Vertebrate genome evolution and the zebrafish gene map

In chordate phylogeny, changes in the nervous system, jaws, and appendages transformed meek filter feeders into fearsome predators. Gene duplication is thought to promote such innovation. Vertebrate ancestors probably had single copies of genes now found in multiple copies in vertebrates and gene maps suggest that this occurred by polyploidization. It has been suggested that one genome duplication event occurred before, and one after the divergence of ray-finned and lobe-finned fishes. Holland et al., however, have argued that because various vertebrates have several HOX clusters, two rounds of duplication occurred before the origin of jawed fishes. Such gene-number data, however, do not distinguish between tandem duplications and polyploidization events, nor whether independent duplications occurred in different lineages. To investigate these matters, we mapped 144 zebrafish genes and compared the resulting map with mammalian maps. Comparison revealed large conserved chromosome segments. Because duplicated chromosome segments in zebrafish often correspond with specific chromosome segments in mammals, it is likely that two polyploidization events occurred prior to the divergence of fish and mammal lineages. This zebrafish gene map will facilitate molecular identification of mutated zebrafish genes, which can suggest functions for human genes known only by sequence.

Development and maturation of the immune system in zebrafish, Danio rerio: a gene expression profiling, in situ hybridization and immunological study

The development and maturation of the immune system in zebrafish was investigated using immune-related gene expression profiling by quantitative real-time polymerase chain reaction, in situ hybridization (ISH), immunoglobulin (Ig) detection by immuno-affinity purification and Western blotting as well as immersion immunization experiments. Ikaros expression was first detected at 1 day post-fertilization (dpf) and thereafter increased gradually to more than two-fold between 28 and 42dpf before decreasing to less than the initial 1dpf expression level in adult fish (aged 105dpf). Recombination activating gene-1 (Rag-1) expression levels increased rapidly (by 10-fold) between 3 and 17dpf, reaching a maximum between 21 and 28dpf before decreasing gradually. However, in adult fish aged 105dpf, the expression level of Rag-1 had dropped markedly, and was equivalent to the expression level at 3dpf. T-cell receptor alpha constant region and immunoglobulin light chain constant region (IgLC) isotype-1, 2 and 3 mRNAs were detected at low levels by 3dpf and their expression levels increased steadily to the adult range between 4 and 6 weeks post-fertilization (wpf). Using tissue-section ISH, Rag-1 expression was detected in head kidney by 2wpf while IgLC-1, 2 and 3 were detected in the head kidney and the thymus by 3wpf onwards. Secreted Ig was only detectable using immuno-affinity purification and Western blotting by 4wpf. Humoral response to T-independent antigen (formalin-killed Aeromonas hydrophila) and T-dependent antigen (human gamma globulin) was observed in zebrafish immunized at 4 and 6wpf, respectively, indicating that immunocompetence was achieved. The findings reveal that the zebrafish immune system is morphologically and functionally mature by 4-6wpf.

The Arabidopsis HOS1 gene negatively regulates cold signal transduction and encodes a RING finger protein that displays cold-regulated nucleo--cytoplasmic partitioning

Low temperature is one of the most important environmental stimuli that control gene transcription programs and development in plants. In Arabidopsis thaliana, the HOS1 locus is a key negative regulator of low temperature-responsive gene transcription. The recessive hos1 mutation causes enhanced induction of the CBF transcription factors by low temperature as well as of their downstream cold-responsive genes. The hos1 mutant plants flower early, and this correlates with a low level of Flowering Locus C gene expression. The HOS1 gene was isolated through positional cloning. HOS1 encodes a novel protein with a RING finger motif near the amino terminus. HOS1 is ubiquitously expressed in all plant tissues. HOS1--GFP translational fusion studies reveal that HOS1 protein resides in the cytoplasm at normal growth temperatures. However, in response to low temperature treatments, HOS1 accumulates in the nucleus. Ectopic expression of HOS1 in wild-type plants causes cosuppression of HOS1 expression and mimics the hos1 mutant phenotypes.

Modulation of abscisic acid signal transduction and biosynthesis by an Sm-like protein in Arabidopsis

The phytohormone abscisic acid (ABA) regulates plant growth and development as well as stress tolerance. The Arabidopsis sad1 (supersensitive to ABA and drought) mutation increases plant sensitivity to drought stress and ABA in seed germination, root growth, and the expression of some stress-responsive genes. sad1 plants are also defective in the positive feedback regulation of ABA biosynthesis genes by ABA and are impaired in drought stress induction of ABA biosynthesis. SAD1 encodes a polypeptide similar to multifunctional Sm-like snRNP proteins that are required for mRNA splicing, export, and degradation. These results suggest a critical role for mRNA metabolism in the control of ABA signaling as well as in the regulation of ABA homeostasis.

Expression of zebrafish bHLH genes ngn1 and nrd defines distinct stages of neural differentiation

Two zebrafish bHLH genes, neurogenin-related gene I (ngn1) and neuroD (nrd), have been isolated. ngn1 expression is initiated at the end of gastrulation in the neural plate and defines broad domains of cells that probably possess an ability to develop as neurons. This finding suggests that ngn1 may play a role during determination of cell fate in neuroblasts. ngn1 and pax-b are expressed in a mutually exclusive manner. nrd expression follows that of ngn1 in restricted populations of cells selected from ngn1-positive clusters of cells. The earliest nrd-positive cells in the brain and the trunk are a subset of the primary neurons. ngn1 is not expressed in the eye. Here, nrd transcription is activated at 25 hours postfertilization in the ventral retina. Expression of islet-1 occurs in nrd-positive cells after expression of nrd, and the expression of the two genes partially overlaps in time. These observations suggest that during eye development nrd expression may follow expression of some other neurodetermination gene(s). This supports the idea that expression of nrd is a necessary step leading toward overt neuronal differentiation.

Direct evidence for anthocyanidin synthase as a 2-oxoglutarate-dependent oxygenase: molecular cloning and functional expression of cDNA from a red forma of Perilla frutescens

Anthocyanidin synthase (ANS), an enzyme of the biosynthetic pathway to anthocyanin, has been postulated to catalyze the reaction(s) from the colorless leucoanthocyanidins to the colored anthocyanidins. Although cDNAs have been isolated that encode putative ANS, which exhibits significant similarities in amino acid sequence with members of a family of 2-oxoglutarate-dependent oxygenases, no biochemical evidence has been presented which identifies the actual reaction that is catalyzed by ANS. Here we show that anthocyanidins are formed in vitro through 2-oxoglutarate-dependent oxidation of leucoanthocyanidins catalyzed by the recombinant ANS and subsequent acid treatment. A cDNA encoding ANS was isolated from red and green formas of Perilla frutescens by differential display of mRNA. Recombinant ANS tagged with maltose-binding-protein (MBP) was purified, and the formation of anthocyanidins from leucoanthocyanidins was detected by the ANS-catalyzed reaction in the presence of ferrous ion, 2-oxoglutarate and ascorbate, being followed by acidification with HCI. Equimolar stoichiometry was confirmed for anthocyanidin formation and liberation of CO2 from 2-oxoglutarate. The presumptive two-copy gene of ANS was expressed in leaves and stems of the red forma of P. frutescens but not in the green forma plant. This corresponds to the accumulation pattern of anthocyanin. The mechanism of the reaction catalyzed by ANS is discussed in relation to the molecular evolution of a family of 2-oxoglutarate-dependent oxygenases.

Asynchronous activation of 10 muscle-specific protein (MSP) genes during zebrafish somitogenesis

In the present study, 10 zebrafish cDNA clones coding for muscle-specific proteins (MSPs) were characterized and most of them encode fast skeletal muscle isoforms. They are skeletal muscle alpha-actin (acta1), fast skeletal muscle a-tropomyosin (tpma), fast skeletal muscle troponin C (tnnc), fast skeletal muscle troponin T (tnnt), fast skeletal muscle myosin heavy chain (myhz1), fast skeletal muscle myosin light chain 2 (mylz2), fast skeletal muscle myosin light chain 3 (mylz3), muscle creatine kinase (ckm), parvalbumin (pvalb), and desmin (desm). Using these cDNA probes, their expression patterns in developing embryos and adults were compared by Northern blot hybridization and whole-mount in situ hybridization. All of the 10 genes are expressed in both embryos and adult fish, and the expression is highly abundant in skeletal muscle. Among them, acta1, tpma, tnnc, tnnt, myhz1, mylz2, mylz3 and pvalb, are expressed specifically in fast skeletal muscle while ckm and desm are expressed in both fast and slow skeletal muscles. In addition, tpma, ckm, and desm are also expressed in the heart. Ontogenetically, the onset of expression of these MSP genes in zebrafish skeletal muscle varies and the expression occurs rostral-caudally in developing somites. Shortly after the expression of myoD, desm is the first to be activated at approximately 9 hpf, followed by tpma (approximately 10 hpf), tnnc (approximately 12 hpf), acta1 (approximately 12 hpf), ckm (approximately 14 hpf), myhz1 (approximately 14 hpf), mylz2 (approximately 16 hpf), mylz3 (approximately 16.5 hpf), tnnt (approximately 16.5 hpf), and pvalb (approximately 16.5 hpf). At later stages (after 48 hpf), these MSP genes are also expressed in fin buds and head muscles including eye, jaw, and gill muscles. Thus, our experiment demonstrated the order of expression of the 10 MSP genes, which may reflect the sequence of muscle filament assembly. In spite of the asynchrony in activation of these MSP genes, the timing of expression for each individual MSP gene appears to be synchronous to somite development as each somite has an identical timetable to express the set of MSP genes.

Genes that are uniquely stress regulated in salt overly sensitive (sos) mutants

Repetitive rounds of differential subtraction screening, followed by nucleotide sequence determination and northern-blot analysis, identified 84 salt-regulated (160 mM NaCl for 4 h) genes in Arabidopsis wild-type (Col-0 gl1) seedlings. Probes corresponding to these 84 genes and ACP1, RD22BP1, MYB2, STZ, and PAL were included in an analysis of salt responsive gene expression profiles in gl1 and the salt-hypersensitive mutant sos3. Six of 89 genes were expressed differentially in wild-type and sos3 seedlings; steady-state mRNA abundance of five genes (AD06C08/unknown, AD05E05/vegetative storage protein 2 [VSP2], AD05B11/S-adenosyl-L-Met:salicylic acid carboxyl methyltransferase [SAMT], AD03D05/cold regulated 6.6/inducible2 [COR6.6/KIN2], and salt tolerance zinc finger [STZ]) was induced and the abundance of one gene (AD05C10/circadian rhythm-RNA binding1 [CCR1]) was reduced in wild-type plants after salt treatment. The expression of CCR1, SAMT, COR6.6/KIN2, and STZ was higher in sos3 than in wild type, and VSP2 and AD06C08/unknown was lower in the mutant. Salt-induced expression of VSP2 in sos1 was similar to wild type, and AD06C08/unknown, CCR1, SAMT, COR6.6/KIN2, and STZ were similar to sos3. VSP2 is regulated presumably by SOS2/3 independent of SOS1, whereas the expression of the others is SOS1 dependent. AD06C08/unknown and VSP2 are postulated to be effectors of salt tolerance whereas CCR1, SAMT, COR6.6/KIN2, and STZ are determinants that must be negatively regulated during salt adaptation. The pivotal function of the SOS signal pathway to mediate ion homeostasis and salt tolerance implicates AD06C08/unknown, VSP2, SAMT, 6.6/KIN2, STZ, and CCR1 as determinates that are involved in salt adaptation.

Characteristics and antifungal activity of a chitin binding protein from Ginkgo biloba

An antifungal peptide from leaves of Ginkgo biloba, designated GAFP, has been isolated. Its molecular mass of 4244.0 Da was determined by mass spectrometry. The complete amino acid sequence was obtained from automated Edman degradation. GAFP exhibited antifungal activity towards Pellicularia sasakii Ito, Alternaria alternata (Fries) Keissler, Fusarium graminearum Schw. and Fusarium moniliforme. Its activities differed among various fungi. GAFP could also cause increased hyphal membrane permeabilization and a rapid alkalization of the medium when applied at 100 microgram/ml to Pellicularia sasakii Ito hyphae. The amino acid sequence of GAFP shows characteristics of the cysteine/glycine-rich chitin binding domain of many chitin binding proteins. The cysteine residues are well conserved.

Expression pattern of two zebrafish genes, cxcr4a and cxcr4b

We cloned and mapped two novel zebrafish genes, cxcr4a and cxcr4b, which are closely related to mammalian CXCR4. Expression analysis by reverse transcription-polymerase chain reaction and in situ hybridization demonstrated that these two genes are expressed in most cell lineages known to express Cxcr4 in mammals. These genes are co-expressed in lateral mesoderm and posterior midbrain. The transcripts of cxcr4a were detected in interneurons and endoderm, whereas cxcr4b was specifically expressed in sensory neurons, motoneurons and cerebellum. In the lateral mesoderm, cxcr4b transcripts appeared earlier than those of cxcr4a. Thus, the function of mammalian CXCR4 could be split between the two zebrafish genes. These genes probably derived from the genome duplication event, which occurred during the evolution of teleosts. Similar pairs of Cxcr4 may exist in other species, where genome duplication has occurred.

Molecular heterogeneity among primary motoneurons and within myotomes revealed by the differential mRNA expression of novel islet-1 homologs in embryonic zebrafish

Zebrafish embryos have three or four identifiable primary motoneurons per hemisegment. We previously reported that, while several ventral cells initially express the zebrafish Islet-1 (Isl-1) gene, a member of the LIM/homeobox gene family, the expression of this gene becomes restricted to a single or a pair of cells slightly anterior to each segment border by 16 hr after fertilization. Double staining by in situ hybridization and immunohistochemistry strongly suggested that these cells were mainly rostral primary motoneurons. Here, we have isolated two novel zebrafish cDNA clones for more Isl-1 family genes, termed zfIsl-2 and zfIsl-3. zfIsl-2 mRNA starts to be expressed in the ventral midsegmental cells per hemisegment around 15 hr. Double labeling experiments have shown that these midsegmental cells are the caudal primary motoneuron (CaP) and its variant equivalence pair. Our results revealed the heterogeneity in the expressed genes among primary motoneurons before the fates of the primary motoneurons are irreversibly determined, and further suggest the involvement of the Isl-1 and zfIsl-2 genes in the determination of cellular identities by primary motoneurons in embryonic zebrafish. zfIsl-3 mRNA is not expressed in motoneurons but is expressed at 17 hr, mainly in the ventral myotomes. This suggests that zfIsl-3 may be involved in the regional specification of the myotome and also in target recognition by CaP. zfIsl-2 is also expressed throughout the developing eye and tectal region of the midbrain, the target for the retinal axons. In the ventral spinal cord of the spadetail mutant embryo, which has defects in the somites, the cells expressing zfIsl-2 mRNA significantly decreased in number in contrast to the increase in cells expressing Isl-1 mRNA, suggesting the influence of the somites on the expression of both genes.

A zebrafish vitellogenin gene (vg3) encodes a novel vitellogenin without a phosvitin domain and may represent a primitive vertebrate vitellogenin gene

By analysis of zebrafish EST (expressed sequence tag) clones from an adult cDNA library, we have identified 44 clones, about 11% of the adult EST clones, encoding vitellogenins. These vitellogenin EST clones have been derived from at least seven distinct vitellogenin genes. One of the largest vitellogenin cDNA clones, vg3, and its 5' extended clone isolated by 5' RACE (rapid amplification of cDNA ends)-PCR, have been sequenced completely. The deduced complete sequence includes a predicted mature vitellogenin of 1233 amino acids and a truncated signal peptide of 18 amino acids. Interestingly, the predicted vitellogenin has no polyserine phosvitin domain. The lack of the phosvitin domain was confirmed by isolation and sequencing of the vg3 genomic region. Phylogenetic analysis indicates that the phosvitinless vitellogenin is an intermediate between invertebrate vitellogenins and all known vertebrate vitellogenins, and thus may represent a primitive vertebrate vitellogenin. Like other vitellogenins in vertebrates, the phosvitinless vitellogenin is also synthesized mainly in the liver and weakly in the intestine.

Molecular cloning and biochemical characterization of a novel anthocyanin 5-O-glucosyltransferase by mRNA differential display for plant forms regarding anthocyanin

UDP-glucose: anthocyanin 5-O-glucosyltransferase (5-GT) is responsible for the modification of anthocyanins to more stable molecules in complexes for co-pigmentation, supposedly resulting in a purple hue. The cDNA encoding 5-GT was isolated by a differential display applied to two different forms of anthocyanin production in Perilla frutescens var. crispa. Differential display was carried out for mRNA from the leaves of reddish-purple and green forms of P. frutescens, resulting in the isolation of five cDNA clones predominantly expressed in the red form. The cDNA encoded a polypeptide of 460 amino acids, exhibiting a low homology with the sequences of several glucosyltransferases including UDP-glucose: anthocyanidin 3-O-glucosyltransferase. By using this cDNA as the probe, we also isolated a homologous cDNA clone from a petal cDNA library of Verbena hybrida. To identify the biochemical function of the encoded proteins, these cDNAs were expressed in Saccharomyces cerevisiae cells. The recombinant proteins in the yeast extracts catalyzed the conversion of anthocyanidin 3-O-glucosides into the corresponding anthocyanidin 3,5-di-O-glucosides using UDP-glucose as a cofactor, indicating the identity of the cDNAs encoding 5-GT. Several biochemical properties (optimum pH, Km values, and sensitivity to inhibitors) were similar to those reported previously for 5-GTs. Southern blot analysis indicated the presence of two copies of 5-GT genes in the genome of both red and green forms of P. frutescens. The mRNA accumulation of the 5-GT gene was detected in the leaves of the red form but not in those of the green form and was induced by illumination of light, as observed for other structural genes for anthocyanin biosynthesis in P. frutescens.

Faithful expression of green fluorescent protein (GFP) in transgenic zebrafish embryos under control of zebrafish gene promoters

Although the zebrafish has become a popular model organism for vertebrate developmental and genetic analyses, its use in transgenic studies still suffers from the scarcity of homologous gene promoters. In the present study, three different zebrafish cDNA clones were isolated and sequenced completely, and their expression patterns were characterized by whole-mount in situ hybridization as well as by Northern blot hybridization. The first clone encodes a type II cytokeratin (CK), which is specifically expressed in skin epithelia in early embryos and prominently expressed in the adult skin tissue. The second clone is muscle specific and encodes a muscle creatine kinase (MCK). The third clone, expressed ubiquitously in all tissues, is derived from an acidic ribosomal phosphoprotein P0 (arp) gene. In order to test the fidelity of zebrafish embryos in transgenic expression, the promoters of the three genes were isolated using a rapid linker-mediated PCR approach and subsequently ligated to a modified green fluorescent protein (gfp) reporter gene. When the three hybrid GFP constructs were introduced into zebrafish embryos by microinjection, the three promoters were activated faithfully in developing zebrafish embryos. The 2.2-kb ck promoter was sufficient to direct GFP expression in skin epithelia, although a weak expression in muscle was also observed in a few embryos. This pattern of transgenic expression is consistent with the expression pattern of the endogenous cytokeratin gene. The 1.5-kb mck promoter/gfp was expressed exclusively in skeletal muscles and not elsewhere. By contrast, the 0.8-kb ubiquitous promoter plus the first intron of the arp gene were capable of expressing GFP in a variety of tissues, including the skin, muscle, lens, neurons, notochord, and circulating blood cells. Our experiments, therefore, further demonstrated that zebrafish embryos can faithfully express exogenously introduced genes under the control of zebrafish promoters.

Crosstalk of Ras and Rho: activation of RhoA abates Kras-induced liver tumorigenesis in transgenic zebrafish models

RAS and Rho small GTPases are key molecular switches that control cell dynamics, cell growth and tissue development through their distinct signaling pathways. Although much has been learnt about their individual functions in both cell and animal models, the physiological and pathophysiological consequences of their signaling crosstalk in multi-cellular context in vivo remain largely unknown, especially in liver development and liver tumorigenesis. Furthermore, the roles of RhoA in RAS-mediated transformation and their crosstalk in vitro remain highly controversial. When challenged with carcinogens, zebrafish developed liver cancer that resembles the human liver cancer both molecularly and histopathologically. Capitalizing on the growing importance and relevance of zebrafish (Danio rerio) as an alternate cancer model, we have generated liver-specific, Tet-on-inducible transgenic lines expressing oncogenic Kras(G12V), RhoA, constitutively active RhoA(G14V) or dominant-negative RhoA(T19N). Double-transgenic lines expressing Kras(G12V) with one of the three RhoA genes were also generated. Based on quantitative bioimaging and molecular markers for genetic and signaling aberrations, we showed that the induced expression of oncogenic Kras during early development led to liver enlargement and hepatocyte proliferation, associated with elevated Erk phosphorylation, activation of Akt2 and modulation of its two downstream targets, p21Cip and S6 kinase. Such an increase in liver size and Akt2 expression was augmented by dominant-negative RhoA(T19N), but was abrogated by the constitutive-active RhoA(G14V). Consequently, induced expression of the oncogenic Kras in adult transgenic fish led to the development of hepatocellular carcinomas. Survival studies further revealed that the co-expression of dominant-negative RhoA(T19N) with oncogenic Kras increased the mortality rate compared with the other single or double-transgenic lines. This study provides evidence of the previously unappreciated signaling crosstalk between Kras and RhoA in regulating liver overgrowth and liver tumorigenesis. Our results also implicate that activating Rho could be beneficial to suppress the Kras-induced liver malignancies.

Cloning and developmental expression of a family of pleurocidin-like antimicrobial peptides from winter flounder, Pleuronectes americanus (Walbaum)

Low molecular weight antimicrobial peptides are an important component of the innate immune system in animals, yet they have not been examined widely in fish. Of particular interest is their expression during development and in response to environmental conditions and disease. Here, we report the isolation of four genomic sequences encoding putative antimicrobial peptides from the winter flounder, Pleuronectes americanus (Walbaum), as well as reverse transcription-PCR products from two tissues that form the first defensive barrier to microbes - skin and intestine. Alignment of the predicted polypeptide sequences shows a conserved hydrophobic signal peptide of 22 amino acids followed by 25 amino acids that are identical (WF2) or homologous to the amino acid sequence of pleurocidin, followed by a conserved acidic portion. Southern hybridisation analysis indicates that related peptides are encoded in the genomes of other flatfish species. Northern and RT-PCR analyses of RNA from multiple tissues show that two of the pleurocidin genes are expressed predominantly in the skin whereas two other genes are expressed mainly in the intestine. RT-PCR assays of total RNA from larvae of different ages provide the first evidence of developmental expression of antimicrobial peptides in fish and indicate that the pleurocidin gene is first expressed at 13 days post-hatch in winter flounder.

Rapid identification and isolation of zebrafish cDNA clones

A fast and economical approach, referred to as cDNA clone tagging, was adapted to identify and isolate zebrafish cDNA clones. The basic approach was to partially sequence the coding region of size selected cDNA clones and the partial sequences were then used as tags for identifying the clones through homology search. To benefit maximally from the tagging approach, two cDNA libraries, derived from embryonic and adult fish poly(A)+ RNAs, respectively, were constructed by unidirectional cloning; conceptually, they have the potential to represent all expressed zebrafish genes. A total of 1084 clones were sequenced from the two libraries, and 511 clones were identified, based on sequence homology. These identified clones were derived from at least 261 genes, encoding 48 translational machinery proteins, 47 cytosolic proteins, 43 cytoskeletal proteins, 41 nuclear proteins, 32 membrane proteins, 22 secreted proteins, 20 mitochondrial proteins and 8 proteins with an unknown location. Of the 261 distinct cDNA clones identified, 254 were isolated for the first time in the zebrafish. These tagged cDNA clones, identified and unidentified, provide rich resources for developmental analysis as well as mapping of zebrafish genome. The long-term objective of this study is to establish a tagged zebrafish gene library that can be accessed both by hybridization screening against the plasmid DNAs and by electronic screening using the sequence information.

Characterization of two zebrafish cDNA clones encoding egg envelope proteins ZP2 and ZP3

Two zebrafish cDNA clones encoding homologs of mammalian zona pellucida proteins ZP2 and ZP3 were isolated from a whole adult cDNA library. The ZP2 clone encodes a protein of 428 amino acids. Unlike other teleost ZP2s that contain an N-terminal repetitive domain enriched with prolines and glutamines, the zebrafish ZP2 has no such repetitive domain. In the C-terminal non-repetitive domain, the zebrafish ZP2 shares 55-76% sequence identity with other teleost ZP2s. The ZP3 cDNA clone encodes a protein of 431 amino acids, which shares 61% sequence identity with a carp ZP3. Similar to mammalian ZP proteins, both zebrafish ZP2 and ZP3 contain several potential phosphorylation sites. However, unlike mammalian ZP proteins, both zebrafish ZP proteins contain almost no glycosylation site, which has been proposed to be important for interaction with sperm; thus, the ZP proteins may behave differently in mammals and teleosts. Northern blot analysis indicated that both zebrafish ZP2 and ZP3 mRNAs were expressed exclusively in the ovary and hence the ovary is likely the only site for ZP2 and ZP3 biosynthesis.

Cloning and molecular analysis of structural genes involved in anthocyanin biosynthesis and expressed in a forma-specific manner in Perilla frutescens

Two cultivars of Perilla frutescens, red and green formas are known to differ in anthocyanin accumulation in leaves and stems. cDNA clones encoding the enzymes involved in anthocyanin biosynthesis, chalcone synthase (CHS), flavanone 3-hydroxylase (F3H), dihydroflavonol 4-reductase (DFR), and UDP glucose: flavonoid 3-O-glucosyltransferase (3GT), were isolated from cDNA libraries derived from the leaves of a red forma of P. frutescens by screening with partial fragments amplified by means of polymerase chain reaction (PCR) and heterologous cDNAs as probes. The deduced amino acid sequences of these four genes exhibited 40-90% identity with those reported for the corresponding gene from other unrelated species. Southern blot analysis for these genes and two other structural genes, the leucoanthocyanidin dioxygenase (LDOX, anthocyanidin synthase) and anthocyanin acyltransferase (AAT) genes, indicated that each gene comprises a small multi-gene family. More than three copies of the CHS gene are present, two copies of the other genes being present. The expression of five genes, the exception being the CHS gene, was detected only in red leaves of the red forma of P. frutescens, i.e. not in green leaves of the green forma plant. The CHS gene was expressed in both red and green leaves, but 10-fold more in red leaves than in green leaves. These results suggest that the expression of all structural genes examined is coordinately regulated in a forma-specific manner. Under weak-light conditions, the accumulation of both anthocyanin and mRNAs of biosynthetic enzymes was lower in leaves of the red forma. High-intensity white light coordinately induced the accumulation of transcripts of all six genes examined in the mature leaves of red P. frutescens.

Green fluorescent protein (GFP) transgenic fish and their applications

The coupling of the GFP reporter system with the optical clarity of embryogenesis in model fish such as zebrafish and medaka is beginning to change the picture of transgenic fish study. Since the advent of first GFP transgenic fish in 1995, GFP transgenic fish technology have been quickly employed in many areas such as analyses of gene expression patterns and tissue/organ development, dissection of promoters/enhancers, cell lineage and axonal pathfinding, cellular localization of protein products, chimeric embryo and nuclear transplantation, cell sorting, etc. The GFP transgenic fish also have the potentials in analysis of upstream regulatory factors, mutagenesis screening and characterization, and promoter/enhancer trap. Our own studies indicate that GFP transgenic fish may become a new source of novel variety of ornamental fish. Efforts are also being made in our laboratory to turn GFP transgenic fish into biomonitoring organisms for surveillance of environmental pollution.

JWA regulates melanoma metastasis by integrin alphaVbeta3 signaling

JWA, a newly identified novel microtubule-associated protein (MAP), was recently demonstrated to be indispensable for the rearrangement of actin cytoskeleton and activation of MAPK cascades induced by arsenic trioxide (As(2)O(3)) and phorbol ester (PMA). JWA depletion blocked the inhibitory effect of As(2)O(3) on HeLa cell migration, but enhanced cell migration after PMA treatment. As cancer cell migration is a hallmark of tumor metastasis and the functional role of JWA in cancer metastasis is not understood, here we show that JWA has an important role in melanoma metastasis. Our data demonstrated that JWA knockdown increased the adhesion and invasion abilities of melanoma cells. Furthermore, JWA knockdown in B16-F10 and A375 melanoma cells significantly promoted the formation and growth of metastatic colonies in vivo. Moreover, in the tumor biopsies from human melanoma patients, JWA expression was significantly decreased in malignant melanoma compared with normal nevi. In addition, we found that JWA knockdown could intensify tumor integrin alpha(V)beta(3) signaling by regulating nuclear factor Sp1. These findings suggest that JWA suppresses melanoma metastasis and may serve a potential therapeutic target for human melanoma.

Morphologic transformation of the thymus in developing zebrafish

The morphologic transformation of the developing zebrafish thymus from 1 week postfertilization (wpf) to 15 wpf is described. The thymus overall morphology changed from a small pouch-like shape at 1 wpf to a conical shape between 2 and 3 wpf before acquiring a more complex shape from 4 wpf onward. Rapid growth rate along the lateral axis at the region near the pharyngeal epithelium occurred between 1 and 2 wpf, whereas rapid growth rate along the dorsal-ventral axis occurred between 3 and 6 wpf. Expansion of thymocyte population beginning from 1 wpf became more evident by 2 to 3 wpf, as indicated by the apparent increase of different sizes of lymphocytes, recombination activating gene-1 (rag-1), and T-cell antigen receptor alpha chain constant region (TCRAC) -positive cells. Tissue section in situ hybridization (ISH) analysis with rag-1 probe reveals that cortex-medullary regionalization has begun between 1 and 2 wpf as rag-1 expression clearly demarcated the cortex, whereas the medulla was rag-1 negative. The presence of TCRAC-positive cells in the medulla by 2-3 wpf, suggests that the thymic selection processes had begun. The zebrafish thymus is morphologically mature by 3 wpf. Early signs of thymic involution were observed in zebrafish aged 15 wpf.

Probable aerosol transmission of severe fever with thrombocytopenia syndrome virus in southeastern China

Some clusters of severe fever with thrombocytopenia syndrome virus (SFTSV) infection were reported in China as of 2010. However, to date, there has been no epidemiologic evidence of aerosol transmission of SFTSV. Epidemiologic investigations were conducted after a cluster of 13 cases of SFTSV in May 2014. A total of 13 cases, including 11 confirmed cases and one clinically diagnosed case, were identified besides the case of the index patient. The index patient experienced onset of SFTSV on 23 April and died on 1 May. The patients with secondary cases had onset from 10 to 16 May, peaking on 13 May. Moreover, eight secondary cases occurred in family members of the index patient, and the other five cases occurred in neighbors of the index patient. According to epidemiologic investigations, patients 1, 3, 4, 5, 6, 7, 9 and 12 contracted the disease through contact with blood of the index patient. Notably, patients 8 and 10 did not have a history of contact with the blood of the index patient, but they stayed in the mourning hall for hours. SFTSV could be transmitted from person to person by direct contact and/or aerosol transmission, and it is important to consider aerosol transmission as a possible transmission route.