Genital Papillae Research Articles

Lenisaphelenchus ulomae n. gen., n. sp. (Rhabditida: Aphelenchoididae) isolated from the body cavity of Uloma marseuli Nakane (Coleoptera: Tenebrionidae) from Japan

Summary A new aphelenchoidid entomoparasitic nematode was isolated from the body cavity of overwintering individuals of a tenebrionid beetle, Uloma marseuli, collected at Shiga, Japan. The nematode is characterised by its six equal-sized lips forming a dome shape continuous with body contour. It has a moderately thick stylet, with wide lumen, a long two-part long (conus + conophore) and elongate oval or pear-shaped metacorpus with glandular anterior part. The male spicules are separate with a well-developed condylus, triangular rostrum and smoothly and strongly curved calomus-lamina complex. A gubernaculum or apophysis is absent. There are two pairs of papilliform male genital papillae. Females lack a post-vulval uterine sac, have a seemingly vestigial rectum and anus, and conical tail. The combination of the typological characters of the species does not fit any currently accepted aphelenchoidid genus and is somewhat intermediate between the Ektaphelenchinae and Entaphelenchinae. The molecular phylogenetic analysis also suggested that the nematode is close to both Ektaphelenchoides (Ektaphelenchinae) and Peraphelenchus (Entaphelenchinae). Thus, the nematode is described and illustrated as Lenisaphelenchus ulomae n. gen., n. sp. and tentatively placed in the Ektaphelenchinae.

Agrochemicals in freshwater systems and their potential as endocrine disrupting chemicals: A South African context.

South Africa is the largest agrochemical user in sub-Saharan Africa, with over 3000 registered pesticide products. Although they reduce crop losses, these chemicals reach non-target aquatic environments via leaching, spray drift or run-off. In this review, attention is paid to legacy and current-use pesticides reported in literature for the freshwater environment of South Africa and to the extent these are linked to endocrine disruption. Although banned, residues of many legacy organochlorine pesticides (endosulfan and dichlorodiphenyltrichloroethane (DDT)) are still detected in South African watercourses and wildlife. Several current-use pesticides (triazine herbicides, glyphosate-based herbicides, 2,4-dichlorophenoxyacetic acid (2,4-D) and chlorpyrifos) have also been reported. Agrochemicals can interfere with normal hormone function of non-target organism leading to various endocrine disrupting (ED) effects: intersex, reduced spermatogenesis, asymmetric urogenital papillae, testicular lesions and infertile eggs. Although studies investigating the occurrence of agrochemicals and/or ED effects in freshwater aquatic environments in South Africa have increased, few studies determined both the levels of agricultural pesticides present and associated ED effects. The majority of studies conducted are either laboratory-based employing in vitro or in vivo bioassays to determine ED effects of agrochemicals or studies that investigate environmental concentrations of pesticides. However, a combined approach of bioassays and chemical screening will provide a more comprehensive overview of agrochemical pollution of water systems in South Africa and the risks associated with long-term chronic exposure.

Production of donor-derived eggs after ovarian germ cell transplantation into the gonads of adult, germ cell-less, triploid hybrid fish†.

In animals, spermatogonial transplantation in sterile adult males is widely developed; however, despite its utility, ovarian germ cell transplantation is not well developed. We previously showed that the interspecific hybrid offspring of sciaenid was a suitable model for germ cell transplantation studies as they have germ cell-less gonads. However, all these gonads have testis-like characteristics. Here, we tested whether triploidization in hybrid embryos could result in germ cell-less ovary development. Gonadal structure dimorphism and sex-specific gene expression patterns were examined in 6-month-old triploid hybrids (3nHybs). Thirty-one percent of 3nHybs had germ cell-less gonads with an ovarian cavity. cyp19a1a and foxl2, ovarian differentiation-related genes, were expressed in these gonads, whereas dmrt1 and vasa were not expressed, suggesting ovary-like germ cell-less gonad development. Some (26%) 3nHybs had testis-like germ cell-less gonads. Ovarian germ cells collected from homozygous green fluorescent protein (GFP) transgenic blue drum (BD) (Nibea mitsukurii) were transplanted into 6-month-old 3nHybs gonads via the urogenital papilla or oviduct. After 9months, the recipients were crossed with wild type BD. Among the six 3nHyb recipients that survived, one female and one male produced fertile eggs and motile sperm carrying gfp-specific DNA sequences. Progeny tests revealed that all F1 offspring possessed gfp-specific DNA sequences, suggesting that these recipients produced only donor-derived eggs or sperm. Histological observation confirmed donor-derived gametogenesis in the 3nHyb recipients' gonads. Overall, triploidization reduces male-biased sex differentiation in germ cell-less gonads. We report, for the first time, donor-derived egg production in an animal via direct ovarian germ cell transplantation into a germ cell-less ovary.

Gonad Development and Blood Profile of Anti-KHV DNA Vaccinated Common Carp

Koi herpesvirus (KHV) is one of pathogen that infect common carp. Alternative to prevent KHV infection is vaccination. This study aimed to observe gonad development and blood profile on the common carp was vaccinated DNA anti-KHV GP25. Vaccination was conducted on common carp broodstock at 60 days before spawning. Blood collection for profile analysis was 15 days before pre-vaccination and 30, 45, 60 days post-vaccination. Egg diameter was observed during vaccination and, when spawning was performed. Gonad somatic index was measured in spawning time. Fish were injected phosphate buffer saline as control. Three fish were used for each treatments. The results showed that development of gonads were abdomen still hard, not rounded and the genital papilla was still closed. While spawning time that were abdomen appears rounded, enlarge and soft, papilla genital expands, anal was protrudes and widened. The gonad somatic index in broodstock vaccinated was 13.75±1.57% and broodstock control was 12.15±0.65%. Egg diameters were 0.57±0.06 – 0.97±013 mm at vaccination and 1.47±0.23 – 1.53±0.12 mm at spawning. Erythrocyte was decreased significantly on 30 days post-vaccination ie 1.05±0.34 (x106 cells / mm3). Hemoglobin was decreased on the 45 days ie 5.84±0.72 g/dL and hematocrite was decreased on 30 days ie 41.48±10.90% post-vaccination. This study showed that anti-KHV GP25 DNA vaccine could reduce erythrocytes, hemoglobin and hematocrite but not affected in gonad development of common carp.

Phasmarhabditis kenyaensis n. sp. (Nematoda: Rhabditidae) from the slug, Polytoxon robustum, in Kenya

Summary A new species of Phasmarhabditis was isolated from the slug, Polytoxon robustum, from Nairobi, Kenya. The nematode was identified using morphological, morphometric, molecular and phylogenetic analyses. Phasmarhabditis kenyaensis n. sp. is characterised by an infective juvenile with the longest body length in the genus, measuring 1232 (1107-1336) μm, by the presence of males with a bursa bearing nine bilateral pairs of genital bursal papillae and one pair of papilliform phasmids flanking the tail, cephalate paired spicules, with an arc length of 71 (57-81) μm, as well as by females with a vulva located at the mid-body region and a conoid tail shape, with two phasmids located at ca 40% of the tail length. The molecular phylogeny of the new species, as inferred from its SSU (small subunit) rRNA gene, places P. kenyaensis n. sp. genetically close to undescribed phasmarhabditids from South Africa, suggesting an African grouping, while the D2-D3 (large ribosomal subunit) and ITS region analyses relate P. kenyaensis n. sp. to P. meridionalis, with weak bootstrap support. This is the third new Phasmarhabditis species described from the African continent, the new species bringing the total known complement of the genus to 14 species. A morphometric compendium to all species cultured in vivo is supplied.

Resumption of donor-origin spermatogenesis in senescent goldfish Carassius auratus (Linnaeus, 1758) following spermatogonial cell therapy

Stem cell research has come into prominence because of its applications in assisted reproductive technology and the treatment of deadly diseases. In teleost fishes, spermatogonial stem cells have been effectively used to produce surrogate gametes and progeny through germ cell transplantation technique. The present study is the first report of an innovative application of stem cell therapy in fish species for revitalising the reproductive competence of senescent individuals. Senescent male goldfish, Carassius auratus, approximately 10 years of age were procured from a fish-breeding farm and were reared locally in the lab for an additional two years. The senescence of the individuals was then evaluated and confirmed using histological analysis, gonadal index assessment, and germ-cell specific vasa gene expression. Analyses revealed absence of spermatogonial cells and other germ cells in the testes of the senescent fish (n = 5). Spermatogonial cells from sexually immature C. auratus male donor were isolated using discontinuous percoll gradients, labelled with the fluorescent dye PKH-26, and transplanted into the gonads of senescent C. auratus males through urogenital papilla. Six months after the transplant, spermatozoa were collected through applying gentle manual pressure on the abdomen and were observed under a microscope. All C. auratus males with the transplant had produced spermatozoa from the transplanted cells. This was confirmed by the retention of PKH-26 in the spermatozoa and diagnostic SSR locus. Gravid C. auratus females were artificially inseminated with the spermatozoa of those senescent males and natural spawning was allowed. As a result viable progeny were produced. These observation suggests that the reproductive competence of senescent male fishes can be revitalised through spermatogonial stem cell therapy to produce functional gametes.

Steinernema riojaense n. sp., a new entomopathogenic nematode (Nematoda: Steinernematidae) from Spain

Summary A new species of entomopathogenic nematode, Steinernema riojaense n. sp., was isolated during a survey in La Rioja province of Spain. Morphological and morphometric traits place the new species in the glaseri-group, which is characterised by having the largest infective juvenile (IJ) with an average body length in excess of 1000 μm. The IJ of S. riojaense n. sp. possess a body length of 1043 (869-1172) μm, the lateral fields are formed by eight equally spaced and developed ridges (nine incisures) in the mid-body region, giving the formula 2, 6, 8, 4, the excretory pore is located posterior to the mid-pharynx region (D% = 58), and the hyaline region occupies ca half of the tail length. The male spicules are moderately curved with a sharp tip and are golden-brown in colour with the manubrium elongate and having a length to width ratio of 1.7:1. The first-generation male tail is non-mucronate, whereas a small papilla-like mucron is developed in the second generation. There are 11 pairs of genital papillae plus a single precloacal papilla. The first-generation female possesses a moderately protruding vulva and a slightly protruding postanal swelling. The second-generation female possesses a slightly protruding vulva and a postanal swelling. The new species is further characterised by sequences of the internal transcribed spacer (ITS) and partial 28S regions (D2-D3) of the ribosomal DNA (rDNA). Phylogenetic analyses confirm that S. riojaense n. sp. belongs to the glaseri-group and forms a monophyletic subclade with other European species.

Ficophagus (Nematoda: Aphelenchoididae) from sycones of Ficus subgenus Urostigma, sections Malvanthera and Urostigma, in eastern Australia

Summary Ficophagus from collecting trips in eastern Australia, made over 15 years, are summarised and show that species of the genus occurred widely in sycones of Ficus, subgenus Urostigma, section Malvanthera. Two new species (based on morphological differences and molecular sequencing) are described: Ficophagus elizabethae sp. n. from Ficus macrophylla, F. rubiginosa and F. obliqua, and Ficophagus richardi sp. n. from Ficus obliqua; and a morphospecies, Ficophagus Morphospecies malandicus from Ficus obliqua. Ficophagus elizabethae sp. n. is characterised by having the excretory pore (EP) opening from the level of the junction of the conus and shaft of the stylet to that of the knobs, a relatively long procorpus (1.0-2.5 times length of stylet), female tail with an obliquely truncate tail with a hyaline area and a finely to broadly rounded tip which may be mucronate; post-vulval uterine sac (PUS) ca one vulval body diam. (VBD) in length; rose-thorn-shaped spicule with distinct rostrum and prominent condylus; and genital papillae arranged as largest pair adcloacal, second pair posterior to mid-tail length, and third small pair near tail tip; and was collected from Sydney in New South Wales, to Bundaberg in Queensland (QLD). Ficophagus richardi sp. n. is characterised by having the EP opening at the level of the junction of the stylet shaft and conus, a labial cap which is raised around the opening for the stylet; procorpus 0.8-1.7 times length of the stylet, PUS <1 VBD in length, long uterus, and female tail with a V-shaped hyaline area at the bluntly rounded tip; rose-thorn-shaped spicule with a small rostrum and prominent condylus, three pairs genital papillae, first and largest on anterior cloacal lip, second at 70% of tail length measured from cloacal aperture, and third near tip, and was collected from Ban Ban Springs in the south to the Bundaberg region in the mid-north of QLD. In addition, in the absence of pertinent molecular sequences, a morphospecies is described. Ficophagus Morphospecies malandicus is characterised by having the EP opening anterior to the junction of the stylet conus and shaft, procorpus 0.9-2 times length of stylet, a short PUS usually <1 VBD long, short uterus, rose-thorn-shaped spicule with a raised condylus and prominent rostrum, and three pairs of subventral papillae on the tail (one adcloacal, one posterior to mid-tail and one near tail tip); and was collected from the Atherton Tableland, QLD. A table comparing morphological characteristics is provided to help with identification of Ficophagus nematodes from figs of the section Malvanthera in eastern Australia.

Description of a new species of Aspidonema (Sachs, 1949) Andrássy, 1958(Nematoda: Bunonematidae) associated with mint leaf beetle Chrysolina herbacea (Duftschmid, 1825) from India.

This paper provides a detailed description of a new species of genus Aspidonema isolated from mint leaf beetles (Chrysolina herbacea), and is the first report of a bunonematid nematode from beetles in India. Aspidonema kashmirensis sp. nov. is characterised by females having small, asymmetrical body (L = 224-337µm, a = 13.1-20.3, b = 3.2-4.2, c = 7.2-10.7, c' = 4.0-5.7, V = 53.3-60.0), with the right side body cuticle ornamented with shields, warts and networks while the left side is provided with five longitudinal ridges. The shields are transversely-ovoid, having strongly sclerotized borders and a pair of elliptical slits for the underlying warts. Fine pores observed under SEM are present on the surface of the shields. Males have a bifid tail; long, thin, free spicules, distally hooked gubernaculum; asymmetrical, leptoderan bursa and eight pairs of genital papillae.

Sexual dimorphism of invasive knifefish (Chitala ornata) in Laguna de bay, Philippines

Chitala ornata (J.E. Gray) (Osteoglossiformes: Notopteridae) has since established abundant and nuisance populations in Laguna de Bay. A fundamental prerequisite for the development of management strategies for invasive species like C. ornata is a full understanding of its life history characteristics including sexual dimorphism. In the present study, we examined the sexual dimorphism of C. ornata. Sexes of C. ornata can be distinguished through the examination of its genital papilla wherein females show distinct morphological adaptions for effective oviposition on a spawning substrate. Comparison of means and multivariate analysis of several morphometric characters showed that sexual size dimorphism in C. ornata is female-biased which is mainly attributed to the disparity of resource expenditure between sexes for reproduction and size-dependent advantages of females in the production of more progenies with better chances of survival.

Proximate composition of commercially important fish species in southern Gulf of Lake Tana, Ethiopia

The aim of the study was to determine the proximate composition of each sex of Oreochromis niloticus, Clarias gariepinus and Labeobarbus intermedius fish species from the southern Gulf of Lake Tana, Ethiopia. The fish samples were collected during the dry season of 2014 from the three fish landing sites, i.e., Bata, Micheal and Giorgis, where local fishermen sell their catches. Species were identified via morphological examination and color. Sexes were identified by observing genital papilla and gonads after dissection. After measuring weight and length of young fish species, fish weighing 201-310 g were selected for the study. A total of 72 fish, eight and four fish per species and sexes were selected, respectively, for each site. The sample size was determined using “resource equation" method. Only edible fillet was labeled and transferred to plastic bags according to species and sex. Then the sample was transported for proximate analysis to Addis Ababa Food Science and Nutrition laboratory using icebox at about 4 °C. Fish sample composites were prepared by taking the fish samples from the three fish landing sites for each sex and species. Samples were thawed at room temperature and oven-dried at 60 °C for 72 h, then ground into a fine powder. Proximate composition was determined following the procedure of Association of Official Analytical Chemists (AOAC). Data analysis was conducted using analysis of variance (ANOVA). Nutrient content significantly varied among fish species; more protein was recorded from O. niloticus and fat from L. intermedius. Also, fat, ash and gross energy content were different between sexes; female fish contained significantly more fat and gross energy than males. In conclusion, consumers are advised to consume these species to obtain required nutrients.

Zebrafish cyp11c1 Knockout Reveals the Roles of 11-ketotestosterone and Cortisol in Sexual Development and Reproduction.

Androgen is essential for male development and cortisol is involved in reproduction in fishes. However, the in vivo roles of cortisol and specific androgens such as 11-ketotestosterone (11-KT) in reproductive development need to be described with genetic models. Zebrafish cyp11c1 encodes 11β-hydroxylase, which is essential for the biosynthesis of 11-KT and cortisol. In this study, we generated a zebrafish mutant of cyp11c1 (cyp11c1-/-) and utilized it to clarify the roles of 11-KT and cortisol in sexual development and reproduction. The cyp11c1-/- fish had smaller genital papilla and exhibited defective natural mating but possessed mature gametes and were found at a sex ratio comparable to the wildtype control. The cyp11c1-/- males showed delayed and prolonged juvenile ovary-to-testis transition and displayed defective spermatogenesis at adult stage, which could be rescued by treatment with 11-ketoandrostenedione (11-KA) at certain stages. Specifically, during testis development of cyp11c1-/- males, the expression of insl3, cyp17a1, and amh was significantly decreased, suggesting that 11-KT is essential for the development and function of Leydig cells and Sertoli cells. Further, spermatogenesis-related dmrt1 was subsequently downregulated, leading to insufficient spermatogenesis. The cyp11c1-/- females showed a reduction in egg spawning and a failure of in vitro germinal vesicle breakdown, which could be partially rescued by cortisol treatment. Taken together, our study reveals that zebrafish Cyp11c1 is not required for definite sex differentiation but is essential for juvenile ovary-to-testis transition, Leydig cell development, and spermatogenesis in males through 11-KT, and it is also involved in oocyte maturation and ovulation in females through cortisol.

Acrostichus ziaelasi n. sp. (Nematoda: Diplogastridae) isolated from the beetle Ziaelas formosanus, a tenebrionid symbiont of the termite Odontotermes formosanus with remarks on the genus Acrostichus Rahm, 1928

A diplogastrid nematode species was isolated from a termite-associated tenebrionid beetle, Ziaelas formosanus, collected from several localities in Taiwan. The new species shares a characteristic feeding structure, i.e., an extremely long and thin stoma with two genera, Rhabditolaimus and Mehdinema. However, the new species has highly characteristic male and female reproductive system, i.e., arrangement of male genital papillae, spicule and gubernaculum morphologies, and presence of female receptaculum seminis, that are similar to those of Acrostichus. A molecular phylogenetic analysis based on near-full-length small subunit and D2-D3 expansion segments of large subunit of ribosomal RNA gene sequences suggested that the species belongs to Acrostichus. The highly derived feeding characters of the new species accentuates the plasticity of the feeding structures of diplogastrid nematodes. In addition to the species description, the generic characters of Acrostichus are emended, and a list of the species in the genus is provided.

A new species of the catfish genus <em>Cambeva</em> from the Paranapanema river drainage, southeastern Brazil (Siluriformes: Trichomycteridae)

The recently described catfish trichomycterid genus Cambeva comprises about 25 valid species, occurring mostly in river basins of south-eastern and southern Brazil. Fifteen species are endemic to the Paraná river basin, of which three are endemic to the Paranapanema river drainage. Herein we describe a fourth new species, Cambeva guareiensis n. sp., known only from the Guareí river. Cambeva guareiensis is similar to C. brachykechenos, C. cubataonis, C. diabola, C. davisi, C. diatropoporos, C. pascuali, C. poikilos and C. stawiarski by having a colour pattern consisting of dark brown spots scattered on the flank and can be differentiated by an exclusive combination of characters, including: the shape of the autopalatine; number of branchiostegal, anal-fin, dorsal-fin, dorsal and ventral caudal procurrent, and pectoral-fin rays; number of interopercular and opercular odontodes; number of vertebrae; and, insertion of anal fin, pelvic fin and urogenital papillae. This study indicates the potential for discovering a greater still unknown trichomycterid species diversity in the Paraná river basin.

Influence of prolonged cultivation on sexual characteristics of sterilized female tilapia, Oreochromis mossambicus, induced by high-temperature treatment

Tilapia represent an important commercial fish for aquaculture. The sterilization of this species is expected to not only promote efficient cultivation and improve flesh quality, but can additionally reduce negative impacts on local environments resulting from the unintentional escape of stock. Although the induction of triploidy is widely used for sterilization in tilapias, triploid tilapia retain their germ cells, which has led to concerns that fertility may persist. A recent study successfully induced sterility in tilapias by implementing only a high-temperature water treatment (HT) in fry stages for a period of 45 days or longer. The present study extends this work by verifying the continued sterility following treatment when cultivation is continued for more than 19 months. We confirmed that high-temperature water treated females had germ cell-deficient gonads based on the histological observation and vasa transcript expression. Although immunohistochemistry against steroidogenic enzymes in the treated gonads revealed that each steroid-producing cell functioned normally, plasma sex steroid hormone levels in treated tilapia were significantly lower than control. Furthermore, the genital papillae in treated females were noticeably undeveloped, suggesting their possible use as an indicator of sterility. Overall, we concluded that sterilization in female tilapia via HT is “permanent”, and HT represents a potential alternative to induced triploidy for enforcing sterility in the aquaculture industry.

A new Hemigrammus from the upper Río Vaupés, Colombia (Characiformes: Characidae), with a discussion on the presence of an enlarged urogenital papilla in the family.

Hemigrammus xaveriellus sp. nov. is described from the upper Río Vaupés basin (Amazon basin), Departamento Guaviare, Colombia. It is distinguished from all congeners by the combination of the following characters: presence of a conspicuous, dark, longitudinal midlateral stripe extending along the body; presence of a conspicuous rounded, horizontally elongated humeral blotch anterior to the beginning of the dark midlateral stripe; seven scale rows between the dorsal fin and lateral line (vs. five to six); and five scale rows between the lateral line and pelvic-fin insertion (vs. three to four). The single mature male of He. xaveriellus possessed a well-developed urogenital papilla, an unusual feature among characids. The presence of an enlarged urogenital papilla in the family is discussed, and comments regarding the putative relationships of the new species are presented.

Amphimermis enzoni n. sp. (Nematoda: Mermithidae) parasitizing damselflies and dragonflies in Argentina.

A mermithid nematode was found parasitizing nymphs of dragonflies and damselflies. The host specimens were collected from the stream Cajaravilla, Magdalena, Buenos Aires state, Argentina. In this work, we described Amphimermis enzoni n. sp., a nematode new to science. Nematodes were identified through morphological and molecular methods. The combination of the following characters separates A. enzoni n. sp. from other members of the genus Amphimermis Steiner: long and S-shaped vagina, twisted spicules for proximal 34% of their length, untwisted for 12%, again twisted for 30%, and untwisted for the last 24%; genital papillae arranged in three rows, medial row marginally longer than sub-medial rows; medial row bifurcated immediately anterior and posterior to cloaca, with 111 genital papillae (73 pre-anals and 38 post-anals). The sequences of 18S rDNA regions from A. enzoni formed a well-supported monophyletic clade with two GenBank sequences of Amphimermis spp. (EF617354 and EF617355) with 0.63 to 1.26% divergence and two Mermithidae spp. (LC512371 and LC512370) with 0.63 to 1.1% divergence, respectively. To our knowledge, this is the first example of mermithid infection in nymphs of dragonflies and damselflies for South America.

Morphological, morphometrical, and molecular characterization of Metarhabditis amsactae (Ali, Pervez, Andrabi, Sharma and Verma, 2011) Sudhaus, 2011 (Rhabditida, Rhabditidae) from India and proposal of Metarhabditis longicaudata as a junior synonym of M. amsactae.

A new population of Metarhabditis amsactae from India is morphologically, morphometrically, and molecularly characterized. This material is characterized by having 0.65 to 1.14 mm length, lips rounded, and grouped in pairs, stoma with metastegostoma bearing setose denticles, pharynx with metacorpus slightly swollen and fusiform, nerve ring, and excretory pore located at isthmus level, female reproductive system didelphic-amphidelphic with vulva equatorial, female tail conical-elongate with acute tip, male tail conical with large and robust posterior filiform part, spicules free with hooked manubrium slightly bent ventrad, gubernaculum with narrow corpus, bursa open leptoderan with eight genital papillae and phasmids posterior to the GP8. Molecular studies based on 18S and 28S rDNA genes are provided for the first time for the species. In addition, integrated morphological, morphometrical, and molecular characters are compared with other previous records of the species. According to our analysis, Metarhabditis longicaudata and other material described as different species are proposed as new junior synonyms of M. amsactae.

A teleost structural analogue to the avian bursa of Fabricius.

The bursa of Fabricius is a primary and secondary lymphoid organ considered exclusively present in birds, and studies of this structure have been vital to our current understanding of the adaptive immune system of vertebrates. In this study, we reveal substantial lymphoepithelial tissue in a previously undescribed bursa in Atlantic salmon (Salmo salar), situated caudal to the urogenital papilla of the cloaca and thus analogous to the anatomical placement of the bursa of Fabricius. We investigated three groups of Atlantic salmon at different maturational stages and characterized the structure by applying dissection, radiology, scanning electron microscopy and histological techniques, including immunohistochemistry and in situ hybridization. We found that the epithelial anlage of the salmon cloacal bursa developed into substantial lymphoepithelial tissue and subsequently regressed following sexual maturation. Such a dynamic development is also a key characteristic of the avian bursa. The presence of intraepithelial lymphocytes was concomitant with expression of the leukocyte‐attracting chemokine CCL19, indicative of lymphoid organ functions. We did not observe recombination or gene conversion in salmon bursal lymphocytes at any developmental stage, indicating the absence of primary lymphoid organ functions in contrast to the bursa of Fabricius. However, the possibility of the bursa to trap both enteric and environmental antigens, combined with the presence of several antigen‐presenting cells residing within the lymphoepithelium, suggest the structure has secondary lymphoid organ functions. We present the discovery of a lymphoid organ in Atlantic salmon with striking topographical similarities to that of the bursa of Fabricius in birds. In addition, the age‐dependent dynamics of its lymphoepithelium suggest functions related to the maturation processes of lymphocytes.

Descriptions of spawning of the pouched lamprey (Geotria australis) in tanks and of morphological changes leading up to and following spawning

The anadromous Geotria australis, one of only three lamprey species representing the early agnathan (jawless) stage of vertebrate evolution in Australia and New Zealand, is declining in abundance. Its adults were caught soon after they had entered rivers on their non-trophic upstream migration and maintained in laboratory tanks for 13–15 months through to spawning. As adult G. australis are susceptible to haemorrhagic septicaemia, they were treated prophylactically and maintained in 3-m3 aquaria supplied with a flow-through charcoal filtration system and UV steriliser. Air temperature and the light:dark regime were constantly adjusted to parallel those in the environment. Males developed the very large suctorial disc and gular pouch characteristic of maturity and both sexes matured at the same time as in the wild. While males frequently showed aggressive behaviour towards each other, the same male and female mated on several occasions. The male coiled around the female and, with his urogenital papilla close to the female’s cloaca, twisted and vibrated, leading to egg release. These eggs formed coagulated clusters as in the wild, with many progressing through to the eight-cell stage. Remarkably, numerous G. australis were still alive 95–392 days after the end of the short spawning period, and one male after a further 119 days. Postspawning survival would be facilitated inter alia by extensive proteolysis, reflected in a shortening of the body. The data in this paper emphasise that G. australis is a highly atypical lamprey and provides invaluable information for conserving this declining species.