The crystalline polymorphism of mannan in plant cell walls and after recrystallisation

Mannan-rich plant cell walls were mechanically disintegrated and chemically extracted in order to ascertain their morphology and structure by electron microscopy and electron diffraction. For Acetabularia crenulata and Codium fragile, the cell-wall fragments were found to consist of alkali-resistant fibrillar mannan II encrusted with alkali-soluble granular mannan I. In the case of ivory nuts (Phytelephas macrocarpa) there is, in addition, a microfibrillar cellulose component which was also identified. The mannan I—mannan II polymorphism was also obtained when various mannan fractions were recrystallized from solution. In these recrystallizations, the occurrence of one or the other polymorph was found to depend on several parameters: the molecular weight of the mannan, the temperature of crystallization and the polarity of the crystallization medium.Abbreviations DP degree of polymerization - EDTA ethylenediaminetetraacetic acid Affiliated with the Scientific and Medical University of Grenoble     

Endogenous C-terminal fragments of beta-amyloid precursor protein from Xenopus laevis skin exudate

Using a monoclonal antibody against the entire C-terminal end of human APP₆₉₅ (643–695 sequence) and a monoclonal antibody directed against human β[1–40] amyloid peptide (βA), we show the existence of endogenous peptides proteolytically derived from APP in skin exudate of the non transgenic Xenopus laevis frog. The majority of the immunoreactivity is found associated with a 30 kDa molecular species. Biochemical fractionation followed by mass spectrometry identification allowed us to assign this molecular species to C-terminal APP fragments containing all or part of βA. According to the nature of N- and C-terminal amino acids we identified endogenous β-, γ-, ε-secretase-like activities, caspase-like activity and numerous endogenous cleavage sites within the β-amyloid sequence at same sites as those observed in human βA sequence. All these homologies with human indicate that X. laevis skin exudate is a good natural model to study βA metabolism. In this way, interestingly, we identified endogenous cleavages at prohormone convertase-like sites not yet described at the same sites in human. Finally, all identified peptide fragments were stably associated with a 20.2 kDa protein. These new observed features suggest new research pathways concerning human βA metabolism and carriage of hydrophobic peptide fragments issued from APP processing.     

Sequence Comparison of Plant Ornithine Decarboxylases Reveals High Homology and Lack of Introns

We have designed and constructed four oligonucleotides corresponding to the most conserved regions of ornithine decarboxylases (ODC; EC 4.1.1.17) of plant origin. These oligonucleotides were used for the amplification of homologous fragments from several plants (Zea mays, Capsicum annuum, Sorghum bicolor, Phaseolus vulgaris, Carica papaya and Daucus carota). The amplified fragments were cloned and sequenced, revealing high homology to other ODCs. Peptide sequences coded by these fragments were compared by Clustal analyses. These analyses identified the location of the conserved sequences corresponding to the binding sites of substrate and cofactor. Data demonstrated that the plant ODCs fragments lacked intron sequences and were extremely homologous (over 80 %), constituting a compact group separated from other eukaryotic ODCs. This revised version was published online in July 2006 with corrections to the Cover Date.     

Foreign exploration for Scirtothrips perseae Nakahara (Thysanoptera: Thripidae) and associated natural enemies on avocado (Persea americana Miller)

Scirtothrips perseae Nakahara was discovered attacking avocados in California, USA, in 1996. Host plant surveys in California indicated that S. perseae has a highly restricted host range with larvae being found only on avocados, while adults were collected from 11 different plant species. As part of a management program for this pest, a “classical” biological control program was initiated and foreign exploration was conducted to delineate the home range of S. perseae, to survey for associated natural enemies and inventory other species of phytophagous thrips on avocados grown in Mexico, Guatemala, Costa Rica, the Dominican Republic, Trinidad, and Brazil. Foreign exploration efforts indicate that S. perseae occurs on avocados grown at high altitudes (>1500 m) from Uruapan in Mexico south to areas around Guatemala City in Guatemala. In Costa Rica, S. perseae is replaced by an undescribed congener as the dominant phytophagous thrips on avocados grown at high altitudes (>1300 m). No species of Scirtothrips were found on avocados in the Dominican Republic, Trinidad, or Brazil. In total, 2136 phytophagous thrips were collected and identified, representing over 47 identified species from at least 19 genera. The significance of these species records is discussed. Of collected material 4% were potential thrips biological control agents. Natural enemies were dominated by six genera of predatory thrips (Aeolothrips, Aleurodothrips, Franklinothrips, Leptothrips, Scolothrips, and Karnyothrips). One genus each of parasitoid (Ceranisus) and predatory mite (Balaustium) were found. Based on the results of our sampling techniques, prospects for the importation of thrips natural enemies for use in a “classical” biological control program in California against S. perseae are not promising.     

Diversity and structure of shrew communities in montane forests of southeast Kenya

As a step towards setting conservation priorities for declining moist forests in southeast Kenya, we assessed for small mammal diversity and distribution. These habitats are under severe pressure due to increased demand an forests products and arable land, yet there is a dearth of information an impacts an biodiversity. Over an eight-month period, we used a combination of box and pitfall traps with drift fences to study 13 forest fragments in five geographic areas ranging between 3°28′−4°10′ S and 38°28′−39°2b′ E. We recorded 12 species including 10 soricids and two macroscelids in 31440 trap nights. Diversity estimates using rarefaction method indicate a species richness of 12, consistent with our collection. There were six unique species, each limited in distribution to one forest fragment. Our record of Crocidura cf. selina in Kyulu Hills is the first outside Mabira forest in Uganda where it is considered endemic and endangered. We also report the first record of C. fuscomurina in Kenya, white those of C. Luna and Suncus megalura are first in the southeast of the country. By providing new ranges to four species, our study is of significance to the biogeography and conservation of forest small mammals in the region.     

Clone bank and physical and genetic map of potato chloroplast DNA

Summary Clone banks of PvuII, BamHI and XhoI fragments were generated of the Solanum tuberosum cv Katahdin plastome. These clone banks, in conjunction with molecular hybridization to tobacco ctDNA probes, were used to construct a physical map of potato ctDNA. The potato plastome was found to be a circular molecule of 155–156 Kbp containing two inverted repeat regions of 23–27 Kbp. The arrangement of restriction sites is very similar to that of other Solanaceae plastomes. Heterologous hybridization to known ctDNA encoded gene probes from tobacco allowed us to establish a genetic map of the potato chloroplast genome. The arrangement of these genes on the potato plastome resembles that on most higher plant ctDNAs.     

Mitochondrial genome diversity among cultivars of daucus carota (ssp. sativus) and their wild relatives

Summary Restriction fragment patterns of mitochondrial DNAs (mtDNAs) from 13 carrot cultivars (Daucus carota ssp. sativus), wild carrot (ssp. carota), ssp. gummifer, and D. capillifolius were compared with each other using four restriction endonucleases. The mtDNAs of the 13 carrot cultivars could be classified into three distinct types — I, II and III — and were also clearly distinguishable from the mtDNAs of wild carrot (type IV), gummifer (V) and D. capillifolius (VI). The proportions of common restriction fragments (F values) shared by two of the three mtDNA types (I, II and III) of carrot cultivars were approximately 0.5–0.6. The F values were 0.4–0.5 for mitochondrial genomes between wild carrot, ssp. gummifer and D. capillifolius. The mitochondrial genomes between wild carrot and the carrot cultivars showed closer homologies those between wild carrot, ssp. gummifer, and D. capillifolius. The diversity of the mitochondrial genomes among the carrot cultivars is too high to presume that it was generated from the cytoplasm of only one common ancestor during the relatively short history of carrot breeding. These results suggested that the three types of cytoplasms found in the carrot cultivars might have existed in a prototype of D. carota in pre-historical times.     

Dissection of a pollen-specific promoter from maize by transient transformation assays

We have previously reported the isolation and characterization of a gene (Zm 13) from Zea mays which shows a pollen-specific pattern of expression. Stably transformed tobacco plants containing a reporter gene linked to portions of the Zm 13 5 flanking region show correct temporal and spatial expression of the gene. Here we present a more detailed analysis of the 5 regions responsible for expression in pollen by utilizing a transient expression system. Constructs containing the -glucuronidase (GUS) gene under the control of various sized fragments of the Zm13 5 flanking region were introduced into Tradescantia and Zea mays pollen via high-velocity microprojectile bombardment, and monitored both visually and with a fluorescence assay. The results suggest that sequences necessary for expression in pollen are present in a region from –100 to –54, while other sequences which amplify that expression reside between –260 and –100. The replacement of the normal terminator with a portion of the Zm13 3 region containing the putative polyadenylation signal and site also increased GUS expression. While the –260 to –100 region contains sequences similar to other protein-binding domains reported for plants, the –100 to –54 region appears to contain no significant homology to other known promoter fragments which direct pollen-specific expression. The microprojectile bombardment of Tradescantia pollen appears to be a good test system for assaying maize and possibly other monocot promoter constructs for pollen expression.     

Hemocyte differentiation in the hematopoietic organs of the silkworm, <Emphasis Type="Italic">Bombyx mori</Emphasis>: prohemocytes have the function of phagocytosis

Hemocytes isolated from the larval hematopoietic organs of the silkworm were classified following staining with acridine orange and propidium iodide. Among the hemocytes isolated from the hematopoietic organs of whole fifth larval and wandering stages, most were prohemocytes (60%–70%) and oenocytoids (30%–40%). Granulocytes comprised only about 0.5%–1% at the wandering stage and were even rarer at other stages; no spherulocytes or plasmatocytes were found. Therefore, hemocyte differentiation inside larval hematopoietic organs is not as extensive as previously thought. Following 10–30 min in vitro culture of hemocytes isolated from larval hematopoietic organs, many young granulocytes and plasmatocytes appeared. Furthermore, during phagocytosis assays, prohemocytes were seen to adopt the morphology of plasmatocytes, containing fragments of phagocytosed cells. Our results underline the similarities between Drosophila and Bombyx hematopoiesis.     

Comparison of habitat quality and diet of Colobus vellerosus in forest fragments in Ghana

The forest fragments surrounding the Boabeng-Fiema Monkey Sanctuary (BFMS) in central Ghana shelter small populations of Colobus vellerosus. Little is known about these populations or the ability of the fragments to support them, despite the fact that these fragments represent potentially important habitat for the colobus in this region. We compared the diet of three groups of C. vellerosus in the fragments to two groups in BFMS. We also examined the differences in plant species composition and food abundance among fragments. The study took place from June to November 2003. Dietary data were collected using scan sampling. Plant species composition and food abundance were evaluated using tree plots and large tree surveys. As in BFMS groups, leaves constituted the highest proportion of the diet of fragment groups, yet the colobus in fragments fed on more lianas than did those in BFMS. Over 50% of all species observed eaten by colobus in the fragments were not consumed in BFMS groups during the same season. Food abundance was similar between fragments and BFMS, although species composition differed. There was no relationship between the density of colobus and the density of food trees or percentage of food species, suggesting that other factors may be influencing the number of colobus present. This study highlights the broad dietary range of C. vellerosus, which may be a factor allowing its survival in these fragments.     

Intergeneric hybridization between Pleurotus ostreatus and Schizophyllum commune by PEG-induced protoplast fusion

Intergeneric hybridization between Pleurotus ostreatus and Schizophyllum commune was studied using PEG-induced fusion. The fusion of protoplasts from auxotrophic mutant strains resulted in the formation of fusion hybrids in the frequencies of 3.6 to 7.3×10^–5. Most of these fusion hybrids were monokaryotic and sterile and no heterokaryosis occurred. Most fusants showed a significantly higher nuclear DNA content when compared to parental strains and no diploids (parent 1 genome plus parent 2 genome) were found. Some fusion hybrids revealed both parental fragments in nuclear and mitochondrial rDNA PCR profiles. AP-PCR (Arbitrarily-primed Polymerase Chain Reaction) fingerprints also indicated that most of the fusion products were recombinant hybrids.     

Spatial variation in the strength of mutualism between a jumping spider and a terrestrial bromeliad: Evidence from the stable isotope N

Psecas chapoda, a neotropical jumping spider strictly associated with the terrestrial bromeliad Bromelia balansae in cerrados and semi-deciduous forests in South America, effectively contributes to plant nutrition and growth. In this study, our goal was to investigate if spider density caused spatial variations in the strength of this spider–plant mutualism. We found a positive significant relationship between spider density and δ¹⁵N values for bromeliad leaves in different forest fragments. Open grassland Bromeliads were associated with spiders and had higher δ¹⁵N values compared to forest bromeliads. Although forest bromeliads had no association with spiders their total N concentrations were higher. These results suggest that bromeliad nutrition is likely more litter-based in forests and more spider-based in open grasslands. This study is one of the few to show nutrient provisioning and conditionality in a spider–plant system.     

Chromosomes in somatic hybrids between Nicotiana plumbaginifolia and a monoploid potato

Summary Leaf mesophyll protoplasts of the monohaploid potato (Solanum tuberosum L.) clone H7322 were fused with callus protoplasts of nitrate reductase deficient (NR^–) mutants Cnx 20 and NA 36 of Nicotiana plumbaginifolia. Somatic hybrid lines were selected for nitrate reductase proficiency. All callus lines tested appeared to be stable for the retention of the potato chromosome carrying the compensating NR gene when grown for over 1.5 years in the absence of nitrate. Shoots were regenerated from six different fusion lines of Cnx 20 + H7322 24 months after fusion. Chromosomal analysis in callus cultures revealed that in both fusion combinations 40–120 N. plumbaginifolia chromosomes were present, as were 9–20 potato chromosomes. Cells with 17 potato chromosomes in combination with a relatively small number (31) of N. plumbaginifolia chromosomes were found in one line. Preferential loss of species-specific chromosomes was not observed. Analysis of regenerating tissue from three lines of Cnx 20 + H7322 revealed that after 24 months of culture intra- and intergeneric translocations, fragments and deletions were present. Elimination of the potato and N. plumbaginifolia chromosomes had taken place before and after genome doubling.     

Cultivation and carrageenan yield and quality ofKappaphycus alvarezii in the waters of Vietnam

The carrageenan-producing red algaKappaphycus alvarezii (Doty) Doty was brought to Vietnam from Japan in 1993. Branch fragments of this species were cultivated in a pond, lagoon, inlet and offshore in Vietnam for the first time. The best daily growth rate (DGR) of plants grown in the lagoon area attained 9–11 % day^–1 in May to June (cold season). The water temperature and salinity in this area ranged from 27.2–32.4 °C and 31.4–33.7 °C, respectively. DGR of plants grown in the inlet ranged from 7 to 9% day^–1 in June. Grazing by fish has been observed to occur in this area. The DGR of plants grown in the pond ranged from 5–6% in January–July, but decreased to less than 4% day^–1 in August (hot season). K. alvarezii in Vietnam showed a carrageenan yield of 18.8–24.6% and gel strength of 1566–1712 g cm^–2. These values are similar ones obtained fromK. alvarezii cultivated in the Philippines and Indonesia.     

Net nitrogen mineralization in soils under six indigenous tree species,an abandoned pasture and a secondary forest in the atlantic lowlands of costa rica

Nitrogen mineralization, nitrification potentials, pH, total N, C, extractable P and cations were measured in soils under 4-year-old, mono-specific stands of six fast-growing, native tree species, an abandoned pasture, and a 20-year-old secondary forest, as part of a study on the use of indigenous tree species for rehabilitation of soil fertility on degraded pastures at the La Selva Biological Station in the Atlantic humid lowlands of Costa Rica. Soil net nitrification potential rates were higher under two N-fixing, leguminous species,Stryphnodendron microstachyum Poepp. et Endl. (1.1–1.9 mg kg^–1 day^–1) andDalbergia tucurensis Donn. Smith (0.7–1.5 mg kg^–1 day^–1), than under the non-N-fixing trees in the plantation,Vochysia guatemalesis Don. Sm.,Vochysia ferruginea Mart,Dipteryx panamensis (Pittier) Record and Mell andHyeronima alchorneoides Fr. Allemao (0.2–0.8 mg kg^–1 day^–1). Values under the N-fixing trees were comparable to those found in secondary forest. There were no statistically significant differences in soil total N or in other nurtients between the species. Results of pH measurements done before and after incubation did not show any clear evidence of a pH drop attributable to nitrification.     

Hox genes in the echiuroid Urechis unicinctus

An echiuroid species, Urechis unicinctus, was surveyed for Hox genes using polymerase chain reaction with homeobox-specific degenerate primers. We identified nine distinct homeodomain-containing gene fragments. These nine fragments were classified by comparative analysis. This analysis revealed that this echiuroid possessed at least three Hox genes from the anterior group, five from the central group, and one from the posterior group.Sung-Jin and Dae-Hee Lee contributed equally to this work.An erratum to this article can be found at     

Genomic Cloning and Characterization of a Novel Lectin Gene from <Emphasis Type="Italic">Zantedeschia aethiopica</Emphasis>

A new lectin gene was isolated by using genomic walker technology and revealed to encode a mannose-binding lectin. Analysis of a 2233 bp segment revealed a gene including a 1169 bp 5′ flanking region, a 417 bp open reading frame (ORF) and a 649 bp 3′ flanking region. There are two putative TATA boxes and eight possible CAAT boxes lie in the 5′ flanking region. The ORF encodes a 15.1 kDa precursor, which contains a 24-amino acid signal peptide. One possible polyadenylation signal is found in the 3′-flanking region. No intron was detected within the region of genomic sequence corresponding to zaa (Zantedeschia aethiopica agglutinin) full-length cDNA, which is typical of other mannose-binding lectin gene that have been reported. The deduced amino acid sequence of the lectin gene coding region shares 49–54% homology with other known lectins. The cloning of this new lectin gene will allow us to further study its structure, expression and regulation mechanisms.     

Cloning of soybean genes induced during hypersensitive cell death caused by syringolide elicitor

Syringolide elicitors produced by bacteria expressing Pseudomonas syringae pv. glycinea avirulence gene D (avrD) induce hypersensitive cell death (HCD) only in soybean (Glycine max [L.] Merr.) plants carrying the Rpg4 disease resistance gene. Employing a differential display method, we isolated 13 gene fragments induced in cultured cells of a soybean cultivar Harosoy (Rpg4) treated with syringolides. Several genes for isolated fragments were induced by syringolides in an rpg4 cultivar Acme as well as in Harosoy; however, the genes for seven fragments designated as SIH (for syringolide-induced/HCD associated) were induced exclusively or strongly in Harosoy. cDNA clones for SIH genes were obtained from a cDNA library of Harosoy treated with syringolide. Several sequences are homologous to proteins associated with plant defense responses. The SIH genes did not respond to a non-specific -glucan elicitor, which induces phytoalexin accumulation but not HCD, suggesting that the induction of the SIH genes is specific for the syringolide–Harosoy interaction. HCD and the induction of SIH genes by syringolides were independent of H₂O₂. On the other hand, Ca²⁺ was required for HCD and the induction of some SIH genes. These results suggest that the induction of SIH genes by syringolides could be activated through the syringolide-specific signaling pathway and the SIH gene products may play an important role(s) in the processes of HCD induced by syringolides.Abbreviations AOS active oxygen species - CHS chalcone synthase - DPI diphenylene iodonium - HCD hypersensitive cell death - HR hypersensitive response - PAL phenylalanine ammonia lyase - SID syringolide-induced/defense associated - SIG syringolide-induced/general - SIH for syringolide-induced/HCD associated - XET xyloglucan endotransglycosylase     

Seven Hox gene sequences from the asterinid starfish Patiriella exigua (Echinodermata: Asteroidea)

Partial homeobox gene fragments were amplified from Patiriella exigua genomic DNA by PCR using degenerate primers. The primers spanned a region of 82 nucleotides within the homeobox, encompassing amino acids 21–47 of the homeodomain. The deduced amino acid sequences of the seven Hox gene sequences plus one Xlox-type gene sequence from P. exigua are presented and compared with similar sequences from other organisms. This work is a preliminary step in the analysis of the evolution of development in the Patiriella species group and the roles of Hox gene expression therein.