Morphometric analysis of the genusHemerocallis L. (Liliaceae) in Korea

To better understand the patterns of variability and distributions ofHemerocallis in Korea, 53 locations were visited and measurements of 19 morphological and phenological characters were taken on plants directly from their natural habitats. For morphometric analysis, 10 plants from each of 34 populations and five herbarium specimens ofH. middendorffii were used and the data from 12 quantitative characters was analyzed using univariate analysis. Except the littoral populations of Cheju, Hong, Taehuksan, and Sohuksan Islands (H. hongdoensis M. Chung & S. Kang), three peninsular KoreanHemerocallis species can be recognized mainly in South Korea:H. hakuunensis Nakai (=H. micrantha Nakai, growing on southern, central, and northwestern Korea);H. thunbergii Baker (=H. coreana Nakai, found on southeastern and central Korea); andH. middendorffii Tr. et Mey. (central and northeastern Korea). Morphological and phenological features contributing to recognition of the three groups were; color of perianth, shape of roots, shape of inflorescence, flowering time, odor, length of inflorescence, width of the lowest bracts, length of perianth tube enclosing a ovary, width of the inner perianth lobes. Natural hybridization seems to be rare in KoreanHemerocallis. It appears that the KoreanHemerocallis species are relatively well characterized by their distribution patterns, phenology, and habitats compared with the JapaneseHemerocallis species.     

The structure and evolution of the human salivary proline-rich protein gene family

We present the nucleotide sequences of four members of the six-member human salivary prolinerich protein (PRP) gene family. The four genes are PRB1 and PRB2, which encode basic PRPs, and PRB3 and PRB4, which encode glycosylated PRPs. Each PRB gene is approximately 4.0 kb in length and contains four exons, the third of which is entirely composed of 63-bp tandem repeats and encodes the proline-rich portion of the protein products. Exon 3 contains different numbers of tandem repeats in the different PRB genes. Variation in the numbers of these repeats is also responsible for length variations in different alleles of the PRB genes. We have determined a probable evolutionary history of the human PRP gene family by comparing the nucleotide sequences of the six PRP genes. The present-day six PRP loci probably evolved from a single ancestral gene by four sequential gene duplications, leading to six genes that fall into three subsets, each consisting of two genes. During this evolutionary process, multiple rearrangements and gene conversion occurred mainly in the region from the 3 end of IVS2 and the 3 end of exon 3.     

Effect of nitrogen application on growth and photosynthetic nitrogen use efficiency in two ecotypes of wild strawberry, Fragaria chiloensis

The relationships between increasing nitrogen fertilization and growth, maximum CO₂ assimilation and the initial slope of the CO₂ response curve were studied in 2 ecotypes of wild strawberry, Fragaria chiloensis (L.) Duchn. Nitrogen accumulation of CA11, an ecotype from a low-nutrient dune site, was greater at all nitrogen concentrations than that of RCP37, an ecotype from a higher-nutrient strand site. Maximum CO₂ assimilation, total Rubisco activity, dry weight, and initiation of leaves and crowns were higher in CAI1 than RCP37 as nitrogen treatment was increased from 0 to 200 mg ^l-1, whereas these parameters were lower in CAl1 when fertilized at 300 mg T¹, but not in RCP37. The mean leaf area of CA11 was greater than RCP37 when grown with no supplemental nitrogen, but mean leaf area of the 2 lines was similar under nitrogen fertilization. Maximum CO₂ assimilation and carboxylation efficiency increased with increasing leaf nitrogen in both clones. At equivalent concentrations of leaf nitrogen, RCP37 had higher CO₂ assimilation and carboxylation efficiency than CA11 and the difference between the 2 clones increased as ieaf nitrogen increased. Thus, RCP37 had a higher photosynthetic nitrogen use efficiency than CA11. However, at a given applied nitrogen level, CA11 allocated more nitrogen to a unit of leaf area so that photosynthetic rates were higher than RCP37, except at the highest application of 300 mg ^l-1. The high nitrogen accumulation capacity and resource allocation to fruiting structures (crowns) in CA11 leads us to suggest that this clone may possess genes that could increase fruit yield in cultivated strawberry.     

Internal pH crisis, lysine decarboxylase and the acid tolerance response of Salmonella typhimurium

Salmonella typhimurium possesses an adaptive response to acid that increases survival during exposure to extremely low pH values. The acid tolerance response (ATR) includes both log-phase and stationary-phase systems. The log-phase ATR appears to require two components for maximum acid tolerance, namely an inducible pH homeostasis system, and a series of acid-shock proteins. We have discovered one of what appears to be a series of inducible exigency pH homeostasis systems that contribute to acid tolerance in extreme acid environments. The low pH-inducible lysine decarboxylase was shown to contribute significantly to pH homeostasis in environments as low as pH 3.0. Under the conditions tested, both lysine decarboxylase and σ^s-dependent acid-shock proteins were required for acid tolerance but only lysine decarboxylase contributed to pH homeostasis. The cadBA operon encoding lysine decarboxylase and a lysine/cadaverine antiporter were cloned from S. typhimurium and were found to be 79% homologous to the cadBA operon from Escherichia coli . The results suggest that S. typhimurium has a variety of means of fulfilling the pH homeostasis requirement of the ATR in the form of inducible amino acid decarboxylases.     

Cell separation from high cell density broths of Alcaligenes eutrophus by using a coagulant

Summary Alcaligenes eutrophus was successfully recovered from high cell density broths by pre-treatment with polyaluminium hydroxide chloride silicate as a coagulant at 36–90 mg Al/l. The optimum pH range for cell coagulation was 10–12. Subsequent centrifugation (45×g) and filtration (pore size 0.5 mm) gave a cell recovery of higher than 90%. The energy demand for cell recovery with the coagulant was only 3–11% of that without it.     

Enhancement of CO2 tolerance of Chlorella vulgaris by gradual increase of CO2 concentration

Summary Chlorella vulgaris UTEX259 was cultivated using two different methods of gas supply. In one method the CO₂ concentration in bubbled gas was held constant and in the other method it was increased gradually. Algal growth was almost linear after a short period of lag phase in both methods. With the constant CO₂ concentration, the CO₂ fixation rate in the linear growth phase decreased over 10%(v/v) CO₂, while the rate increased up to 6% CO₂. However, the rate was enhanced by using the latter incremental increase method, especially under a higher concentration of CO₂. The maximum rate of CO₂ fixation was 52 mg CO₂/l·h at 20% CO₂ during the gradual increase of CO₂ concentration.     

Use of moving aeration membrane bioreactor for the efficient production of tissue type plasminogen activator in serum free medium

A moving aeration-membrane (MAM) bioreactor was employed for the production of 2 μg/mL of tissue type Plasminogen Activator (tPA) in serum free medium from normal human fibroblast cells. This system could maintain high cell density for long periods of steady state conditions in perfusion cultivation. Under normal operating conditions, shear stress was as low as 0.65 dynes/cm² at the agitation speed of 80 rpm. Even though cell density gradually decreased with increasing agitation speed, tPA production increased linearly with increasing shear stress within a moderate range. This culture system allowed production of 2 μg tPA/mL while maintaining a high cell density of 1.0×10⁷ viable cells/mL.     

Host-cell cyclophilin is important for the intracellular replication of Leishmania major

The antiparasitic effects of cyclosporin A were examined in leishmanial infection by analysing the role of CsA-binding proteins (cyclophilins) in the host–parasite interaction. We hypothesized that the leishmanicidal effects of CsA on Leishmania major infected macrophages might be mediated through a cyclophilin of either the parasite or the host cell. Two cyclophilins (20 and 22 kDa) were purified from L. major parasites and N-terminally sequenced. Although enzyme activity of these cyclophilins was inhibited by CsA, pretreatment of L. major parasites with CsA did not result in reduction of a subsequent macrophage infection, arguing against a role of L. major cyclophilins as infectivity potentiators. However, host-cell cyclophilin A (CypA) was found to be critically involved in the intracellular replication of L. major parasites in murine macrophages. An antisense oligonucleotide to murine CypA was constructed and added to cultures of peritoneal macrophages prior to infection with L. major parasites. This treatment strongly reduced the expression of CypA in macrophages and resulted in the inhibition of the intracellular replication of L. major amastigotes. These data indicate that interaction of amastigotes with host-cell cyclophilin is an important part of the intracellular replication machinery of L. major and define, for the first time, a direct involvement of a cyclophilin in the survival strategies of an intracellular parasite.     

Establishment of the Dorso-ventral Axis in Xenopus Embryos Is Presaged by Early Asymmetries in β-Catenin That Are Modulated by the Wnt Signaling Pathway

Eggs of Xenopus laevis undergo a postfertilization cortical rotation that specifies the position of the dorso-ventral axis and activates a transplantable dorsal-determining activity in dorsal blastomeres by the 32-cell stage. There have heretofore been no reported dorso-ventral asymmetries in endogenous signaling proteins that may be involved in this dorsal-determining activity during early cleavage stages. We focused on β-catenin as a candidate for an asymmetrically localized dorsal-determining factor since it is both necessary and sufficient for dorsal axis formation. We report that β-catenin displays greater cytoplasmic accumulation on the future dorsal side of the Xenopus embryo by the two-cell stage. This asymmetry persists and increases through early cleavage stages, with β-catenin accumulating in dorsal but not ventral nuclei by the 16- to 32cell stages. We then investigated which potential signaling factors and pathways are capable of modulating the steady-state levels of endogenous β-catenin. Steadystate levels and nuclear accumulation of β-catenin increased in response to ectopic Xenopus Wnt-8 (Xwnt-8) and to the inhibition of glycogen synthase kinase-3, whereas neither Xwnt-5A, BVg1, nor noggin increased β-catenin levels before the mid-blastula stage. As greater levels and nuclear accumulation of β-catenin on the future dorsal side of the embryo correlate with the induction of specific dorsal genes, our data suggest that early asymmetries in β-catenin presage and may specify dorso-ventral differences in gene expression and cell fate. Our data further support the hypothesis that these dorso-ventral differences in β-catenin arise in response to the postfertilization activation of a signaling pathway that involves Xenopus glycogen synthase kinase-3.     

Crystallization,molecular replacement solution,and refinement of tetrameric β-amylase from sweet potato

Sweet potato β-amylase is a tetramer of identical subunits, which are arranged to exhibit 222 molecular symmetry. Its subunit consists of 498 amino acid residues (Mr 55,880). It has been crystallized at room temperature using polyethylene glycol 1500 as precipitant. The crystals, growing to dimensions of 0.4 mm × 0.4 mm × 1.0 mm within 2 weeks, belong to the tetragonal space group P4₂2₁2 with unit cell dimensions of a = b = 129.63 Å and c = 68.42 Å. The asymmetric unit contains 1 subunit of β-amylase, with a crystal volume per protein mass (V_M) of 2.57 ų/Da and a solvent content of 52% by volume. The three-dimensional structure of the tetrameric β-amylase from sweet potato has been determined by molecular replacement methods using the monomeric structure of soybean enzyme as the starting model. The refined subunit model contains 3,863 nonhydrogen protein atoms (488 amino acid residues) and 319 water oxygen atoms. The current R-value is 20.3% for data in the resolution range of 8–2.3 Å (with 2 σ cut-off) with good stereochemistry. The subunit structure of sweet potato β-amylase (crystallized in the absence of α-cyclodextrin) is very similar to that of soybean β-amylase (complexed with α-cyclodextrin). The root-mean-square (RMS) difference for 487 equivalent Cα atoms of the two β-amylases is 0.96 Å. Each subunit of sweet potato β-amylase is composed of a large (α/β)₈ core domain, a small one made up of three long loops [L3 (residues 91–150), LA (residues 183–258), and L5 (residues 300–327)], and a long C-terminal loop formed by residues 445–493. Conserved Glu 187, believed to play an important role in catalysis, is located at the cleft between the (α/β)₈ barrel core and a small domain made up of three long loops (L3, L4, and L5). Conserved Cys 96, important in the inactivation of enzyme activity by sulfhydryl reagents, is located at the entrance of the (α/β)₈ barrel. © 1995 Wiley-Liss, Inc.