Ovarian Lobes Research Articles

Small Molecule Activator of the Human Epithelial Sodium Channel

The epithelial sodium channel (ENaC), a heterotrimeric complex composed of alpha, beta, and gamma subunits, belongs to the ENaC/degenerin family of ion channels and forms the principal route for apical Na(+) entry in many reabsorbing epithelia. Although high affinity ENaC blockers, including amiloride and derivatives, have been described, potent and specific small molecule ENaC activators have not been reported. Here we describe compound S3969 that fully and reversibly activates human ENaC (hENaC) in an amiloride-sensitive and dose-dependent manner in heterologous cells. Mechanistically, S3969 increases hENaC open probability through interactions requiring the extracellular domain of the beta subunit. hENaC activation by S3969 did not require cleavage by the furin protease, indicating that nonproteolyzed channels can be opened. Function of alphabetaG37Sgamma hENaC, a channel defective in gating that leads to the salt-wasting disease pseudohypoaldosteronism type I, was rescued by S3969. Small molecule activation of hENaC may find application in alleviating human disease, including pseudohypoaldosteronism type I, hypotension, and neonatal respiratory distress syndrome, when improved Na(+) flux across epithelial membranes is clinically desirable.

AP-2-dependent Internalization of Potassium Channel Kir2.3 Is Driven by a Novel Di-hydrophobic Signal

The localization and density of Kir2.3 channels are influenced by the balance between PDZ protein interaction at the cell surface and routing into the endocytic pathway. Here, we explore mechanisms by which the Kir2.3 channel is directed into the endocytic pathway. We found that Kir2.3 channels are constitutively internalized from the cell surface in a dynamin-dependent manner, indicative of vesicle-mediated endocytosis. The rate of Kir2.3 endocytosis was dramatically attenuated following RNA interference-mediated knockdown of either alpha adaptin (AP-2 clathrin adaptor) or clathrin heavy chain, revealing that Kir2.3 is internalized by an AP-2 clathrin-dependent mechanism. Structure-rationalized mutagenesis studies of a number of different potential AP-2 interaction motifs indicate that internalization of Kir2.3 is largely dependent on a non-canonical di-isoleucine motif (II413) embedded within the C terminus. Internalization assays using CD4-Kir2.3 chimeras demonstrate that the di-isoleucine signal acts in an autonomous and transplantable manner. Kir2.3 co-immunoprecipitates with alpha adaptin, and disruption of the di-isoleucine motif decreased interaction of the channel with AP-2. Replacement of the di-isoleucine motif with a canonical di-leucine internalization signal actually blocked Kir2.3 endocytosis. Moreover, in yeast three-hybrid studies, the Kir2.3 di-isoleucine motif does not bind the AP-2 alphaC-sigma2 hemicomplex in the way that has been recently observed for canonical di-leucine signals. Altogether, the results indicate that Kir2.3 channels are marked for clathrin-dependent internalization from the plasma membrane by a novel AP-2-dependent signal.

An anomalous White Mullet, Mugil curema (Perciformes: Mugilidae), with three ovarian lobes found in the Gulf of Cariaco, Venezuela

Una lisa blanca, Mugil curema Valenciennes (Perciformes: Mugilidae), de 386 que fueron examinadas en el Golfo de Cariaco, Venezuela, entre 1984 y 1985, tenía un tercer lóbulo completo en el ovario. El pez medía 24.8 cm de largo y pesaba 280 gramos. Las dos mitades del lóbulo doble del ovario estaban separadas por un septo grueso y fibroso y contenían óvulos atrésicos. Los óvulos atrésicos tenían formas grotescas y estaban sufriendo liquefacción y produciendo macrófagos. La mayoría de los óvulos parecían haber sido retenidos por una obstrucción distal. No se encontró evidencia de neoplasma. Este fenómeno puede estar relacionado con el aumento en los niveles de contaminación del Golfo. Ninguna anomalía similar a la descrita anteriormente ha sido reportada en un pez.

Classification of differentiating oocytes during ovarian cycle in the giant freshwater prawn, Macrobrachium rosenbergii de man

Based on the light microscopic observations of cells' sizes, chromatin patterns, amount of lipid droplets and yolk granules, the female germ cells could be classified into four different phases, which include 1) oogonia (Oog), 2) primary oocytes (pOc), 3) secondary oocytes (sOc), and 4) mature oocyte (mOc). Oog are small oval-shaped cells with irregular-shaped nuclei sizing 4–6 μm in diameter. They rest on the connective tissue germinal cord at the tip of each ovarian pouch (lobule). Oogonia increase their number through mitotic division, and the daughter cells move into ovarian pouch where they undergo first meiotic division to become primary oocytes, which have various steps of 1st meiotic prophase accumulating at the innermost zone of the ovarian pouch. The primary oocytes are small oval-shaped cells (8.5–10 μm in diameter) with large nuclei containing chromatin in various states of condensation that finally transform into chromatids. Their nuclei are surrounded by thin rim of faint blue-stained cytoplasm. The secondary oocytes derived from 2nd meiosis and comprise five steps: Oc1 and Oc2, classified as previtellogenic oocytes, Oc3 and Oc4, classified as vitellogenic oocytes, and mature oocyte (mOc) The zones of ovarian pouch are defined based on the accumulation of various steps of developing oocytes, namely, oogenic, previtellogenic, vitellogenic and mature zones, respectively. The ovarian cycle is divided into five stages based on the number and types of oocytes present in each stage. Stage 0 and I are spawn and spent stages. Stage II and III are proliferative and premature stages, while stage IV is mature stage. During ovarian stage I, each ovarian pouch contains primarily oogonia, primary oocytes, Oc1 and a few Oc2. In stage II, the pouch contains mainly Oc2 and Oc3, while in stage III the predominant cells are Oc4. Mature oocytes appear synchronously, in stage IV. The ovulating mature oocytes pass through the thin disrupted wall of ovarian pouch into subcapsular space, that leads into the oviduct situated on the ventro-lateral side of the ovarian lobe. At spawning, the ovarian pouches break down and only connective sheaths and hemolymph sinuses remain. The germinal cords and islets of oogonia remain in the central area of stage 0 ovary. The ovarian capsule, including the muscular layer, becomes attenuated as the ovary progresses from stage 0 to IV. The hemolymph vessels become highly convoluted in the central area of the ovary, and they branch radially into smaller hemolymph sinuses around each oogenic pouch.

Comparative oogenesis in cardinal fishes (Apogonidae, Perciformes), with special focus on the adaptive structures of the egg envelopes

The present study compares gonad structure and oogenesis in 30 species of cardinal fish (Apogonidae) from the Indo-Pacific region. In all of the species studied the ovaries are bilobed, with each lobe possessing ovigerous lamellae whose numbers and dimensions increase concomitantly with growth of the fish and reproductive stage, and correlate with the total dimensions of the particular species. In species of the genus Siphamia, the ovarian lobes are associated with a fat body that is not found in species of the other genera studied. Some of the species studied (Siphamia spp.; Archamia spp.) demonstrate group-synchronized maturation of eggs, possibly with only one spawn per reproduction season. However, most of the Apogon spp., and other genera, have unsynchronized cycles, a characteristic of multiple spawners. The various stages of previtellogenic and vitellogenic development are similar in the different species, but differ in timing and dimensions of the oocytes around which the morphogenesis of the egg envelope (chorion) and follicle begins. Differentiation of the egg envelope and follicle cells parallels the vitellogenic stages of egg development. The number of eggs was found to correlate positively with the length of the body and ovary of the fish, whereas egg diameter was found to correlate negatively with body length. The surface of the egg envelope bears ridges that form patterns of various types, whose structures and dimensions seem to be species-specific, and which in most species converge upon the single micropyle on the animal pole. The exposed ridge mazes include a special fibrous web that anchors in the micropyle. The production and importance of these ridges, as well as the correlations between egg numbers per spawn, egg dimensions, and the oral dimensions of the paternal male, are discussed.

Histological studies of the ovaries of two tropical portunid crabs, Portunus pelagicus (L.) and Scylla serrata (F.)

Summary The histology of ovaries of adult crabs, Portunus pelagicus and Scylla serrata, were studied and compared using light microscopy. In general, the histological features, the steps of oogenetic cells and the stages of ovarian development appear similar in the two species. The ovary possesses three to four lobes, and each lobe is divided into lobules. A thick capsule surrounds the ovarian lobes and its extensions cover and separate each lobule. The lobule is composed of follicles, each containing a cluster of oocytes at different steps within the confinement of connective tissue trabeculae. There are five steps of oogenetic cells, i.e., oogonia (Og) and four steps of oocytes (Oc1, Oc2, Oc3, Oc4). Og are the earliest germ cells and are located in the center of each lobule. They divide mitotically and move into each follicle where they become Oc1. Oc2 rapidly increase in size, exhibits a clockface nucleus and basophilic cytoplasm. Oc2 possess larger nuclei, non-condensed chromatin, a prominent nucleolus and are intensely basophilic. Oc1 and Oc2 are previtellogenic and do not contain yolk granules. Oc3 are larger in size, with a slate grey cytoplasm and contain a few yolk granules. Oc4 are fully mature oocytes, in possession of completely dispersed chromatin in the nucleus and a very prominent nucleolus. The cytoplasm is eosinophilic due to the presence of numerous yolk granules. The Periodic acid-Schiff reaction and Sudan black stains suggest that Oc4 also contain large amounts of glycoprotein and lipid in their cytoplasm. The ovarian cycle is divided into four stages, i.e., spawn-spent (stage I), proliferative (stage II), pre-mature (stage III) and mature (stage IV). Each stage contains different cellular associations: stage I is characterized by the reconfiguration of connective tissue scaffold, plus remnants of unspawned oocytes; stage II contains numerous dividing Og and a few Oc1; stage III contains primarily Oc1, Oc2, Oc3; and stage IV contains mostly Oc4 and small clusters of Og.

Mutation of a Conserved Threonine in the Third Transmembrane Helix of α- and β-Connexins Creates a Dominant-negative Closed Gap Junction Channel

Single site mutations in connexins have provided insights about the influence specific amino acids have on gap junction synthesis, assembly, trafficking, and functionality. We have discovered a single point mutation that eliminates functionality without interfering with gap junction formation. The mutation occurs at a threonine residue located near the cytoplasmic end of the third transmembrane helix. This threonine is strictly conserved among members of the alpha- and beta-connexin subgroups but not the gamma-subgroup. In HeLa cells, connexin43 and connexin26 mutants are synthesized, traffic to the plasma membrane, and make gap junctions with the same overall appearance as wild type. We have isolated connexin26T135A gap junctions both from HeLa cells and baculovirus-infected insect Sf9 cells. By using cryoelectron microscopy and correlation averaging, difference images revealed a small but significant size change within the pore region and a slight rearrangement of the subunits between mutant and wild-type connexons expressed in Sf9 cells. Purified, detergent-solubilized mutant connexons contain both hexameric and partially disassembled structures, although wild-type connexons are almost all hexameric, suggesting that the three-dimensional mutant connexon is unstable. Mammalian cells expressing gap junction plaques composed of either connexin43T154A or connexin26T135A showed an absence of dye coupling. When expressed in Xenopus oocytes, these mutants, as well as a cysteine substitution mutant of connexin50 (connexin50T157C), failed to produce electrical coupling in homotypic and heteromeric pairings with wild type in a dominant-negative effect. This mutant may be useful as a tool for knocking down or knocking out connexin function in vitro or in vivo.

Trematodes from Red Sea Fishes: Neohypocreadium aegyptense n. sp. (Lepocreadiidae), Fairfaxia cribbi n. sp. and Macvicaria chrysophrys (Nagaty & Abdel-Aal, 1969) (Opecoelidae)

Specimens of the marine fishes Chaetodon lineolatus (Chaetodontidae), Lethrinus nebulosus (Lethrinidae) and Acanthopagrus bifasciatus (Sparidae) were caught in the Red Sea off the coast of Sharm El-Sheikh, South Sinai, Egypt. Fifteen (75%), four (16%) and fourteen (35%) fish, respectively, were found to harbour intestinal trematodes. C. lineolatus was parasitised by Neohypocreadium aegyptense n. sp. (Lepocreadiidae), L. nebulosus by Fairfaxia cribbi n. sp. (Opecoelidae) and A. bifasciatus by Macvicaria chrysophrys (Nagaty & Abdel-Aal, 1969) Bray, 1985 (Opecoelidae). N. aegyptense n. sp. is most similar to N. chaetodoni (Mahavi, 1972), but is smaller and differs in having acinous rather than digitate ovarian lobes, vitelline follicles extending anteriorly to midway between the ventral sucker and the intestinal bifurcation and an external seminal vesicle extending posteriorly to reach the anterior margin of the ovary. The generic diagnosis of Neohypocreadium is amended. F. cribbi n. sp. resembles F. lethini Cribb, 1990, but differs in having relatively smaller gonads, cirrus-sac and eggs, and larger suckers and pharynx. M. chrysophrys, collected from its type-host and locality, is redescribed. Plagioporus saoudi Ramadan, 1985 is considered its synonym.

Histological examination of final oocyte maturation and atresia in wild and domesticated Penaeus monodon (Fabricius) broodstock

Oocyte maturation and gonadosomatic index (GSI) of eyestalk ablated Penaeus monodon females collected from the wild and from two first-generation domesticated lines were assessed. Frequency and diameter of the different oocytes, and the intensity of oocyte atresia, were compared among groups through histological assessments of the sections of the middle ovarian lobe. Digitized images from ovary sections were used to record the frequency and diameter of different oocyte types. Spawning performance of the three groups were expressed in terms of the percentage of females that spawned at least once (productive females), time from eyestalk ablation to first spawning (latency period) and the number of spawnings per female stocked. Final ovarian maturation was attained in all groups, as indicated by the presence of mature oocytes with cortical rods (cortical oocytes), dark-green ovarian colour and high GSI values (5.83–6.86%). However, domesticated groups presented significant larger immature oocyte types (previtellogenic and yolky oocytes) and smaller cortical oocytes compared with wild females, indicating a reduced vitellogenic activity during final oocyte maturation. Additionally, the frequency of atresia was comparatively higher for both domesticated groups, which could be related to their inferior spawning performance. The implications of these results on the reproductive potential and development of domesticated P. monodon are discussed.

A NEW SPECIES OF OOCHORISTICA (EUCESTODA: CYCLOPHYLLIDEA) PARASITE OF CTENOSAURA PECTINATA (REPTILIA: IGUANIDAE) FROM OAXACA, MEXICO

During January 2002, 3 specimens of an undescribed species of Oochoristica Lühe, 1898, were collected in Ctenosaura pectinata (Wiegmann, 1834) from Santa Mará Mixtequilla, Oaxaca, Mexico. Oochoristica leonregagnonae n. sp. differs from 71 of 82 species of the genus by its large number of testes (78-112 [95] vs. less than 65 per proglottid, respectively). In addition, the numerous ovarian lobes (31-79 [51]) possessed by the new species distinguish it from the other 10, with a maximum of 20 ovarian lobes. The new species differs from Oochoristica acapulcoensis Brooks, Pérez-Ponce de León and García-Prieto, 1999, which also infects C. pectinata in Mexico, by the presence of numerous staining granules throughout the parenchyma of the scolex in the latter species; likewise, testes in O. acapulcoensis reach and even overpass the excretory canals, whereas in the new species they are limited to the central region between these tubules.

A new species of Rhinebothroides Mayes, Brooks & Thorson, 1981 (Cestoda: Tetraphyllidea) from the ocellate river stingray in Argentina, with amended descriptions of two other species of the genus.

A new species of the tetraphyllidean genus Rhinebothroides Mayes, Brooks & Thorson, 1981 is described from the spiral intestine of specimens of the ocellate river stingray Potamotrygon motoro (Müller & Henle) collected in the Río Colastiné, Argentina. R. campbelli n. sp. can be distinguished from its congeners particularly in worm size (up to 7 mm long), the number of segments (5-7), the number of testes per segment (26-41), the extension of the ovarian lobes and the absence of darkly-staining cells surrounding the distal end of the cirrus-sac. Comparison of tapeworms matching the original description of R. mclennanae Brooks & Amato, 1992 with the type-specimens of R. glandularis Brooks, Mayes & Thorson, 1981 showed that these are two distinct species. Consequently, R. mclenannae is considered a valid species rather than a synonym of R. glandularis, as suggested by Marques & Brooks (2003). R. mclennanae can be distinguished from R. glandularis by the morphology of the ovary, the number of medial loculi in the bothridia, the number of testes per mature segment and cirrus-sac size. It is concluded that variation in microthrix form and density may prove to be of taxonomic utility for distinguishing species of Rhinebothroides. Some comments on characters noted by Marques & Brooks (2003) in their revision of the genus are also provided, such as the absence of an external seminal vesicle in R. mclennanae and R. glandularis, the absence of microtriches in the genital atrium, intraspecific variation of bothridial shape and ovarian shape.

Frequent and unexplained gonadal abnormalities in whitefish (central alpine Coregonus sp.) from an alpine oligotrophic lake in Switzerland

The occurrence of a large number of whitefish with morphologically altered gonads in Lake Thun (Switzerland) has been reported by commercial fishermen since the year 2000. Macroscopic and microscopic examination of gonads revealed that 35% (281 out of 808) of whitefish from Lake Thun were affected. Frequency of gonadal abnormalities varied significantly with sex, age and ecotype of whitefish. Apparent females (26% [106/408]) showed significantly less gonadal alterations than apparent males (40% [151/225]). Fish with deformed gonads were observed in all age classes from 1 to 6 yr, but were most frequent in the year classes 3+ to 5+. The gonadal alterations showed different frequencies among the 3 ecotypes of whitefish living in the lake: 1 ecotype was less affected (26%) than the other 2 forms (41% and 32%, respectively). The gonadal alterations included adhesions/fusions to the peritoneal wall and the lateral trunk musculature (overall: 5%; in females: 5%; in males: 5%), asymmetry (4%; 6%; 4%), atrophy (4%; 6%; 1%), compartmentations (11%; 4%; 18%), constrictions (3%; 1%; 7%) and hermaphroditism (1.1% of sampled fish, and 10 additional specimens collected by fishermen during the filleting process). In some cases, more than one alteration was observed in the same fish. Hermaphroditism manifested as 3 different types: (1) the lobular type, in which a consecutive sequence of testicular and ovarian lobes are found on the same gonad strand; (2) discrete gonads within one fish, with one gonad strand being ovarian tissue and the other being testicular tissue; and (3) the mosaic type, in which oocytes lie in tissue with normal testicular morphology, or spermatids or sperm are present in ovarian tissue. Several features of the gonadal alterations described in this study of whitefish from Lake Thun have also been reported for whitefish from other areas. However, the Lake Thun situation appears to be unique because of the high prevalence of fish affected and the broad variation of abnormal features. The causes of the frequent appearance of these gonadal alterations in whitefish from Lake Thun remain unclear.

Evidence for intersubunit interactions between S4 and S5 transmembrane segments of the Shaker potassium channel.

Voltage-gated potassium channels are transmembrane proteins made up of four subunits, each comprising six transmembrane (S1-S6) segments. S1-S4 form the voltage-sensing domain and S5-S6 the pore domain with its central pore. The sensor domain detects membrane depolarization and transmits the signal to the activation gates situated in the pore domain, thereby leading to channel opening. An understanding of the mechanism by which the sensor communicates the signal to the pore requires knowledge of the structure of the interface between the voltage-sensing and pore domains. Toward this end, we have introduced single cysteine mutations into the extracellular end of S4 (positions 356 and 357) in conjunction with a cysteine in S5 (position 418) of the Shaker channel and expressed the mutants in Xenopus oocytes. We then examined the propensity of each pair of engineered cysteines to form a metal bridge or a disulfide bridge, respectively, by examining the effect of Cd2+ ions and copper phenanthroline on the K+ conductance of a whole oocyte. Both reagents reduced currents through the S357C,E418C double mutant channel, presumably by restricting the movements necessary for coupling the voltage-sensing function to pore opening. This inhibitory effect was seen in the closed state of the channel and with heteromers composed of S357C and E418C single mutant subunits; no effect was seen with homomers of any of the single mutant channels. These data indicate that the extracellular end of S4 lies in close proximity to the extracellular end of the S5 of the neighboring subunit in closed channels.

Flavonoid Inhibition of Sodium-dependent Vitamin C Transporter 1 (SVCT1) and Glucose Transporter Isoform 2 (GLUT2), Intestinal Transporters for Vitamin C and Glucose

Vitamin C and flavonoids, polyphenols with uncertain function, are abundant in fruits and vegetables. We postulated that flavonoids have a novel regulatory action of delaying or inhibiting absorption of vitamin C and glucose, which are structurally similar. From six structural classes of flavonoids, at least 12 compounds were chosen for studies. We investigated the effects of selected flavonoids on the intestinal vitamin C transporter SVCT1(h) by transfecting and overexpressing SVCT1(h) in Chinese hamster ovary cells. Flavonoids reversibly inhibited vitamin C transport in transfected cells with IC(50) values of 10-50 microm, concentrations expected to have physiologic consequences. The most potent inhibitor class was flavonols, of which quercetin is most abundant in foods. Because Chinese hamster ovary cells have endogenous vitamin C transport, we expressed SVCT1(h) in Xenopus laevis oocytes to study the mechanism of transport inhibition. Quercetin was a reversible and non-competitive inhibitor of ascorbate transport; K(i) 17.8 microm. Quercetin was a potent non-competitive inhibitor of GLUT2 expressed in Xenopus oocytes; K(i) 22.8 microm. When diabetic rats were administered glucose with quercetin, hyperglycemia was significantly decreased compared with administration of glucose alone. Quercetin also significantly decreased ascorbate absorption in normal rats given ascorbate plus quercetin compared with rats given ascorbate alone. Quercetin was a specific transport inhibitor, because it did not inhibit intestinal sugar transporters GLUT5 and SGLT1 that were injected and expressed in Xenopus oocytes. Quercetin inhibited but was not transported by SVCT1(h). Considered together, these data show that flavonoids modulate vitamin C and glucose transport by their respective intestinal transporters and suggest a new function for flavonoids.

Anindobothrium n. gen. (Eucestoda: Tetraphyllidea) inhabiting marine and freshwater potamotrygonid stingrays.

Anindobothrium n. gen. is proposed to accommodate Caulobothrium anacolum inhabiting Himantura schmardae from Colombia, and 2 new species, one inhabiting Potamotrygon orbigny in Brazil and the other inhabiting Paratrygon aereiba in Venezuela. Members of the new genus resemble members of Pararhinebothroides, Rhinebothroides, and Anthocephalum by having bothridia with poorly differentiated apical suckers and vasa deferentia expanded into external seminal vesicles. It further resembles Pararhinebothroides, Rhinebothroides, and Anthocephalum cairae by having vas deferens inserted near the poral rather than aporal end of the cirrus sac. The 3 species assigned to the new genus form an apparent monophyletic group, based on the possession of 3 putative synapomorphies: (1) genital pores in the anterior 1/4 of the proglottid, a trait that is unusual, but not unique, among phyllobothriids; (2) anteroventral ovarian lobes converging to the center of the proglottid, a character not previously reported for phyllobothriids; and (3) ovarian lobes comprising a loose network of digitiform processes.

Four new species of Acanthobothrium (Cestoda: Tetraphyllidea) from the whiptail stingray Dasyatis brevis in the Gulf of California, Mexico.

Examination of the spiral intestines of 29 whiptail stingrays, Dasyatis brevis, from 6 sites in the Gulf of California, Mexico in 1993 and 1996 resulted in the discovery of 4 new species of Acanthobothrium: Acanthobothrium bullardi, Acanthobothrium dasi, Acanthobothrium rajivi, and Acanthobothrium soberoni. This brings the total number of species of Acanthobothrium known from the eastern Pacific Ocean to 34. With 22 additional species reported from elasmobranchs from the western Atlantic Ocean, and over 100 species globally, the number of interspecific comparisons required to justify the designation of a new species is rather unwieldy. To facilitate these and future comparisons, and in the absence of a phylogenetic hypothesis for this genus, the 56 species of Acanthobothrium from these 2 geographic regions were categorized for 4 characters: total length (< or = or > 15 mm), number of segments (< or = or > 50 segments), number of testes (< or = or > 80), and symmetry of poral and aporal ovarian lobes. These 56 taxa and their categories are presented in tabular form. Based on these characters, A. bullardi, A. dasi, and A. rajivi are category 2 species (they are relatively small, possess few segments, relatively few testes, and exhibit asymmetrical ovaries); A. soberoni is a category 6 species (it is a relatively longer worm with a larger number of segments, but with fewer testes and an asymmetrical ovary). All 4 species differ from 1 another and from species in other geographic regions in further subtleties of these 4 characters as well as hook size and relative length of hook prongs, cirrus sac size, genital pore position, number of columns of testes anterior to the cirrus sac, and number of postvaginal testes. Five specimens that appear to represent a new species of Acanthobothroides were also collected. This species is figured and some details of the morphology are described, but the material was considered to be insufficient to allow for formal description of this species at this time. This is the first record of either of these genera of onchobothriid tapeworms from the Gulf of California.

Sexual Maturation, Annual Reproductive Cycle, and Spawning Periodicity of the Shore Scorpionfish, Scorpaenodes littoralis

The ovarian structure, sexual maturation, annual reproductive cycle, and spawning periodicity of the shore scorpionfish, Scorpaenodes littoralis, in Uchiura Bay, central Japan, were examined using specimens collected between May 1995 and March 1998 and fishes reared in laboratory. The ovarian stroma and blood vessels run longitudinally through the center of each ovarian lobe. The ovarian peduncles radiate from the central stroma. During the spawning season, gelatinous material is secreted from the epithelia of both the ovarian peduncle and ovarian wall, and the epithelia show morphological changes accompanying the ovarian maturation cycle. The minimum standard length at maturity was 55.2 mm for males and 40.2 mm for females. Males with mature testes were collected from March to November. Females in the mature or post spawning stages were collected between May and October, when the mean gonadosomatic indices were also high. This indicates that the spawning season of this species occurs between May and October. Four successive types of oocytes were grouped in the mature ovary, comprised of mature, late and early vitellogenic and previtellogenic oocytes respectively, suggesting that this species is a multiple spawner. Four captive females spawned repeatedly at intervals of 2–8 days over a prolonged period (4–8 months); a 2-day spawning interval was the most common for all females. This suggests that female S. littoralis have a 48-h spawning cycle in captivity.

Two New Species of Oochoristica Luhe, 1898 (Eucestoda: Cyclophyllidea: Anoplocephalidae: Linstowiinae) Parasitic in Ctenosaura spp. (Iguanidae) from Costa Rica and Mexico

Five species of Oochoristica, Oochoristica osheroffi, Oochoristica gracewileyae, Oochoristica whitentoni, and 2 new species described herein have strobilae longer than 200 mm, many secondary ovarian lobes, and testes extending anteriorly to midovarian level. A combination of 3 characters distinguishes the 5 species from each other. Oochoristica osheroffi has an average of 68 testes per proglottid, ovarian lobes wider than long, and osmoregulatory canals not forming an anastomosing plexus; O. gracewileyae has an average of 113 testes per proglottid, ovarian lobes longer than wide, and osmoregulatory canals not forming an anastomosing plexus; O. whitentoni has an average of 125 testes per proglottid, ovarian lobes wider than long, and osmoregulatory canals forming an anastomosing plexus; a new species in Ctenosaura similis from Costa Rica has an average of 62 testes per proglottid, ovarian lobes longer than wide, and osmoregulatory canals forming an anastomosing plexus; and a new species in Ctenosaura pectinata from Mexico has an average of 122 testes per progottid, ovarian lobes longer than wide, and osmoregulatory canals forming an anastomosing plexus. Oochoristica gracewileyae differs from the other 4 species by having genital pores 10-15% rather than 25-35% of proglottid length from the anterior end and by having convoluted rather than straight or sinuous transverse osmoregulatory canals. The new species from Mexico differs from the other 4 species and apparently from all described species of Oochoristica thus far by possessing darkly staining granules throughout the parenchyma of the scolex.

Endocrine balance between male and female components of the reproductive system in intersexCherax quadricarinatus (Decapoda: Parastacidae)

Intersex individuals of the crayfish Cherax quadricarinatus are functional males that also possess arrested ovaries. To study the role of eyestalk vs. androgenic gland factors in regulating the functional balance between the different components of the intersex reproductive system, andrectomy and/or unilateral destalking were performed. Andrectomized intersex speci- mens had atrophied testes and sperm ducts and showed a reduction in the number of testicular spermatogenic lobules. Large oocytes developed in their ovarian lobes, and the Gonadosomatic Index reached 1.60 ± 0.36 compared with 0.21 ± 0.03 for the control. In the polypeptide profiles of the ovarian lobes from andrectomized individuals, the 177-, 150-, and 106-kDa polypeptides pre- dominated, resembling the profile of the secondary vitellogenic ovary. The andrectomized indi- viduals neither lost their male external characteristics, such as the red patch on the propodus, nor developed ovigerous setae on their male-like pleopods. Unilateral eyestalk ablation did not cause significant differences in the male or the female components of the reproductive system compared with the control group. The maturation of the permanently arrested ovary and the arrest of the testis in andrectomized intersex individuals illustrated the central role of the androgenic gland in maintaining the endocrine balance in intersex C. quadricarinatus. J. Exp. Zool. 283:286n294, 1999. © 1999 Wiley-Liss, Inc.

A new species of Acanthobothrium van Beneden, 1849 (Cestoda: Tetraphyllidea) from Rioraja castelnaui (Chondrichthyes: Rajoidei) in coastal waters of Argentina

Acanthobothrium marplatensis n. sp. is described from the spiral intestine of the skate Rioraja castelnaui taken off Mar del Plata, Argentina. The new species is compared with those species that it most closely resembles morphologically, to species reported from other skate hosts and to species described from the same geographical region. A. marplatensis is most similar to A. paulum, A. benedeni, A. costarricense, A. fogeli, A. himanturi, A. lintoni, A. monksi, A. olseni, A. puntarenasense and A. mathiasi. All of these species share a similar combination of characters (12–40 proglottids, 20–50 testes and total length of 2–10mm). A. marplatensis can be differentiated from these species and those described from skates by a combination of the following characters: 4.79–8.44 (6.18) mm long, with 18–30 (24) proglottids, spinose cephalic peduncle 160–338 (227) long, bothridial hooks with total length 93-134 (115), 24–39 (32) testes per proglottid, cirrus-sac curved anteriorly, ovarian lobes never reaching the level of the cirrus-sac and vaginal sphincter absent. Geographically, the new species can be distinguished from A. zapterycum and three different species designated as “Acanthobothrium sp.” reported from the coast of Uruguay and Argentina by the size of the worms, number of proglottids, position of the genital pores and size of the bothridial hooks. A. marplatensis showed the greatest preference for chambers 2 and 3 of the eight chambers of the spiral intestine. The mean intensity of infection in individual hosts increased with host size and was greater in spring and summer than in cold seasons. The intensity of infection was unrelated to host sex.