Period Of Metamorphosis Research Articles

The Composition and Function of Intestinal Microbiota Were Altered in Farmed Bullfrog Tadpoles (Aquarana catesbeiana) during Metamorphosis

The bullfrog Aquarana catesbeiana is one of the main farmed frog species in China, with a low overall survival of farmed bullfrogs from hatching to harvest since bullfrog tadpoles are fragile during the metamorphosis period. The intestinal bacterial community can play crucial roles in animal development; however, little is known about the alteration of the gut microbial community of A. catesbeiana during metamorphosis. The present study used 16S rRNA amplicon sequencing to investigate the intestinal bacterial community in A. catesbeiana at four distinct developmental stages. Moreover, we determined the bullfrog’s body morphological parameters and the intestine histology at different developmental stages. The results showed a reduction in the total length and snout–vent length of A. catesbeiana during metamorphosis. The intestinal microbial composition of A. catesbeiana exhibited variation throughout the process of metamorphosis. The terrestrial stage showed shifts in the bacterial composition compared to the aquatic stages, including a reduction in Bacteroidetes and an increase in Firmicutes. Furthermore, the presence of Prevotella, Bifidobacterium, Leucobacter, Corynebacterium, Bulleidia, Dorea, Robinsoniella, and Clostridium in A. catesbeiana metamorphosis appears to be mainly related to the host’s epithelial cells’ height and total body mass. The results indicated that the intestinal microbial composition changed with the bullfrog–tadpole metamorphosis. The genera of Prevotella, Bifidobacterium, Leucobacter, Corynebacterium, Bulleidia, Dorea, Robinsoniella, and Clostridium might be potential probiotics.

Emerging from the Covid-19 Cocoon

Since March 2020, teaching and learning in UK higher education has undergone a period of metamorphosis. With campus closures, lecturers and tutors could no longer rely on the teaching and learning style honed over years of in-person delivery. Despite the initial uncertainty of transformation, academic staff have adapted to the new situation, embracing new technology to assist lecture recording, seminar delivery and meetings with colleagues and students. Many will feel that they have become different teachers. Perhaps even, improved teachers, able to work in unique ways and address new challenges. For a while it appeared that teaching in higher education had been completed altered as a result. Yet student voices continue to advocate for in-person delivery. Can, and should, lecturers and tutors revert to their ‘old’ pedagogy, when the opportunity arises to return fully to the lecture theatre, classroom, or laboratory? Or have we emerged from the Covid-19 cocoon completely, and permanently, altered? This article reflects on my own experiences, based on returning to exclusively face-to-face delivery from September 2022, after two and a half years of online and blended learning.

The differential expression and effects of Drosha on metamorphosis of Japanese flounder (paralichthys olivaceus)

Drosha is critical for producing mature microRNAs (miRNAs) from their precursor molecules and small interfering RNAs (siRNAs). Although Drosha has been well characterized in most vertebrate species, identifying the Japanese flounder Drosha has remained elusive. In this study, we cloned the Japanese flounder Drosha gene, which has 4,122 nucleotides (nt), including a 5’-untranslated region (UTR) of 14 nt, a 3’-UTR of 230 nt, and a 3,879 nt open reading frame (ORF) encodes a 1,292 amino acid polypeptide. Then, we analyzed the conservation and phylogenetic evolution of Drosha in some species. Real-time quantitative PCR revealed that Drosha mRNA is highly expressed in the brain, and a lower amount of mRNA was also found in muscle than in other tissues. Drosha plays a vital role in controlling flounder development and metabolism, and its mRNA levels were relatively high at 36 dph (days post-hatching) in the period of metamorphosis and growth of the Japanese flounder. Drosha expression showed in advance with a peak at 23 dph following TH (thyroid hormone) treatment. To further investigate the role of Drosha in metamorphosis, we performed siRNA knockdown of Drosha in flounder embryonic cells (FEC) cells. The result shows that the Drosha-specific siRNA significantly down-regulated Drosha mRNA and miR-1,133,17,214,181a,181b levels, while primary miRNA (pri-miRNA) levels were not significantly different from negative control (NC). These results suggest that Drosha plays a vital role in Japanese flounder development and metamorphosis through processing to produce mature miRNAs, providing essential information for further studying of the part of the Drosha gene in the Japanese flounder development.

Larval rearing of orange mud crab, Scylla olivacea: improving survival rate and shortening metamorphosis period

Orange mud crab (Scylla olivacea) is an important aquaculture species in Southeast Asian countries, especially in the Southwest costal region of Bangladesh. Due to unavailability of hatchery produced seeds the farming of S. olivacea in exclusively depends on the wild for small juveniles resulting in exploitation of this species in Bangladesh. The development of proper hatchery techniques considering better understandings related to larval development are needed to increase the survival and growth rate of S. olivacea in hatchery conditions. Therefore, this study aimed to optimize the water treatment strategy for the upgrading of water quality, minimizing mortality and shortening the metamorphosis duration during larval rearing of mud crab. Newly hatched larvae were reared in three different rearing conditions where the water was treated with both prebiotic (Super-TCT-Biotic, 5 ppm) and probiotics (Fish probiotic, 0.5 ppm) in treatment-1 (T1) but only prophylaxis (mixure of 0.025 ppm Teflan and 0.3 ppm Furazolidone) in treatment-2 (T2). In treatment-3 (T3), prebiotic (5 ppm) and probiotics (0.5 ppm) were combinedly used during first 10 days and prophylaxis (0.3 ppm) was also used from day 14 to day 25. The stocking density was maintained as 50 zoea.L-1 and rotifer, liquid rotifer, enriched Artemia and liquid Artemia were used as feed for the larval growth. The findings revealed that hydrological parameters viz., temperature, salinity, pH, dissolved oxygen and ammonia in all the treatments were similar and found within the acceptable ranges for mud crab larvae rearing. The value of larval stage index (LSI) was found significantly higher (p<0.05) on 21st day of rearing in T3 (6.87±0.06) than T1 (6.74±0.04) and T2 (6.61±0.07). Between, zoea1 and crablet phase, the significantly higher survival rate was observed in T3 (7.00±1.00) than T1 (5.00±0.00) and T2 (4.00±1.00). The result of the present study suggested that combined water treatment with prebiotic, probiotic and prophylaxis can shorten the metamorphosis period and enhance the survival rate of S. olivacea.

Cicero’s Political Personae, by Joanna Kenty, Cambridge: Cambridge University Press

Cicero’s Political Personae is a study of the characters Cicero crafted, embodied, and performed in his postexile speeches. By proxy, it is also a study of oratory from the end of the Roman Republic to the beginning of the Principate, a period of political metamorphosis that author Joanna Kenty notes is more often studied by military historians than by rhetoricians. Kenty’s readings of Cicero’s speeches contextualize the place of orators in this era, and in turn assert orators’ value as negotiators of and with power and as shapers of the Roman political landscape, even during a period of waning republican power (16).Kenty’s project is a rhetorical one insofar as her objects of study are Cicero’s speeches, though her readings intentionally lack a theoretical framework and are not grounded in classical rhetorical theory. There is no mention of a “middle style,” for example, and discussions of rhetorical figures are rare. The absence of theoretical framing may cause rhetoricians to bristle. However, this absence offers an opportunity to read Cicero outside of traditional, often restrictive, classical rhetorical models, models that Cicero himself helped to generate and uphold.Underlying Kenty’s work is the notion that successful speeches are not solely ones by which the rhetor persuades an audience or enacts something tangible. Indeed, Kenty focuses not on the strategies Cicero used to win arguments but rather on the mechanisms by which he engaged in self-fashioning and the purposes served by his invented personae. Many of Cicero’s postexile speeches allude to his shifting place in politics, and the self-fashioning evident in these speeches aims for a delicate diplomatic balance. For example, chapter 2, “The Orator as Friend,” primarily explores Cicero’s persona as friend to Pompey and Caesar. Most intriguing in this chapter is Kenty’s comparison of Cicero’s friend persona in Pro Marcello, in which he praised then-dictator Caesar for allowing the senate to debate Marcellus’s exile, with his persona in parts of the First Philippic, in which he strongly cautioned consuls Antony and Dolabella to take care of the people of Rome—by all accounts, two very different speeches. Throughout Cicero’s Political Personae, Kenty links seemingly unrelated speeches by their shared personae, which allows for a uniquely complex and comprehensive cross-section of Cicero’s later work.Kenty occasionally mentions contemporary politics, though there is ample potential here for reading this text as part of a larger project in classical rhetorical reception. In particular, chapter 6, “The Popular Orator,” which centers on Cicero’s insistence that he was popular despite not being a popularis (i.e., a demagogue), might be read alongside discussions of present-day demagoguery. On a whole, Kenty resists the narrative that oratory declined in the transitional period between the Republic and early Principate by reading Cicero’s postexile speeches both broadly and deeply, and invites us to reconsider the measures by which we determine what is effective oratory.

Characterization of Insulin-Like Growth Factor Binding Protein 7 (Igfbp7) and Its Potential Involvement in Shell Formation and Metamorphosis of Pacific Abalone, Haliotis discus hannai.

Insulin-like growth factor binding proteins (IGFBPs) are secreted proteins that play an important role in IGF regulation of growth and development of vertebrate and invertebrates. In this study, the IGFBP7 gene was cloned and characterized from mantle tissues of H. discus hannai, and designated as Hdh IGFBP7. The full-length cDNA sequence transcribed from the Hdh IGFBP7 gene was 1519-bp long with an open reading frame of 720-bp corresponding to a putative polypeptide of 239 amino acids. The molecular mass of its mature protein was approximately 23.44 KDa with an estimated isoelectric point (pI) of 5.35, and it shared significant homology with IGFBP7 gene of H. madaka. Hdh IGFBP7 has a characteristic IGFBP N-terminal domain (22–89 aa), a kazal-type serine proteinase inhibitor domain (77–128), and an immunoglobulin-like C2 domain (144–223). Furthermore, twelve cysteine residues and a signature motif of IGFBPs (XCGCCXXC) were found in its N-terminal domain. Phylogenetic analysis revealed that Hdh IGFBP7 was aligned with IGFBP7 of H. madaka. Tissue distribution analysis showed that the mRNA of Hdh IGFBP7 was expressed in all examined tissues, with the highest expression level observed in the mantle and gill tissues. The expression level of Hdh IGFBP7 mRNA was relatively higher at the juvenile stage during its metamorphosis period. In situ hybridization showed that Hdh IGFBP7 transcript was expressed in epithelial cells of the dorsal mantle pallial and mucus cells of the branchial epithelium in gill. These results provide basic information for future studies on the role of IGFBP7 in IGF regulation of shell growth, development and metamorphosis of abalone.

Virtualización de la educación superior: Una ventana para la internacionalización en la Universidad Yacambú

La educación tiene un rol fundamental en el desarrollo de la sociedad, siendo uno de los motores de su evolución y progreso. En las últimas décadas, las tecnologías de información y comunicación han provocado grandes cambios en la forma que los individuos se comunican e interactúan, generando verdaderas rupturas en los modos de aprender, enseñar, descubrir, construir y reproducir el conocimiento, situación que ha llevado a formular interrogantes sobre la pertinencia de los sistemas educativos. Dentro de este marco, las universidades transitan un período de metamorfosis, a fin de lograr pertinencia con el entorno, en esta difícil tarea procesos como la virtualización e internacionalización abren nuevas oportunidades y expanden sus posibilidades de desarrollo. La virtualización camina de la mano con la internacionalización, por cuanto la educación virtual constituye una herramienta esencial para ofertar programas en un contexto global, abriendo paso a las alianzas, movilidad académica, internacionalización del currículo, participación en redes de colaboración; acciones que favorecen el posicionamiento y competitividad. La Universidad Yacambú siempre a la vanguardia, ha decido ofrecer respuestas a esta realidad trabajando para consolidar una institución de vanguardia, capaz de apoyar la transformación social en la búsqueda del desarrollo sostenible.

Effects of triclosan on early development of Solea senegalensis: from biochemical to individual level

Harmful effects of triclosan (TCS) have been reported on several organisms; however, effects on early life stages of marine vertebrates are limited. Therefore, the objective of this work was to assess the effects of TCS during early development of the flatfish Solea senegalensis after initial characterization of cholinesterases (ChEs) and determination of selected biochemical markers baseline levels.Characterization of ChEs and determination of biochemical markers baseline levels of cholinergic activity, energy metabolism and oxidative stress were analysed in sole at 3 days after hatching (dah) and at the onset and end of metamorphosis. To assess TCS effects, fish were exposed during 96h to 30-500 μg L−1 TCS until 3 dah. Fish at 13 dah were exposed during 48h to 200-1,500 μg L−1 TCS and maintained until complete metamorphosis. Effects on survival, malformations, length, metamorphosis progression and biochemical markers were evaluated.The main ChE active form present in sole early life stages is acetylcholinesterase and baseline levels of oxidative stress and energy metabolism biomarkers changed according to fish developmental stage. Triclosan induced malformations (EC50 = 180 μg L−1 at 3 dah), decreased growth (95 μg L−1 at 3 dah; 548 μg L−1 at 24 dah) and affected metamorphosis progression (391 μg L−1 at 17 dah). Impairment of antioxidant system was observed, with TCS affecting catalase at the end of metamorphosis test, however, no oxidative damage on lipids was detected. Glutathione S-transferase was the most sensitive endpoint during early larval test (LOEC = 30 μg L−1).Exposure to TCS affected S. senegalensis at individual and sub-individual levels, both at early larval stage and during the critical period of metamorphosis.

Larval exposure to environmentally relevant concentrations of triclosan impairs metamorphosis and reproductive fitness in zebrafish

Developmental exposure to endocrine disruptors can cause organizational changes resulting in latent and transgenerational disease. We exposed zebrafish to environmentally relevant concentrations of triclosan during the critical period of metamorphosis and somatic sex differentiation to determine effects on metamorphosis and reproduction. We use biological and morphological biomarkers to predict potential modes of action. Larval exposure to environmentally relevant concentrations of triclosan was sufficient to cause adverse effects in adults and their offspring. TCS exposure delays metamorphosis and impairs fecundity and fertility. Offspring from TCS-exposed fish show decreased survival and delayed maturation, but their reproductive capacity is not altered. Delays in metamorphosis in conjunction with morphological indicators suggest that toxicity may result from lowered thyroid hormones in parental fish. This work illustrates the importance of evaluating the latent effects of early exposure to environmental contaminants, and that further studies to evaluate the effects of triclosan on the thyroid axis are warranted.

The organophosphate pesticide -OP- malathion inducing thyroidal disruptions and failures in the metamorphosis of the Senegalese sole, Solea senegalensis

BackgroundOrganophosphate pesticides-OP-, like malathion, can alter the normal functioning of neuro-endocrine systems (e.g., hypothalamus-pituitary-thyroid-HPT- axis), and to interfere on the thyroidal homeostasis. Through direct interactions with thyroid receptors, an/or indirectly via up-stream signalling pathways, from the HPT axis (i.e., negative feedback regulation), malathion possess the ability to affect integrity of thyroidal follicular tissue, and it can also block or delay its hormonal functioning. This insecticide can alter the majority of the ontogenetic processes, inducing several deformities, and also provoking decreases in the growth and survival patterns. The present study has been performed to determine the sublethal effects of malathion during the first month of life of the Senegalese sole, Solea senegalensis, and it is mainly focused on the metamorphosis phase. Different transcript expression levels (i.e. thyroid receptors, matrix and bone -Gla-proteins) and immunohistochemical patterns (i.e. thyroid hormones, osteocalcin, cell proliferation) have been analysed during the most critical phases of the flatfish metamorphosis, that is, through differentiation of thyroid system and skeletal development, migration of the eye, and further adaptation to benthic behaviours.ResultsIn early life stages of the Senegalese sole, the exposure to the highest concentration of malathion (6.25 μg/L) affected to the growth patterns, showing the exposed individuals, a reduction around 60 and 92% of the total length and the dry weigth, respectively. In paralell, a significant reduction of the thyroid follicles (i.e., size and number) it was also been recorded, in a dose-dependent way. Abnormal phenotypes induced in the exposed larvae, did not complete the process of metamorphosis, and displayed several morphological abnormalities and developmental disorders, which were mainly associated with the eye migration process, and with thyroidal and skeletal disorders (i.e., transcriptional and protein changes of thyroid hormones and receptors, and of matrix and bone Gla proteins distribution), that conduced to an inadequate adaptation to the benthic life.ConclusionsIn the Senegalese sole, the majority of the ontogenetic alterations induced by the exposure to malathion were mainly associated to the metamorphosis period, which is a thyroid-driven proccess. In fact, most crucial and transitional ontogenic events, appeared notably disturbed, for e.g., thyroid gland differentiation and functioning, migration of eye, skeletal development and benthonic behaviors.

A novel type of prolactin expressed in the bullfrog pituitary specifically during the larval period

Prolactin (PRL) is one of the major hormones that control amphibian metamorphosis. Recently, a PRL (PRL1B) gene that is different from the known PRL (PRL1A) gene has been found in the genomes of several amphibian species. In order to ascertain whether the PRL1B gene is expressed in the bullfrog (Rana catesbeiana) pituitary, cloning of cDNA encoding PRL1B in the pituitary of the premetamorphic bullfrog tadpole was attempted. The bullfrog PRL1B amino acid sequence predicted from the obtained cDNA showed 62% identity with those of Xenopus PRL1Bs that have been presumed from the genome sequences, whereas the sequence identity between bullfrog PRL1A and PRL1B was 48%. A molecular phylogenetic tree showed that bullfrog PRL1B is most appropriately grouped with amphibian PRL1Bs. Quantitative PCR analysis revealed that the mRNA expression levels of bullfrog PRL1B in the pituitary were high during pre- and prometamorphosis, sharply declined at metamorphic climax and became undetectable after metamorphosis. In contrast, PRL1A mRNA levels were relatively low during pre- and prometamorphosis, rose at climax and remained high after metamorphosis. Immunohistochemical study using antibodies against partial peptides of PRL1A and PRL1B revealed that most of the PRL1A- and PRL1B-immunoreactive cells in the larval pituitary were distributed separately, but that some of the cells immunoreactive with both antibodies were also present. Western blot analysis with the larval pituitary extract indicated that PRL1B-immunoreactive band appeared at the position of molecular weight ca. 22.1 kDa and PRL1A-immunoreactive band at the position of ca. 22.8 kDa. The results obtained in this experiment suggest the possibility that PRL1B plays as-yet-unknown role(s) during the pre-climactic period of metamorphosis. This is the first report on the existence of PRL1B as a protein in the amphibian larval pituitary.

Remodeling of peripheral nerve ensheathment during the larval-to-adult transition in Drosophila.

Over the course of a 4-day period of metamorphosis, the Drosophila larval nervous system is remodeled to prepare for adult-specific behaviors. One example is the reorganization of peripheral nerves in the abdomen, where five pairs of abdominal nerves (A4-A8) fuse to form the terminal nerve trunk. This reorganization is associated with selective remodeling of four layers that ensheath each peripheral nerve. The neural lamella (NL), is the first to dismantle; its breakdown is initiated by 6 hours after puparium formation, and is completely removed by the end of the first day. This layer begins to re-appear on the third day of metamorphosis. Perineurial glial (PG) cells situated just underneath the NL, undergo significant proliferation on the first day of metamorphosis, and at that stage contribute to 95% of the glial cell population. Cells of the two inner layers, Sub-Perineurial Glia (SPG) and Wrapping Glia (WG) increase in number on the second half of metamorphosis. Induction of cell death in perineurial glia via the cell death gene reaper and the Diptheria toxin (DT-1) gene, results in abnormal bundling of the peripheral nerves, suggesting that perineurial glial cells play a role in the process. A significant number of animals fail to eclose in both reaper and DT-1 targeted animals, suggesting that disruption of PG also impacts eclosion behavior. The studies will help to establish the groundwork for further work on cellular and molecular processes that underlie the co-ordinated remodeling of glia and the peripheral nerves they ensheath. © 2017 Wiley Periodicals, Inc. Develop Neurobiol 77: 1144-1160, 2017.

Feeding behavior and capture success of turbotPsetta maximalarvae during the transition from upright to tilted swimming position

Aquaculture production of high-quality marine fish larvae might be hampered by poor success in larval initiation of exogenous feeding or the lack of appropriate live feed in their first feeding period. The period of larval metamorphosis may further constrain the successful rearing of flatfish larvae. In order to ascertain changes in feeding during metamorphosis of flatfish, we here compared feeding behavior when larvae of turbot Psetta maxima were either swimming upright or tilted. Using video recordings, we compared the attack rate and prey capture success between flexion (12–13 days-post-hatch, stage 4b–4c) swimming predominantly in upright position and post-flexion (16–17 days-post-hatch, stage 5a–5b) larvae in tilted swimming mode. Both larval groups were fed on copepod nauplii and copepodites. Our results showed a capture success of <50% during the flexion stage, increasing to 73% in the post-flexion stage, and larvae were more successful when feeding on nauplii than when offered copepodite stages. An ontogenetic shift from intermittent to cruise swimming was observed during the metamorphosis concomitant with improved hunting skills. Thus larvae appeared to be able to successfully complete metamorphosis without compromising their feeding ability on copepod prey.

Development of Erythroid Progenitors under Erythropoietin Stimulation in Xenopus laevis Larval Liver.

Erythroid progenitors that respond to erythropoietin (Epo) are present in the liver of adult Xenopus laevis. However, cells responding to Epo in the larval liver and through the metamorphosis period under hepatic remodeling have not been characterized. In this study, tadpoles were staged using the tables of Nieuwkoop and Faber (NF). Liver cells from pre- (NF56) or post- (NF66) metamorphic stage were cultured in the presence of Epo. β2-globin mRNA expression peaked at day 7 after the start of culture. Larval β2-globin was highly expressed in NF56-derived cells, while adult β2-globinwas detected in those of NF66. In both NF56- and NF66-derived cells, mRNA expression of eporand gata2 peaked at day 5 and days 3-4, respectively. In contrast, gata1 expression peaked at day 6 in NF56 cells and at day 5 in NF66 cells. Half maximal proliferation of erythrocytic blast cells derived from the liver at NF66 was observed at day 3, which was earlier than that of NF56. These results indicate that erythroid progenitors that respond to Xenopus laevis Epo are maintained in pre- and post-metamorphic liver, although the tissue architecture changes dramatically during metamorphosis. Additionally, the globin switching occurred, and/or the erythroid progenitors for larval erythrocytes were replaced by those for adult erythrocytes in the metamorphic liver.

Lethal and sublethal effects of a methomyl-based insecticide in Hoplobatrachus rugulosus.

The aim of this study was to investigate the lethal and sublethal toxicity of a methomyl-based insecticide in Hoplobatrachus rugulosus, as methomyl-based insecticides are applied in massive amounts and agrochemicals have effects on the decline in amphibian populations. To evaluate the toxic effects of methomyl from agricultural application, a methomyl-based insecticide containing 40% methomyl was selected. The median lethal concentration of 96 hours of methomyl exposure was 8.69 ppm for H. rugulosus tadpoles. The lethal concentration also produced severe histological damage in the livers and kidneys of the exposed tadpoles. The sublethal concentration used for methomyl was 144 ppb during the metamorphosis period. It was found that the sublethal concentration of the methomyl compound could decrease growth, metamorphosis time, and size, disturb biochemical parameters, and produce histological damage. In livers, methomyl effects increased oxidative stress and dramatically decreased the glycogen level of the treated froglets. Mononuclear infiltration, blood congestion, amorphous substances, and hepatocytes vacuolization were observed throughout liver tissue. The methomyl-based insecticide also increased oxidative stress and decreased nitric oxide levels in the kidneys of the exposed froglets. Renal tissue damage including blood congestion, amorphous substances, and Bowman’s capsule spaces reduction were found in the methomyl exposure group. The methomyl compound also produced vacuoles in various stages of oocytes, but no histological damage was found in testicular tissue. Our results indicated strong toxic effects of the methomyl-based insecticide on H. rugulosus, a broadly tolerant anuran.

DHb9 expressing larval motor neurons persist through metamorphosis to innervate adult-specific muscle targets and function in Drosophila eclosion.

The Drosophila larval nervous system is radically restructured during metamorphosis to produce adult specific neural circuits and behaviors. Genesis of new neurons, death of larval neurons and remodeling of those neurons that persistent collectively act to shape the adult nervous system. Here, we examine the fate of a subset of larval motor neurons during this restructuring process. We used a dHb9 reporter, in combination with the FLP/FRT system to individually identify abdominal motor neurons in the larval to adult transition using a combination of relative cell body location, axonal position, and muscle targets. We found that segment specific cell death of some dHb9 expressing motor neurons occurs throughout the metamorphosis period and continues into the post-eclosion period. Many dHb9 > GFP expressing neurons however persist in the two anterior hemisegments, A1 and A2, which have segment specific muscles required for eclosion while a smaller proportion also persist in A2-A5. Consistent with a functional requirement for these neurons, ablating them during the pupal period produces defects in adult eclosion. In adults, subsequent to the execution of eclosion behaviors, the NMJs of some of these neurons were found to be dismantled and their muscle targets degenerate. Our studies demonstrate a critical continuity of some larval motor neurons into adults and reveal that multiple aspects of motor neuron remodeling and plasticity that are essential for adult motor behaviors. © 2016 Wiley Periodicals, Inc. Develop Neurobiol 76: 1387-1416, 2016.

Morphogenesis of sense organs and behavioural changes in larvae of the brown-marbled grouper Epinephelus fuscoguttatus (Forsskål)

The morphogenesis of sense organs and related behavioural changes in the hatchery-reared brown-marbled grouper Epinephelus fuscoguttatus larvae were examined to gain better understanding of its early life history because ecological field observations for grouper species is difficult. The newly hatched larvae (2.1 mm total length) had developing eyes and otic vesicles, a pair of free neuromast on the head and ciliated olfactory epithelium. At 3 days post hatching (dph), the eyes became fully pigmented with pure-cone retinae, the semicircular canals formed in the inner ear, and the larvae (2.8 mm) were able to swim horizontally, preying on rotifers. Retinal rods and the intra-oral taste buds at pharyngeal appeared next. The olfactory lamellae and the head lateral line system then formed, and the inner ears developed completely in the larvae during the metamorphosis period (15–40 dph; 5.1–18.1 mm). At settlement (50 dph; 32.8 mm), the fish possessed taste buds in the mouth entrance region, and the lateral line system developed completely. The sensory development correlates well with the known aspects of its life history at sea whereby the larvae can feed early and avoid predators during the passive drift, are able to swim shoreward to search nursery ground along the metamorphosis stage and survive in seagrass beds at settlement.

Molecular cloning, expression profiles and promoter analysis of insulin-like growth factor binding protein-4 (IGFBP-4) in Japanese flounder (Paralichthys olivaceus)

We cloned and characterized cDNA sequence of insulin-like growth factor binding protein-4 (IGFBP-4) from Japanese flounder (Paralichthys olivaceus). The 1493 bp full-length cDNA sequence contained an open reading frame (ORF) of 780 bp, which encoded a protein of 259 amino acids. The deduced amino acid sequences included a putative signal peptide of 28 amino acid residues resulting in a mature protein of 231 amino acids. Twenty cysteine residues and two conserved IGFBPs motif (GCGCCXXC and CWCV) were found in the N- and C-terminal domain. In the over 13 kbp genomic sequence, four exons, three introns, and 5'-/3'-flanking sequences were identified. Sequence alignment and phylogenetic analysis showed that Japanese flounder IGFBP-4 was indeed the ortholog of the human IGFBP-4 gene and shared high identities with other teleost IGFBP-4 genes. The promoter region was also analyzed and several potential transcription factor (TF) binding sites were determined which may modulate the IGFBP-4 expression. Quantitative real-time PCR analysis revealed that IGFBP-4 mRNA was observed in various tissues, with intestine showing the highest expression. The maternal transcripts of IGFBP-4 gene existed in the early embryonic stages and then increased in the following stages until hatching, suggesting that IGFBP-4 may be involved in the fish early development. The expression level of IGFBP-4 mRNA was relatively higher at 3 days post hatching (dph) and 15 dph, and gradually decreased during the metamorphosis period. All these results indicated that IGFBP-4 plays a significant role in IGF regulating vertebrate growth and development.

Ontogeny of redox regulation in Atlantic cod (Gadus morhua) larvae

The reduction potential of a cell is related to its fate. Proliferating cells are more reduced than those that are differentiating, whereas apoptotic cells are generally the most oxidized. Glutathione is considered the most important cellular redox buffer and the average reduction potential (Eh) of a cell or organism can be calculated from the concentrations of glutathione (GSH) and glutathione disulfide (GSSG). In this study, triplicate groups of cod larvae at various stages of development (3 to 63 days post-hatch; dph) were sampled for analyses of GSSG/2GSH concentrations, together with activities of antioxidant enzymes and expression of genes encoding proteins involved in redox metabolism. The concentration of total GSH (GSH+GSSG) increased from 610±100 to 1260±150 μmol/kg between 7 and 14dph and was then constant until 49dph, after which it decreased to 810±100μmol/kg by 63dph. The 14- to 49-dph period, when total GSH concentrations were stable, coincides with the proposed period of metamorphosis in cod larvae. The concentration of GSSG comprised approximately 1% of the total GSH concentration and was stable throughout the sampling series. This resulted in a decreasing Eh from −239±1 to −262±7mV between 7 and 14dph, after which it remained constant until 63dph. The changes in GSH and Eh were accompanied by changes in the expression of several genes involved in redox balance and signaling, as well as changes in activities of antioxidant enzymes, with the most dynamic responses occurring in the early phase of cod larval development. It is hypothesized that metamorphosis in cod larvae starts with the onset of mosaic hyperplasia in the skeletal muscle at approximately 20dph (6.8mm standard length (SL)) and ends with differentiation of the stomach and disappearance of the larval finfold at 40 to 50dph (10–15mm SL). Thus, metamorphosis in cod larvae seems to coincide with high and stable total concentrations of GSH.

China as a Sea Power, 1127-1368: A Preliminary Survey of the Maritime Expansion and Naval Exploits of the Chinese People during the Southern Song and Yuan Periods by Lo Jung-Pang (review)

Reviewed by: China as a Sea Power, 1127-1368: A Preliminary Survey of the Maritime Expansion and Naval Exploits of the Chinese People during the Southern Song and Yuan Periods by Lo Jung-Pang Loh Wei Leng China as a Sea Power, 1127-1368: A Preliminary Survey of the Maritime Expansion and Naval Exploits of the Chinese People during the Southern Song and Yuan Periods Lo Jung-Pang , EDITED BY Bruce A. EllemanSingapore: NUS Press, 2012. 450 pp. ISBN: 978-9971-69-505-7. Paperback This publication on Maritime China was completed in draft form a quarter-century before Lo's untimely demise in 1981. It was, in fact, ready two years after his 1955 article, 'The Emergence of China as a Sea Power during the Late Sung and Early Yuan Periods' in the Far Eastern Quarterly. Indeed, the English language academic community has long had access to Lo's pioneering articles; some essays of relevance to note are 'The Decline of the Early Ming Navy' (Oriens Extremus, 1958) and 'Maritime Commerce and Its Relation to the Sung Navy' (Journal of the Economic and Social History of the Orient, 1969). A host of other articles are listed in Geoff Wade's Introduction (p. 1, n.1), including his papers lodged at the Needham Research Institute in Cambridge (p. 2, n.6), the outcome of his communication with Joseph Needham whose Science and Civilization volumes are seminal works in the field of Chinese Studies. However, from this monograph readers will have the benefit of a full-blown exposition of Lo's findings on the rise of China as a maritime power in the era of China's maritime expansion prior to the more widely known period of the Ming and the Zheng He voyages. Thanks to Bruce Elleman, Research Professor in the Maritime History Department (the US Naval War College), who found the unpublished manuscript in the University of California at Davis archives and took on the task of editing it. Thanks also to Geoff Wade for his historiographical survey of the relevant literature since the 1980s to assist readers to better appreciate Lo's analysis of the historical precedents of China's pre-modern maritime development. This is most timely given China's current emergence as a global economic player, providing her with the wherewithal to become a naval superpower. From the strategic standpoint it has significant implications on the contestation of maritime resources in the South China Sea region and perhaps beyond, in the Pacific, and even towards dominance of other global arenas. The first of the book's four parts traces the factors behind the outward look towards the sea, as opposed to those periods when China was focused on her terrestrial frontiers, particularly in the north. Parts 2 and 3 examine key changes [End Page 132] during the Southern Song and Yuan dynasties, while Part 4 focuses on developments under the Ming. In his Preface, Lo's opening sentence is a forceful pronouncement on what he saw as an important phase of Chinese history, a period of transition to the modern world: The three hundred years from the beginning of the twelfth century to the beginning of the fifteenth was a period of fundamental and profound metamorphosis for China...a time of intellectual ferment and economic conversion and a time of political turmoil and social upheaval (p. xiv). While his main theme focuses on the Chinese navy and its performance, precisely because of the close interconnection with national, geographic, economic and social forces shaping how it functioned, this study provides a lens into the context within which the navy emerged, grew and declined. Chapter 1, 'China's Rise as a Naval Power', is a survey which stretches back to the Chou Dynasty (1046-1043 BCE) when ships were required to transport troops. The narrative takes in attempts, in subsequent centuries BCE, of fleets raised for invasions, countless naval encounters such as those between the states of Wu (in the lower valley of the Yangzi) and Ch'u (in present-day Hubei and Hunan) in the sixth century BCE to the 'first known sea battle in the history of China' (p. 27) in 485 BCE. Crossing into the...