Effects of daylength,irradiance and settlement density on the growth and reproduction of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> gametophytes

The effects of daylength, irradiance and spore settlement density on the growth, maturation and sporophyte production of Undaria pinnatifida (Harvey) Suringar gametophytes were examined using a factorial experimental design in culture. The growth of Undaria gametophytes increased with increasing daylength (8, 12 and 16 h), but the maximum fertility occurred at a daylength of 12 h followed by 8 and 16 h. Gametophytes grew better at the 16 h daylength under the same mean daily irradiance (MDI) of 20 μmol photons m⁻² s⁻¹. However, the fertility was higher at the short daylength (8 h), indicating that the maturation of U. pinnatifida gametophytes is influenced by daylength rather than by the MDI. Vegetative growth and sporophyte production of gametophytes were better at 60 μmol photons m⁻² s⁻¹ than at 30 μmol photons m⁻² s⁻¹ under a 8:16 h LD (Light: Dark) cycle, and their growth and maturation were density-dependant in 16 and 12 h daylength, respectively. These results suggest that the U. pinnatifida gametophytes require a certain amount of light for the growth and reproduction, and intraspecific competition occurred under the optimal growth and maturation conditions. However, the sporophyte recruits per unit has been enhanced with increasing spore settlement density at 8 and 12 h daylengths indicating that high settlement density gives a benefit for maintaining population, even though the sporophyte production of each female plant is inhibited. In conclusion, the vegetative growth, reproduction and sporophyte production of U. pinnatifida gametophytes are retarded at a low irradiance above growth saturation and a high settlement density, and are determined by daylength.     

Growth and reproductive patterns of <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> sporophytes in a cultivation farm in Busan,Korea

Monthly growth and reproduction of Undaria pinnatifida sporophytes were examined over a period of 5 months in a cultivation farm in Korea. A total of 11 characters of Undaria were measured to determine a reliable morphological character representing its growth and reproduction. Plant weight of Undaria sporophytes increased steadily over the experimental period, but it increased in four different ways. Undaria pinnatifida increased body weight by growth in length and width (October–early December), and by growth in width with the thickening of blade and stipe when sporophytes began to be fertile (December–January). In the middle of January, growth in length and width had almost stopped with the maturation of Undaria sporophytes. Finally, the weight of Undaria increased again by growth in width at the end of February. Present results indicate that Undaria sporophytes increase body weight by growth in length and width at different times, and the relationship between reproduction and vegetative growth is exclusive. Plant weight was positively correlated and fitted well with stipe width and blade width. The blade of Undaria was very thin (ca. 254 μm) and breakable by wave action, but its stipe was strong and relatively thick (ca. 8.7 mm). Furthermore, the fertility of U. pinnatifida was fitted better with stipe width than blade width. Thus, we suggest that the stipe width is the most feasible character with which to estimate the growth and reproduction of U. pinnatifida sporophytes in the cultivation farm.     

Effect of light period on egg-discharge of gametophyte clones of <Emphasis Type="BoldItalic">Undaria pinnatifida</Emphasis> (Phaeophyta)

A sporeling culture method using gametophyte clones developed in the early 1990s led to egg discharge occurring in the dark 5 min after the start of the dark period under growth under a 11:13 L-D photoperiod. The course of egg discharge could be disturbed by light, with irradiance as low as 5–6 μmol photon m⁻² s⁻¹ causing 75–80% of the discharged eggs to detach from the oogonia and consequently to die within several hours. In order to enhance outgrowth rate of young sporophytes, a study was conducted to test the effect of controlling darkness in the period 2–3 h after dusk. When the slides were transferred from the standard 11:13 L-D regime to continuous light, eggs were discharged 5 min after the end of the light phase and peaked 5–l5 min later on first day after transfer, indicating that the female gametes “remember” the light-dark regime. This suggests the existence of an endogenous circadian rhythm. During the second and third days, very few eggs were discharged throughout the 11 h of the normal light phase of the L-D regime, indicating the inhibitory effect of continuous light and that the rhtyhm is easily damped by light.     

<Emphasis Type="Italic">Undaria pinnatifida</Emphasis> fucoidan extract protects against CCl<Subscript>4</Subscript>-induced oxidative stress

This study was performed to elucidate the effects of Undaria pinnatifida fucoidan extract (UPFE) in preventing CCl₄-induced oxidative stress. UPFE (100 mg/kg) was intraperitoneally administered to rats for 14 days. On day 15, CCl₄ dissolved in olive oil (50% CCl₄) was injected 12 h before they were anesthetized and dissected. To measure UPFE-mediated antioxidation, we examined the levels of glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH) in serum, as well as malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx) in liver homogenates. CCl₄ treatment markedly increased the levels of GOT, GPT, ALP, LDH, and MDA and significantly decreased levels of SOD, CAT, and GPx. UPFE pretreatment decreased levels of GOT, GPT, ALP, LDH, and MDA, by 62.8, 68.5, 41.9, 72.7, and 122%, respectively and increased those of SOD, CAT, and GPx by 111.1, 15.9, and 52.6%, respectively. These results showed that UPFE has antioxidant effects against CCl₄-induced oxidative stress.     

The occurrence of pinhole disease in relation to developmental stage in cultivated <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> (Harvey) Suringar (Phaeophyta) in Korea

Infection rates of pinhole disease in farmed Undaria pinnatifida (Harvey) Suringar were examined between November 2002 and April 2003 at an Undaria farm at Wando on the southwestern coast of Korea. The growth stages of U. pinnatifida can be defined as: a growth phase from December to the end of February, and a decay phase from March to April. There was a significant increase in the level of infection with pinhole disease (measured as the number of pinholes per cm²) between December and April (P < 0.01). Infection progressed from the upper part of the frond in December to the basal part in April. The infection rate of pinhole disease in relation to growth phase on farms over time is limited by the harvest of the seaweed crop at the end of the cultivation period in April. The midrib, sporophyll and stipe showed no signs of infection at any time during the cultivation period. The reduced physiological activity and tissue aging that occurred over time in the sporophytic life phase is the probable cause of the increasing infection rate of the disease.     

The <Emphasis Type="Italic">Caenorhabditis</Emphasis><Emphasis Type="Italic">briggsae</Emphasis> genome contains active <Emphasis Type="Italic">CbmaT1</Emphasis> and <Emphasis Type="Italic">Tcb1</Emphasis> transposons

The maT clade of transposons is a group of transposable elements intermediate in sequence and predicted protein structure to mariner and Tc transposons, with a distribution thus far limited to a few invertebrate species. We present evidence, based on searches of publicly available databases, that the nematode Caenorhabditis briggsae has several maT-like transposons, which we have designated as CbmaT elements, dispersed throughout its genome. We also describe two additional transposon sequences that probably share their evolutionary history with the CbmaT transposons. One resembles a fold back variant of a CbmaT element, with long (380-bp) inverted terminal repeats (ITRs) that show a high degree (71%) of identity to CbmaT1. The other, which shares only the 26-bp ITR sequences with one of the CbmaT variants, is present in eight nearly identical copies, but does not have a transposase gene and may therefore be cross mobilised by a CbmaT transposase. Using PCR-based mobility assays, we show that CbmaT1 transposons are capable of excising from the C. briggsae genome. CbmaT1 excised approximately 500 times less frequently than Tcb1 in the reference strain AF16, but both CbmaT1 and Tcb1 excised at extremely high frequencies in the HK105 strain. The HK105 strain also exhibited a high frequency of spontaneous induction of unc-22 mutants, suggesting that it may be a mutator strain of C. briggsae.     

In planta transformation of <Emphasis Type="Italic">Notocactus scopa</Emphasis> cv. <Emphasis Type="Italic">Soonjung</Emphasis> by <Emphasis Type="Italic">Agrobacterium </Emphasis><Emphasis Type="Italic">tumefaciens</Emphasis>

Notocactus scopa cv. Soonjung was subjected to in planta Agrobacterium tumefaciens-mediated transformation with vacuum infiltration, pin-pricking, and a combination of the two methods. The pin-pricking combined with vacuum infiltration (20-30 cmHg for 15 min) resulted in a transformation efficiency of 67-100%, and the expression of the uidA and nptII genes was detected in transformed cactus. The established in planta transformation technique generated a transgenic cactus with higher transformation efficiency, shortened selection process, and stable gene expression via asexual reproduction. All of the results showed that the in planta transformation method utilized in the current study provided an efficient and time-saving procedure for the delivery of genes into the cactus genome, and that this technique can be applied to other asexually reproducing succulent plant species.     

<Emphasis Type="Italic">Drosophila</Emphasis><Emphasis Type="Italic">P</Emphasis> transposons of the urochordata <Emphasis Type="Italic">Ciona intestinalis</Emphasis>

P transposons belong to the eukaryotic DNA transposons, which are transposed by a cut and paste mechanism using a P-element-coded transposase. They have been detected in Drosophila, and reside as single copies and stable homologous sequences in many vertebrate species. We present the P elements Pcin1, Pcin2 and Pcin3 from Ciona intestinalis, a species of the most primitive chordates, and compare them with those from Ciona savignyi. They showed typical DNA transposon structures, namely terminal inverted repeats and target site duplications. The coding region of Pcin1 consisted of 13 small exons that could be translated into a P-transposon-homologous protein. C. intestinalis and C. savignyi displayed nearly the same phenotype. However, their P elements were highly divergent and the assumed P transposase from C. intestinalis was more closely related to the transposase from Drosophila melanogaster than to the transposase of C. savignyi. The present study showed that P elements with typical features of transposable DNA elements may be found already at the base of the chordate lineage. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Floral development and systematic position of <Emphasis Type="Italic">Arillastrum</Emphasis>, <Emphasis Type="Italic">Allosyncarpia</Emphasis>, <Emphasis Type="Italic">Stockwellia</Emphasis> and <Emphasis Type="Italic">Eucalyptopsis</Emphasis> (Myrtaceae)

We have investigated the floral ontogeny of Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis (of the eucalypt group, Myrtaceae) using scanning electron microscopy and light microscopy. Several critical characters for establishing relationships between these genera and to the eucalypts have been determined. The absence of compound petaline primordia in Arillastrum, Allosyncarpia, Stockwellia and Eucalyptopsis excludes these taxa from the eucalypt clade. Post-anthesis circumscissile abscission of the hypanthium above the ovary in Stockwellia, Eucalyptopsis and Allosyncarpia is evidence that these three taxa form a monophyletic group; undifferentiated perianth parts and elongated fusiform buds are characters that unite Stockwellia and Eucalyptopsis as sister taxa. No floral characters clearly associate Arillastrum with either the eucalypt clade or the clade of Stockwellia, Eucalyptopsis and Allosyncarpia.We gratefully acknowledge Clyde Dunlop and Bob Harwood (Northern Territory Herbarium) for collecting specimens of Allosyncarpia, and Bruce Gray (Atherton) for collecting specimens of Stockwellia. The Australian National Herbarium (CANB) kindly lent herbarium specimens of Eucalyptopsis for examination. This research was supported by a University of Melbourne Research Development Grant to Andrew Drinnan.     

Extraction of fucoxanthin and polyphenol from <Emphasis Type="Italic">Undaria pinnatifida</Emphasis> using supercritical carbon dioxide with co-solvent

Extraction of brown seaweed (Undaria pinnatifida) oil was carried out by using supercritical carbon dioxide (SCO₂) and ethanol as co-solvent. The flow rate of ethanol was 3.0% (v/v) as compared to that of SCO₂. Experiments were performed in a semi-batch flow apparatus on dried samples at temperatures from 303 to 333 K and pressures from 80 to 300 bar. Fucoxanthin and polyphenol were quantitatively analyzed by using HPLC and UV-spectrometer. The highest yields of fucoxanthin and polyphenol were shown at 200 bar, 323 K and 250 bar, 333 K, respectively. The solubility of fucoxanthin in SCO₂ agreed well with the Chrastil model.     

Phylogenetic analyses of <Emphasis Type="Italic">Uromyces viciae-fabae</Emphasis> and its varieties on <Emphasis Type="Italic">Vicia</Emphasis>, <Emphasis Type="Italic">Lathyrus</Emphasis>, and <Emphasis Type="Italic">Pisum</Emphasis> in Japan

A pea rust fungus, Uromyces viciae-fabae, has been classified into two varieties, var. viciae-fabae and var. orobi, based on differences in urediniospore wall thickness and putative host specificity in Japan. In principal component analyses, morphological features of urediniospores and teliospores of 94 rust specimens from Vicia, Lathyrus, and Pisum did not show definite host-specific morphological groups. In molecular analyses, 23 Uromyces specimens from Vicia, Lathyrus, and Pisum formed a single genetic clade based on D1/D2 and ITS regions. Four isolates of U. viciae-fabae from V. cracca and V. unijuga could infect and sporulate on P. sativum. These results suggest that U. viciae-fabae populations on different host plants are not biologically differentiated into groups that can be recognized as varieties.Contribution no. 184, Laboratory of Plant Parasitic Mycology, Institute of Agriculture and Forestry, University of Tsukuba, Japan     

Regulation of stipule development by <Emphasis Type="Italic">COCHLEATA</Emphasis> and <Emphasis Type="Italic">STIPULE</Emphasis>-<Emphasis Type="Italic">REDUCED</Emphasis> genes in pea <Emphasis Type="Italic">Pisum sativum</Emphasis>

Pisum sativum L., the garden pea crop plant, is serving as the unique model for genetic analyses of morphogenetic development of stipule, the lateral organ formed on either side of the junction of leafblade petiole and stem at nodes. The stipule reduced (st) and cochleata (coch) stipule mutations and afila (af), tendril-less (tl), multifoliate-pinna (mfp) and unifoliata-tendrilled acacia (uni-tac) leafblade mutations were variously combined and the recombinant genotypes were quantitatively phenotyped for stipule morphology at both vegetative and reproductive nodes. The observations suggest a role of master regulator to COCH in stipule development. COCH is essential for initiation, growth and development of stipule, represses the UNI-TAC, AF, TL and MFP led leafblade-like morphogenetic pathway for compound stipule and together with ST mediates the developmental pathway for peltate-shaped simple wild-type stipule. It is also shown that stipule is an autonomous lateral organ, like a leafblade and secondary inflorescence.     

Study of tauopathies by comparing <Emphasis Type="Italic">Drosophila</Emphasis> and human <Emphasis Type="Italic">tau</Emphasis> in <Emphasis Type="Italic">Drosophila</Emphasis>

The microtubule-binding protein tau has been investigated for its contribution to various neurodegenerative disorders. However, the findings from transgenic studies, using the same tau transgene, vary widely among different laboratories. Here, we have investigated the potential mechanisms underlying tauopathies by comparing Drosophila (d-tau) and human (h-tau) tau in a Drosophila model. Overexpression of a single copy of either tau isoform in the retina results in a similar rough eye phenotype. However, co-expression of Par-1 with d-tau leads to lethality, whereas co-expression of Par-1 with h-tau has little effect on the rough eye phenotype. We have found analogous results by comparing larval proteomes. Through genetic screening and proteomic analysis, we have identified some important potential modifiers and tau-associated proteins. These results suggest that the two tau genes differ significantly. This comparison between species-specific isoforms may help to clarify whether the homologous tau genes are conserved. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. This study was supported by the National Science Foundation of China (30270341; 30630028), the Multidisciplinary Program (Brain and Mind) of the Chinese Academy of Sciences, the Major State Basic Research Program (“973 program”; G2000077800; G2006CB806600; 2006CB911003), the Precedent Project of Important Intersectional Disciplines in the Knowledge Innovation Engineering of the Chinese Academy of Sciences (KJCX1-09-03).     

Synergistic interaction between sublethal doses of <Emphasis Type="Italic">Bacillus thuringiensis</Emphasis> and <Emphasis Type="Italic">Campoletis chlorideae</Emphasis> in managing <Emphasis Type="Italic">Helicoverpa armigera</Emphasis>

Campoletis chlorideae Uchida (Hymenoptera: Ichneumonidae) is an important solitary larval endoparasitoid of the tomato fruit borer Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae) in India. The interaction between Bacillus thuringiensis subspecies kurstaki (Btk) HD-1 and C. chlorideae was studied under laboratory condition to explore their compatibility in managing H. armigera. The results had indicated that the growth and development of H. armigera was affected in a dose-dependent manner upon feeding on sublethal doses of Btk HD-1-treated diets. There were no larval survivors in lethal doses of Btk HD-1 (LC₇₀ and LC₉₀). The growth and survival of the parasitoid were normal when the host larvae were fed with sublethal doses or subjected to short time exposure to lethal doses of Btk HD-1. However, the parasitoid offsprings developed slowly and pupal as well as adult period, adult weight and adult emergence rate were reduced significantly if the parasitoid was developing inside a severely Bt intoxicated host larvae. There were no evident differences in longevity of parasitoid adults that were fed on honey solution containing different concentrations of Btk HD-1 as compared to adults fed only on honey solution. This indicates no direct adverse effect of Btk HD-1 on C. chlorideae. Further, the gravid female parasitoid did not discriminate Btk HD-1 intoxicated and normal H. armigera larvae for oviposition. The result implies that spore crystal formulation of Btk HD-1 can be effectively used in a synergistic manner along with existing natural or prereleased population of C. chlorideae in organic farming or as components in biointensive IPM module for managing H. armigera.     

Phenotypic Switching of <Emphasis Type="Italic">Cryptococcus neoformans</Emphasis> and <Emphasis Type="Italic">Cryptococcus</Emphasis><Emphasis Type="Italic">gattii</Emphasis>

Microorganisms that live in fluctuating environments must constantly adapt their behavior to survive. The host constitutes an important microenvironment in opportunistic and primary fungal pathogens like Cryptococcus neoformans (C. neoformans) and Cryptococcus gattii (C. gattii). In clonal populations, adaptation may be achieved through the generation of diversity. For fungi phenotype switching constitutes a mechanism that allows them to change rapidly. Both C. neoformans and C. gattii undergo phenotypic switching, which allows them to be successful pathogens and cause persistent disease. Similar to other encapsulated microbes that exhibit phenotypic variation, phenotypic switching in Cryptococcus changes the polysaccharide capsule. Most importantly, in animal models phenotypic switching affects virulence and can change the outcome of infection. Virulence changes because C. neoformans and C. gattii switch variants elicit different inflammatory responses in the host. This altered host response can also affect the response to antifungal therapy and in some cases may even promote the selection of switch variants. This review highlights the similarity and differences between phenotypic switching in C. neoformans and C. gattii, the two dominant species that cause cryptococcosis in humans.     

Mutational analysis of the <Emphasis Type="Italic">gum</Emphasis> gene cluster required for xanthan biosynthesis in <Emphasis Type="Italic">Xanthomonas</Emphasis><Emphasis Type="Italic">oryzae</Emphasis> pv <Emphasis Type="Italic">oryzae</Emphasis>

Genome sequence analysis of Xanthomonas oryzae pv. oryzae has revealed a cluster of 12 ORFs that are closely related to the gum gene cluster of Xanthomonas campestris pv. campestris. The gum gene cluster of X. oryzae encodes proteins involved in xanthan production; however, there is little experimental evidence supporting this. In this study, biochemical analyses of xanthan produced by a defined set of X. oryzae gum mutant strains allowed us to preliminarily assign functions to most of the gum gene products: biosynthesis of the pentasaccharide repeating unit for GumD, GumM, GumH, GumK, and GumI, xanthan polymerization and transport for GumB, GumC, GumE, and GumJ, and modification of the pentasaccharide repeating unit for GumF, GumG, and GumL. In addition, we found that the exopolysaccharides are essential but not specific for the virulence of X. oryzae. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users. Sang-Yoon Kim and Jeong-Gu Kim contributed equally to this work.