Effect of salt content on the denaturation of pike eel (Muraenesox cinereus Forsskål, 1775) actomyosin

Investigated were the effects of the salt content on the denaturation of actomyosin (AM) extracted from the dorsal muscle of pike eel, Muraenesox cinereus. The results indicated a notable amount of secondary structure change, particularly the α‐helix. Increasing the salt concentration reduced the Ca‐ATPase activity. Surface hydrophobicity of AM increased concomitantly with an increase in the salt concentration. Total and reactive sulfhydryls also changed with an increase in the salt concentration. Results of differential scanning calorimetry (DSC) indicated that the salt‐curing led to some shifts from high to lower transitional temperatures. Disulfide linkages and hydrophobic interactions appear to be critical for the changes in actomyosin.     

Age,growth, and reproduction of blackspot snapper Lutjanus fulviflammus (Forsskål 1775) around Yaeyama Islands,southern Japan,between 2010 and 2014

Age, growth, and reproductive characteristics of blackspot snapper Lutjanus fulviflammus around the Yaeyama Islands (24°N, 124°E) in southern Japan were investigated between 2010 and 2014. Samples were caught by angling or purchased monthly at fish markets to cover all size ranges and seasons. Specimens consisted of 280 females (176–347 mm fork length), 177 males (193–325 mm), and 17 juveniles (42–128 mm). Spawning was confirmed from April to August by the presence of postovulatory follicles, which, based on the occurrence of yolked oocytes possibly also occurred in March and September. Maximum fork length and age in the specimens around Yaeyama Islands were 347 mm and 23 years for females and 325 mm and 21 years for males. These results were compared to those reported previously for the species in other regions by standardized criteria. Possible spawning duration of 7 months in the population around Yaeyama Islands is similar to that in New Caledonia (22°S, 5 months) and Okinawa Island (26°N, 6 months), but shorter than that in Tanzania (8°S) and the southern Arabian Gulf (25°N) (~12 months). The maximum body sizes and ages around Yaeyama Islands are also similar to the populations in New Caledonia and Okinawa Island (>300 mm FL, >20 years old), but larger/older than those in Tanzania and the southern Arabian Gulf (<300 mm FL, <20 years old). These differences are thought to reflect water temperature, i.e. spawning duration is shorter in lower temperature regions (annual mean <26°C, New Caledonia, Okinawa Island, Yaeyama Islands) than in higher temperature regions (annual mean >27°C, Tanzania, southern Arabian Gulf). Subsequently, a shorter spawning duration extends the life‐span as well as the maximum body size. Longevity of blackspot snapper is thought to be negatively correlated with the duration of the spawning season.     

Feeding habits of the king soldier bream,Argyrops spinifer (Forsskål, 1775) (Perciformes: Sparidae), in the northern Persian Gulf

The feeding habits of the king soldier bream Argyrops spinifer (Forsskål, 1775), were examined in the northern part of the Persian Gulf (coastal waters of Bushehr, Iran). The stomach contents of 622 specimens, 13.5–64.2 cm in total length, collected by a trawl boat from June 2010 to May 2011, were analysed to assess the influence of size, season and sex on their diet composition. Amongst the examined stomachs, 57 were empty (vacuity index = 9.2%), which varied significantly (P < 0.05) throughout the year. According to the results, this species is a generalist carnivorous feeder with a diet consisting of 52 different prey items belonging to nine main categories. Bivalvia, Gastropoda, Malacostraca, Crustacea and Teleostei were the most important prey items. Fish size and gender showed no significant effects on diet composition. Moreover, in the main food catagories no seasonal variations were detected.     

Length‐weight relationship and seasonal effects of the Summer Monsoon on condition factor of Terapon jarbua (Forsskål, 1775) from the wider Gulf of Aden including Socotra Island

The present study investigates the length‐weight relationship and condition factor of populations of the Indo‐Pacific fish Terapon jarbua ( Forsskål, 1775 ) collected in the wider Gulf of Aden, notably from Socotra Island and the Hadramout coast of Yemen. This region displays a monsoon climate, with wide seasonal variations affecting estuarine habitats. A total of 620 specimens collected in estuaries and at sea were measured and weighed during field surveys carried out in 2007 and 2008 during pre‐ and post‐ South‐Western monsoon periods. The length‐weight relationship of the studied populations of Terapon jarbua was determined as W = 0.0288 × SL^2.99, with r² = 0.96 and consistent with existing data on the species from other regions. Significant seasonal differences were found in Fulton’s condition factor of Terapon jarbua.     

Age and growth of Gerres oyena (Forsskål, 1775) on Okinawa Island, Japan

Age and growth were studied for Gerres oyena (Forsskål, 1775) on Okinawa Island, southern Japan from November 2002 to November 2005. A total of 408 samples was collected ranging from 5.85 to 19.65 cm standard length (L_SL). Male fish age was estimated at up to 6⁺ years, whereas females reached 8⁺ years as estimated by sectioned otoliths. The length–weight relationships and the von Bertalanffy growth curve were described for all individuals as: and L_t = 20.54{1 − e^{−0.1807(t+2.8462)}}, respectively. Opaque rings were formed from April to August during the spring–summer seasons.     

A histological study of maturity in male goldlined seabream Rhabdosargus sarba (Forskål, 1775) in the Oman Sea

The goldlined seabream Rhabdosargus sarba (Forskål, 1775) is farmed in several countries of the Western Pacific Rim and is a candidate species for aquaculture in the Gulf States of the Middle East. This study was undertaken to examine the onset and patterns of maturity in male goldlined seabream in support of the development of practical hatchery techniques. The testes of 337 male fish (0 + to 7 + , average FL 183 ± 20 to 315 ± 12 mm) collected from the Oman trap fishery (August 2001–April 2002; September 2002–2003) were classified into four stages, based on cell type (immature, developing, active or resting). Four spermatogenetic cell types were identified in the testes spermatogonia (types a and b), spermatocytes, spermatids and spermatozoa. Active testes appeared more regularly during the peak of the reproductive season in January and February. In March, resting testes were observed indicating the end of the reproductive season. There was clear evidence of protandry. Intersex gonads were observed in male fish from age 0 + to 7 + (33% at age 0 + to 75% at age 7 + with maximum 82% intersex frequency observed at age 5 + ). From the evidence presented, male fish age 1 + produced free‐flowing sperm under slight abdominal pressure during the period November–March.     

Rhabdosargus haffara (Forsskål, 1775) and Sphyraena flavicauda Rüppell, 1833—new Red Sea immigrants in the Mediterranean

Two Red Sea species, the sparid Rhabdosargus haffara and the sphyraenid Sphyraena flavicauda , previously unrecorded in the Mediterranean, have been recently found in the vicinity of Tel-Aviv, coast of Israel.     

Biology of the kingsoldier bream (Argyrops spinifer, Forsskål 1775; Sparidae), from the Arabian Sea, Oman

It is recognized by the FAO that management of fish resources in the western Indian Ocean is complicated by the lack of data on the basic biology and landing statistics for exploited fish species. In this paper data are presented on the population biology of kingsoldier bream, Argyrops spinifer (Forsskål 1775), in the Arabian Sea with a view to contributing towards the development of management plans for its sustainable exploitation. Samples were obtained from the Omani artisanal hand‐line fishery catch, January 2001–December 2002. Total length (L_T) of fish sampled ranged from 20 to 68 cm (males) and 25 to 70 cm (females). The male : female ratio was similar up to 55 cm L_T but the larger size‐classes were composed predominately of male fish. L_T/carcass weight (W_C) relations for male and female fish were similar and the combined data produced an equation W_C = 0.00005 × L_T^2.67. Marginal increment analysis indicated an annual cycle of opaque and translucent ring formation in otoliths that was related to the change in surface water temperature during the annual monsoon period. The opaque zone was completed in May and the translucent zone began to form in June. Female and male fish age ranged between 2 and 25 years. Both males and females exhibited similar asymptotic growth patterns; the combined von Bertalanffy growth function was L_t = 64.6(1 ? e^{[?0.142(t + 0.489)]}). Gonadosomatic indices and gonad condition of male and female fish indicated that the spawning season occurred between September and January. Size (L₅₀) and age at first maturity (A₅₀) were estimated to be 36.5 cm L_T and 5.0 years for males and 37.2 cm L_T and 5.6 years females, respectively. The results of this study provide fundamental information on the biology and population dynamics of A. spinifer in the Arabian Sea that can be used in management models for the continued sustainable exploitation of this species in the Omani demersal coastal fisheries.     

Genital Morphology and Sperm Storage in Pholcus phalangioides(Fuesslin, 1775) (Pholcidae; Araneae)

The genital morphology of female Pholcus phalangioidesis examined to clarify the composition of the uterus externus and the place of sperm storage in this species. Two conspicuous pore plates serve as exits for glandular secretion that gets discharged into the uterus externus. The secretion accumulates close to the pore plates and to some extent in the region of the heavily sclerotized valve that separates the uterus externus from the uterus internus. During copulation, the male transfers spermatozoa and male secretions into the female genital tract where they are embedded and stored in the female secretion. As Ph. phalangioidesdoes not possess any separate sperm storage organs such as receptacula seminis, the glandular secretion serves to store and fix the sperm mass in a specific position within the uterus externus itself.     

Purification and part characterization of a novel antibacterial protein Scygonadin, isolated from the seminal plasma of mud crab, Scylla serrata (Forskål, 1775)

A novel protein was isolated from the seminal plasma of the mud crab, Scylla serrata (Forskål, 1775). It exhibited an antibacterial activity against the Gram-positive bacterium Micrococcus leteus with IC90 of 0.125 mg/ml. The extraction procedure for the protein included techniques of acid extraction, ion-exchange chromatography on SP-Sepharose Fast Flow and reverse-phase liquid chromatography on Source 5R RPC. It showed a molecular mass of 10.8 kDa by SDS-PAGE. A partial 20 residue NH₂-terminal sequence was determined by Edman degradation and MS-fingerprint of the protein was conducted. Similarity search in protein databases (BLAST) revealed that the protein exhibited no significant homology to any other reported antimicrobial peptides. We propose the name Scygonadin (from the gonad of S. serrata) for this antibacterial protein.     

First record of the Lessepsian fish Siganus rivulatus (Forsskål & Niebuhr, 1775) in the Sea of Marmara (Izmit Bay,Turkey)

The marbled spinefoot, Siganus rivulatus (Forsskål&Niebuhr, 1775) was recorded for the first time in Izmit Bay, Sea of Marmara. One specimen was caught on 30 September 2019 by a small scale fisherman at depth of 25 m. The fish measured 151 mm in total length and weighted of 43.45 g. S. rivulatus is one of the Lessepsian immigrants who entered the Mediterranean more than half a century ago, and has now also easily adapted to the Sea of Marmara, which has a unique two-layered water system.     

Musculature and innervation of the neck of the desert locust,Schistocerca gregaria (Forskål)

The innervation of each of the muscles involved in mediating head movement in the desert locust Schistocerca gregaria is described in detail. The number of motor neurones to each muscle and the neutral pathway and ganglion of origin of each are deduced from both histological and electrophysiological evidence. Only two of the muscles are, on histological evidence, innervated by as few as four different neurones, while several receive more than ten, and one at least 13. Individual muscles are shown physiologically to receive, in a few cases, as many as six different motor neurones. At least six muscles are innervated by motor neurones originating in more than one ganglion. One group of four muscles consisting in total of less than 100 muscle fibres receives more than 20 different motor neurones from three different ganglia through three or four different nerve roots. In these muscles, many single muscle fibres receive innervation from at least two different ganglia. It is concluded that the segmental nature of an insect muscle can not be deduced solely from a knowledge of the ganglion of origin of the motor innervation to that muscle. The innervation patterns that exist today must reflect past evolutionary development, but changes in the peripheral distribution of motor neurones, or migration of motor neurone cell bodies from one ganglion to another, or the development of additional motor neurones, or several of these factors together, must have formed a part of that development.     

Ultrastructure of the Accessory Glands in Female Genitalia of Pholcus phalangioides(Fuesslin, 1775) (Pholcidae; Araneae)

Pholcus phalangioidesdoes not possess receptacular seminis. The uterus externus (genital cavity) itself functions as a sperm storage structure. Two accessory glands are situated in the dorsal part of the uterus externus; they discharge their secretory product into the genital cavity. The secretion is considered to serve primarily as a matrix for sperm storage, i.e. to keep the spermatozoa in a fixed position. The accessory glands consist of numerous glandular units, each being composed of four cells: two secretory cells are always joined and surrounded twice by an inner and an outer envelope cell. Both envelope cells take part in forming a cuticular ductule that leads from the secretory cells to the pore plates of the uterus externus. The inner envelope cell produces the proximal part of the canal close to the microvilli of the secretory cells, whereas the outer envelope cell produces the distal part of the canal leading to the pore plate. Close to the pore the latter exhibits prominent microvilli that might indicate additional secretory activity.     

Juvenile Ribbontail Stingray, Taeniura lymma (Forssk?l, 1775) (Chondrichthyes, Dasyatidae), demonstrate a unique suite of physiological adaptations to survive hyperthermic nursery conditions

Juvenile ribbontail stingrays, Taeniura lymma (Forssk?l, 1775) of the tropical West Pacific inhabit mangal and seagrass nurseries that often experience rapid and extreme increases in water temperature. We hypothesized that juvenile rays possess a thermal strategy similar to other hyperthermic specialists, in which fish prefer high temperatures, are always prepared for thermal extremes regardless of previous thermal history, and exhibit low metabolic thermal sensitivity. Critical thermal methodology was used to determine the thermal niche, and a thermal gradient used to estimate stingray final preferendum. Temperature quotients (Q ₁₀) were calculated from metabolic rates determined at three temperatures using flow-through respirometry. As predicted, juvenile rays showed a relatively small thermal niche dominated by intrinsic tolerance with limited capacity for acclimation. Thermal preference values were higher than those reported for other elasmobranch species. Interestingly, the temperature quotient for juvenile rays was higher than expected, suggesting that these fish may have the ability to exploit the thermal heterogeneity in their environment. Temperature likely acts as a directing factor in this species, separating warm tolerant juveniles from adults living in deeper, cooler waters.     

Silencing pyruvate kinase (NlPYK) leads to reduced fecundity in brown planthoppers,Nilaparvata lugens (Stål) (Hemiptera: Delphacidae)

Pyruvate kinase (PYK) operates in the glycolytic pathway, responsible for regulating the balance between glycolysis and gluconeogenesis. The previous work indicates PYK acts in development of Drosophila embryos and in embryonic muscle growth, from which it may be inferred that PYK acts in insect fecundity. More to the point, as a central enzyme in the glycolytic pathway, PYK acts in many energy‐spending functions in most organisms. On the background findings that triazophos (TZP) stimulates fecundity via increase activities of several genes in brown planthoppers, Nilaparvata lugens, we investigated the combined influence of TZP and silencing a N. lugens PYK (NlPYK) on reproduction‐linked biological performance parameters. Here, we report that TZP+dsNlPYK treatments led to reduced (by 26%) ovarian, but not fat body, protein content relative to controls. Ovarian (35%) and fat body (54%) soluble sugar contents were reduced. TZP+dsNlPYK treatments also led to reduced (by about 24%) fecundity, expressed as numbers of eggs laid. These data show directly that NlPYK acts in insect fecundity, probably via increases in glucose metabolism.     

Comparative egg morphology of six Meccus species and Triatoma recurva (Stål, 1868) Hemiptera: Reduviidae

We investigated the morphology and morphometry of eggs from the colonies of the Entomology Laboratory at ENCB‐IPN belonging to six species of the genus Meccus and Triatoma recurva, using both light and scanning electron microscopy. Egg ornamentation is an important parameter to consider in the differentiation of species. Samples were observed under a scanning electron microscope. Measurements of fifty eggs per species included length, width, and opercular diameter, which were used for the morphometric analysis. The results showed that the seven species display a polygonal ornamentation dominated by hexagons; the operculum shows also a polygonal ornamental characteristic in each species. Morphometry provided valuable information for discriminating between closely related species of the genus Meccus and Triatoma recurva, a species akin to this group, thereby facilitating the complete discrimination of these species.