conditions and habitat use. Further investigations using other methods are needed to confirm the identified stock units. The present study and the obtained results on such a vulnerable declining small pelagic species are of great importance for fish stock assessment management and practice, but also have ecological and evolutionary implications related to local adaptations in fish populations that are under intense fishing pressure as an induced evolutionary selective force, which affects several adaptive traits.

The serotonergic nervous system of prolecithophorans shows a closer similarity to fecampiids than to triclads (Platyhelminthes).

Prolecithophora is a poorly studied flatworm order belonging to the adiaphanidan clade, together with Tricladida and Fecampiida. The phylogenetic position of the three orders within this clade is not yet resolved. Additionally, no obvious synapomorphy other than an opaque epidermis could be found so far. In this study, the serotonergic nervous system of six different prolecithophoran species has been studied for the first time with a fluorescent immunocytochemical technique. We found that all six species show a similar pattern of the serotonergic nervous system. The typical prolecithophoran serotonergic nervous system consists of a cephalic ganglion in the anterior body part from which a pair of dorsal, ventral, and lateral longitudinal nerve cords originate. Furthermore, the three longitudinal nerve cords of one body side are connected to each other at the posterior body part by a conspicuous commissure. The ventral cords, which we consider the main cords, are most prominent and show double brain roots. A comparison of the nervous system within Adiaphanida shows clearly that prolecithophorans and fecampiids are much more similar in this regard than prolecithophorans and triclads.

Identification and characterization of a fibroblast growth factor gene in the planarian Dugesia japonica.

Planarians belong to the phylum Platyhelminthes and can regenerate their missing body parts after injury via activation of somatic pluripotent stem cells called neoblasts. Previous studies suggested that fibroblast growth factor (FGF) signaling plays a crucial role in the regulation of head tissue differentiation during planarian regeneration. To date, however, no FGF homologues in the Platyhelminthes have been reported. Here, we used a planarian Dugesia japonica model and identified an fgf gene termed Djfgf, which encodes a putative secreted protein with a core FGF domain characteristic of the FGF8/17/18 subfamily in bilaterians. Using Xenopus embryos, we found that DjFGF has FGF activity as assayed by Xbra induction. We next examined Djfgf expression in non-regenerating intact and regenerating planarians. In intact planarians, Djfgf was expressed in the auricles in the head and the pharynx. In the early process of regeneration, Djfgf was transiently expressed in a subset of differentiated cells around wounds. Notably, Djfgf expression was highly induced in the process of head regeneration when compared to that in the tail regeneration. Furthermore, assays of head regeneration from tail fragments revealed that combinatorial actions of the anterior extracellular signal-regulated kinase (ERK) and posterior Wnt/ß-catenin signaling restricted Djfgf expression to a certain anterior body part. This is the region where neoblasts undergo active proliferation to give rise to their differentiating progeny in response to wounding. The data suggest the possibility that DjFGF may act as an anterior counterpart of posteriorly localized Wnt molecules and trigger neoblast responses involved in planarian head regeneration.

The Induction of Asexual Reproduction on Holothuria scabra and Bohadschia marmorata: The Conservation Effort inTanimbar Archipelago, Maluku

Southeast Maluku is the leading supplier of Indonesian trepang, but lately, the production has been decreased significantly. The effort to increase the trepang population through sexual reproductive techniques still requires a long time. Therefore, another method which faster, more productive, and more accessible are needed to be applied by coastal communities, namely inducing asexual reproduction of fission using a rubber band. This research using experimental methods in the field and analyzed descriptively. Fission induction conducted by rubber binding at 1/3 of the anterior body part of trepang. This study induces asexual reproduction in two trepang species found on Matakus Island, Tanimbar Archipelago, Maluku, Holothuria scabra, and Bohadschia marmorata. The results showed that H. scabra (98%) and B. marmorata (100%) rubber binding could induce individual fission of the trepang and divide into two new individuals. The posterior part has a higher regeneration and a better survival rate than the anterior part. The survival rate of B. Marmorata is higher than that of H. scabra.

Seasonal variability of maternal effects in European hake Merluccius merluccius

Maternal attributes may influence the quantity and quality of offspring and hence, their survival. We evaluated the seasonal variability in maternal effects on developing oocytes and larvae of European hakeMerluccius merlucciusfrom the southern stock. Females were collected in 10 different years between 1999 and 2017 in the 3 spawning seasons identified in NW Spain (winter-spring, summer and autumn). Five indices of reproductive trait characteristics (batch fecundity [BF], relative fecundity [RBF], oocyte dry weight [ODW], oocyte diameter [OD] and oocyte lipid droplet diameter [ODD]) and 4 indices of maternal effects (total length [TL], gutted weight, hepatosomatic index [HSI] and Fulton’sK) were analysed. Additionally, larvae were sampled in 2017 during winter-spring and summer spawning peaks to study seasonal variability in their growth and allometry. The results revealed maternal effects on offspring attributes (for both oocytes and larvae) that differed among seasons in terms of productivity and oocyte quality; more and likely better-quality oocytes were produced in the winter-spring. BF, ODW and OD were influenced mostly by female size, ODD was related to HSI, and RBF was not influenced by any maternal attribute. The larval growth rate was similar, although summer larvae had more developed anterior body parts than winter-spring larvae. The temporal differences could be due to differences in maternal attributes and/or environmental conditions; these differences might impact larval survival and hence annual stock recruitment. A multi-year analysis of interactions between environmental conditions and maternal effects is required to understand the complex process of larval recruitment.

Cattle infestation by lice in Northern Tunisia

The reported study was carried out from October 2014 to January 2015 and involved 622 cattle belonging to a dairy farm in North Tunisia. Each animal was examined once for the presence of lice. The infestation prevalence was estimated at 14.3% (89/622). Three louse species were collected: Linognathus vituli (2.7%), Haematopinus eurysternus (11.4%) and Bovicola bovis (0.8%). The co-infestation prevalence was 0.6% and concerned only B. bovis and L. vituli, collected from four calves (three males and one female). Calves were infested by the three species, L. vituli (17.5%), B. bovis (5.2%) and H. eurysternus (1.0%), whereas adults were only infested by H. eurysternus (13.3%). All H. eurysternus parasites were found on the tail of the animals, whereas L. vituli was present on the whole body. B. bovis infested the anterior body parts, mainly the dorsal region (60%) (p &lt; 0.05). Clinical signs were observed only in calves under six months. The infested calves showed pruritus (63%) and depilation (37%).

Novel Technique as a Revision Surgery for Failed Anterior Cervical Corpectomy and Fusion in the Treatment of Cervical Myelopathy Due to Ossification of the Posterior Longitudinal Ligament

This article aimed to introduce a novel technique, the "seesaw technique," for failed anterior cervical corpectomy and fusion (ACCF) in the treatment of cervical ossification of the posterior longitudinal ligament. A patient who underwent ACCF 12 years ago and suffered gradually deteriorating neurologic function was referred to our institution. Preoperative imaging showed residual ossified mass at C5/6 level, causing compression to his spinal cord. He patient was treated by the seesaw technique. The main surgical procedures include removal of the plate and screws, removal of the osteophytes and diskectomy of C4/5, resection of the anterior part of C5 vertebral body, establishment of a transverse hinge at C7 vertebral body, installation of cervical plate and hoisting tool, and antedisplacement of C5 vertebral body and titanium mesh. Images were investigated before and after the procedure. The Japanese Orthopaedic Association score was used to evaluate his neurologic function, and surgery-related complications were also analyzed. The patient acquired significant improvement of his neurologic function 2 days after the surgery, and he could walk by himself without assistance. Postoperative images showed his spinal canal was enlarged sufficiently and the compression at C5/6 level was also released. At 13 months follow-up, his Japanese Orthopaedic Association score increased from 9 before surgery to 14, with an improvement rate of 62.5%. No surgery-related complications were observed during the whole follow-up. The seesaw technique provides satisfactory outcomes with wide enough decompression window and serves as a safe, effective surgical alternative for patients with failed ACCF.

Revealing the colourful side of birds: spatial distribution of conspicuous plumage colours on the body of Australian birds

In many species of birds, different body parts often display very different colours. This spatial distribution of coloured plumage patches may be determined, among other factors, by the balance between being cryptic to predators, and conspicuous to intended receivers. If this is the case, ventral and anterior body parts in birds – which are less visible to predators but more prominent to conspecifics – should present more conspicuous and sexually dichromatic plumage colours. Here, I test these predictions using reflectance spectrometric measurements of standardised plumage patches across males and females for nearly an entire avifauna (Australian landbirds, n = 538 species). My data show that, as predicted, conspicuous and sexually dichromatic colours are mainly located near the head, while the plumage of the back is the most cryptic. One clear exception to this pattern is the conspicuous rump coloration. In many species, this patch can be concealed by wings, and therefore exposed only when necessary. In addition, conspicuous rump coloration could deflect or confuse predators in case of attack. However, there is considerable variation across species, and this makes position on the body a very poor predictor of plumage elaboration (R2 &lt; 0.02). Future studies should try to determine whether differences between species in the distribution of colours across the plumage are due to variation in ecological factors (predation risk, habitat, etc.).

Biphasic moult cycle of the parasitic isopod Norileca indica (H. Milne Edwards, 1840) (Isopoda: Cymothoidea): stage-wise characterisation and haemolymph ecdysteroids titre

AbstractNorileca indica (H. Milne Edwards, 1840) is a protandrous hermaphroditic and obligatory parasitic isopod of scombrid fishes. The posterior and anterior biphasic moult cycles in the adult phases (male, transitional, and female) of this species are characterised based on the microscopic changes reflected in the uropod exopodite and maxillule, respectively. Biphasic parturial moult as well as the moult removing the old brood pouch characteristic of ovigerous females was recorded. Assay of haemolymph ecdysteroids titre with respect to different biphasic moult cycle stages appears to be first report of its kind among aquatic and/or parasitic isopods. The ecdysteroids titre showed significant fluctuation in relation to the moult cycle stages, while the parasite was at a biphasically intermoult stage, titre was estimated to be 13.64 ± 2.09 ng ml–1. By the onset of the premoult at the posterior body region, titre showed a gradual increase and reached a maximum level (328.54 ± 70.17 ng ml–1; P = 0.0060) when the parasite was at late premoult at the posterior body part and mid premoult stage at the anterior body part. There was a subsequent sharp decline (92.8 ± 12.95 ng ml–1; P = 0.002) soon after the ecdysis of the posterior part by the time premoult changes in the anterior part advanced as late premoult and about to moult. The level of ecdysteroids titre was 55.56 ± 14.47 ng ml–1 when the parasite completed anterior ecdysis and reached postmoult. Data on the monthly occurrence of biphasic moult cycles revealed that a mean average of 23.26% of the adult population undergoes premoult/ecdysis/postmoult activities throughout the year. The rate of moulting showed a decline (16.12 ± 0.60%) during the monsoon months (June-August) when compared to pre-summer/summer (February-May) (24.83 ± 2.42%) and post-monsoon/winter (September-January) (26.28 ± 1.75; P = 0.005).