New Species of Eimeria (Protozoa: Eimeriidae) from Malaysian Rats*

SYNOPSIS. Four new species of Eimeria were found in a survey of 255 rats of 14 species in Malaysia. E. tikusi n. sp. and E. edwardsi n. sp. are described from Edwards' rat Rattus edwardsi. The ellipsoidal, single-layered oocysts of E. tikusi average 30.3 by 24.4 μ. A micropyle is absent; a polar granule is present. Ovoid sporocysts average 14.2 by 9.8 μ. A sporocyst residuum and Stieda body are present. The ovoid, 2-layered oocysts of E. edwardsi average 29.1 by 21.8 μ. A micropyle is present; a polar granule is absent. Ellipsoidal to ovoid sporocysts average 14.5 by 6.5 μ. A sporocyst residuum is present; Stieda body is small or absent. E. surifer n. sp. is described from the red spiny rat Rattus surifer. Its ellipsoidal 3-layered oocysts average 34.7 by 24.8 μ. A micropyle is absent; a polar granule is present. The ellipsoidal sporocysts average 15.4 by 9.5 μ. A sporocyst residuum, Stieda body and sub-Stieda body are present. E. sabani n. sp. is described from the long-tailed giant rat R. sabanus. Its ellipsoidal 2-layered oocysts average 28.5 by 21.7 μ. A micropyle is absent; a polar granule is present. The ellipsoidal-to-ovoid sporocysts average 11.9 by 8.0 μ. A sporocyst residuum and Stieda body are present.     

Elicitor-specific induction of one member of the chitinase gene family in Arachis hypogaea

Summary Chitinases are believed to play an important role in plant defence against bacterial and fungal attack. In peanut (Arachis hypogaea) chitinase genes form a small multigene family. Four chitinase cDNAs (chit 1–4) were isolated from cultured peanut cells. Expression of individual chit genes was assayed by the polymerase chain reaction (PCR) followed by analysis of restriction fragment length polymorphisms (RFLP). UV irradiation, dilution of cell cultures and treatment with Phytophthora megasperma (Pmg) elicitor or yeast extract were used to induce expression of chit genes. The chit 3 gene is constitutively expressed at a low level in untreated as well as in treated cultures; the expression of chit 4 gene is induced by each of the stimuli tested, whereas the chit 1 gene is activated by cell culture dilution and by yeast extract treatment. The chit 2 gene is strongly activated by treatment with cell wall components from the fungus Phytophthora megasperma but not by the other stimuli. These results indicate that chit 2 gene expression may be controlled by pathogen-specific regulatory elements.     

Genetic basis of microbial carotenogenesis

The synthesis of carotenoids begins with the formation of a phytoene from geranylgeranyl pyrophosphate, a well conserved step in all carotenogenic organisms and catalyzed by a phytoene synthase, an enzyme encoded by the crtB (spy) genes. The next step is the dehydrogenation of the phytoene, which is carried out by phytoene dehydrogenase. In organisms with oxygenic photosynthesis, this enzyme, which accomplishes two dehydrogenations, is encoded by the crtP genes. In organisms that lack oxygenic photosynthesis, dehydrogenation is carried out by an enzyme completely unrelated to the former one, which carries out four dehydrogenations and is encoded by the crtI genes. In organisms with oxygenic photosynthesis, dehydrogenation of the phytoene is accomplished by a ζ-carotene dehydrogenase encoded by the crtQ (zds) genes. In many carotenogenic organisms, the process is completed with the cyclization of lycopene. In organisms exhibiting oxygenic photosynthesis, this step is performed by a lycopene cyclase encoded by the crtL genes. In contrast, anoxygenic photosynthetic and non-photosynthetic organisms use a different lycopene cyclase, encoded by the crtY (lyc) genes. A third and unrelated type of lycopene β-cyclase has been described in certain bacteria and archaea. Fungi differ from the rest of non-photosynthetic organisms in that they have a bifunctional enzyme that displays both phytoene synthase and lycopene cyclase activity. Carotenoids can be modified by oxygen-containing functional groups, thus originating xanthophylls. Only two enzymes are necessary for the conversion of β-carotene into astaxanthin, using several ketocarotenoids as intermediates, in both prokaryotes and eukaryotes. These enzymes are a β-carotene hydroxylase (crtZ genes) and a β-carotene ketolase, encoded by the crtW (bacteria) or bkt (algae) genes. Electronic Publication     

Ecology of a paramo cushion mire

Abstract. The vegetation ecology of a paramo cushion mire was studied along four transects. Six local vegetation types were distinguished. Two types are called cushion bogs; one is dominated by Oreobolus cleefii and the other by Plantago rigida. Types 3 and 4 are mire vegetation dominated by bryophytes; one is characterised by Sphagnum sparsum, Breutelia sp. and Campylopus cucullatifolius, the other one is dominated by Lophozia subinflata with Cortaderia sericantha. Vegetation type 5 is dominated by submerged Sphagnum cyclophyllum; type 6 refers to aquatic vegetation with only Equisetum bogotense and algae. The relation between the first four vegetation types and edaphical and hydrological gradients is analysed by means of Canonical Correspondence Analysis (CCA). From the results of CCA it can be concluded that the occurrence of the Oreobolus cleefii type is restricted to areas with a thinner peat layer, a wider distance surface-anaerobic zone and water table-anaerobic zone, a higher NO₂ concentration and a lower pH. The occurrence of the Plantago rigida type is restricted to a situation with a lower electrical conductivity of the ground water, a lower NO₃ and PO₄ concentration, and a higher Fe concentration. The occurrence of the Sphagnum type is restricted to places with a higher conductivity of the ground water, a higher NO₃ and PO₄ concentration, and a lower Fe concentration. The occurrence of the Lophozia subinflata with Cortaderia sericantha type is restricted to a situation with a lower K and Al concentration.     

Photoperiodic Control of Developmental Diapause in Nymphs of Prostriate Ixodid Ticks (Acari: Ixodidae)

Extrinsic control of developmental diapause in nymphs of prostriate ticks of the subgenus Ixodes sensu stricto (Ixodes ricinus and Ixodes persulcatus from Eurasia and Ixodes scapularis from North America) appears to be based on a complex two-step photoperiodic reaction of a short-day/long-day type. Diapause control in the subgenus Afrixodes (the South African tick Ixodes rubicundus) appears to be based on a simple long-day reaction. The option between non-diapause development and diapausing arrest in engorged nymphs is determined by both pre- and post-feeding photoperiodic regimes. Consequently diapausing arrest in engorged nymphs of Ixodes sensu stricto can be induced either by a short-day (after their engorgement) or by a long-day regime (in unfed nymphs), while active, non-diapause development is possible only when the short-day pre-feeding regime is followed by a long-day post-feeding regime. The photoperiodic response in I. (Afrixodes) rubicundus nymphs seems to be of the long-day type both before and after feeding. Consequently this non-diapause development is enabled by a long-day regime, while diapause is induced by a short-day regime of exposure. Nevertheless, there are some indications that the control of nymphal diapause in the latter species is also of a complex nature. This revised version was published online in July 2006 with corrections to the Cover Date.     

Cloning and molecular characterisation of the amdR controlled gatA gene of Aspergillus nidulans

Summary The gamma-amino-n-butyrate transaminase gene (gatA) of Aspergillus nidulans is one of several genes under positive control by the regulatory gene amdR (also called intA). The gatA gene has been cloned from a cosmid library by complementation of a gatA mutation. The sequence of a 2.6 kb genomic fragment containing gatA has been determined. An open reading frame of 1497 bp within this sequences is interrupted by three putative introns and predicts a protein of 55 kDa. Northern analysis confirms control of gatA RNA levels by amdR and also indicates that gatA is not strongly regulated by areA-mediated nitrogen metabolite repression. A. nidulans transformants containing multiple copies of a plasmid carrying an 88 bp fragment from the 5 untranscribed region of gatA grew poorly on substrates whose utilisation is dependent on genes controlled by amdR. This indicated titration of limiting amounts of the amdR gene product by this 88 bp fragment. Comparison of this sequence with the 5 region of the coregulated gene, amdS, reveals probable sites of action for the amdR protein.     

Expression of the apoptosis inducer gene head involution defective in primordial germ cells of the Drosophila embryo requires eiger,p53, and loki function

Nanos (Nos) is an evolutionarily conserved protein essential for the maintenance of primordial germ cells (PGCs). In Drosophila, the PGCs or pole cells express head involution defective (hid), which is required for caspase activation, but its translation is repressed by maternal Nos. In the absence of Nos activity, translation of hid mRNA into protein induces apoptosis in pole cells. However, it remains unclear how hid mRNA is regulated in pole cells. Here, we report that hid expression requires eiger (egr), a tumor necrosis factor ligand (TNF) homologue, which is induced in pole cells by decapentaplegic (dpp). In addition, we demonstrate that p53 and loki (lok), a damage‐activated kinase known to be required for p53 phosphorylation, are both required for hid expression in pole cells. Since maternal lok mRNA is enriched in pole cells, it is possible that ubiquitously distributed p53 is activated in pole cells by maternal Lok. We propose that hid expression is activated in a pole cell‐specific manner by loki/p53 and dpp/egr during embryogenesis.     

Kinetics of formation of fibrin oligomers. I. Theory

The course of formation of fibrin oligomers is treated theoretically for the condition that self-assembly of fibrin monomers is rapid compared with the loss of A peptides by the enzymatic action of thrombin. The rate constant for removal of the second A peptide is taken to be larger than that for the first by an arbitrary factor q; the association of activated A sites with their complementary a sites is assumed to be random and independent of oligomer size. Two types of oligomers are considered: noncovalently bonded protofibrils formed by the staggered overlap of thrombin-activated monomers and covalently bonded linear oligomers formed by factor XIIIa-mediated end-to-end ligation of adjacent monomers within protofibrils. Oligomers of the first type, if ligated, are dissociated to oligomers of the second type by solubilization in SDS–urea. Theoretical curves are presented for x _w and x ′_w (weight-average degree of polymerization of staggered overlap and linear ligated oligomers, respectively) and for the weight fractions of monomer, dimer, and decamer of both ligated and unligated species as functions of y, the fraction of A peptide removed; and also for w_x and w′_x, the weight fractions of x-mer of the respective oligomer types, as a function of x at y = 0.5. With increasing q, the maximum w_x or w′_x that a low oligomer will reach during the reaction decreases and the size distribution is broadened toward larger oligomers. Comparison with experiment is made in a companion paper.     

Role of Pseudomonas fluorescens and INA against Black Rot of Cabbage

Cabbage (Brassica oleracea var. capitata) is an important vegetable crop among crucifers. It is affected by a bacterial disease known as black rot. Black rot is caused by Xanthomonas campestris pv. campestris a disease of worldwide importance. The present study highlights the effect of biotic inducer—Pseudomonas fluorescens—and an abiotic inducer—2,6‐dichloro‐isonicotinic acid—in combating black rot, followed by their effect on the seed treatment and disease incidence, role of antioxidant enzymes followed by validation of the defence‐related genes by quantitative real‐time PCR. The resistant (Pusa mukta) and the highly susceptible (NBH boss) cabbage cultivars were analysed for defence‐related enzymes such as peroxidase and superoxide dismutase. An increase in total peroxidase and superoxide dismutase activity was observed upon inoculation with X. campestris pv. campestris. The activity was greater in resistant cultivar when compared to susceptible ones. Both enzyme activity assays and qPCR analyses for the expression of the defence genes in susceptible and resistant cultivars demonstrated that the peroxidase gene was up‐regulated in resistant cultivar compared to susceptible cultivar. The present study proved that P. fluorescens‐induced resistance against X. campestris pv. campestris in cabbage seedlings is more efficient as compared to the use of INA—abiotic inducer.     

Lmbrd1 expression is essential for the initiation of gastrulation

The rare inborn cblF defect of cobalamin metabolism is caused by mutations in the limb region 1 (LMBR1) domain containing 1 gene (LMBRD1). This defect is characterized by massive accumulation of free cobalamin in lysosomes and loss of mitochondrial succinyl‐CoA synthesis and cytosolic methionine synthesis. Affected children suffer from heart defects, developmental delay and megaloblastic anemia. LMBRD1 encodes for LMBD1, a predicted lysosomal cobalamin transport protein. In this study, we determine the physiological function of LMBRD1 during embryogenesis by generating Lmbrd1 deficient mice using the Cre/LoxP system. Complete loss of Lmbrd1 function is accompanied by early embryonic death in mice. Whole mount in situ hybridization studies against bone morphogenetic protein 4 and Nodal show that initial formation of the proximal–distal axis is unaffected in early embryonic stages whereas the initiation of gastrulation is disturbed shown by the expression pattern of even skipped homeotic gene 1 and fibroblast growth factor 8 in Lmbrd1 deficient mice. We conclude that intact function of LMBD1 is essential for the initiation of gastrulation.     

Regulation of the trimethylamine N-oxide (TMAO) reductase in Escherichia coli: analysis of tor::Mud1 operon fusion

Summary Mud1 insertion mutants of Escherichia coli were obtained in which the lac structural genes were fused to the promoter of torA, a gene encoding the trimethylamine N-oxide (TMAO) reductase. Expression of the fusion is induced by TMAO and repressed by oxygen. However, in contrast to the nar operon which codes for the nitrate reductase structural genes, the tor::Mud1 fusion was found to be independent of the positive control exerted by the nirR gene product and not repressed by the molybdenum cofactor. The torA gene which is strongly linked to pyrF (28.3 U) is different from any tor gene already described in E. coli or in Salmonella typhimurium.     

Coformational aspects of polypeptide structure XL. The synthesis of poly((S)-thiazolidine-4-carboxylic acid)

The synthesis of poly[(S)-thiazolidine-4-carboxylic acid] is described. The polymer is obtained by the polymerization of the N-carboxyanhydride of (S)-thiazolidine-4-carboxylic acid in pyridine or nitrobenzene using triethylamine as an initiator. The amino acid is prepared by the condensation of cysteine and formaldehyde. N-Acetyl-(S)-thiazolidine-4-carboxylic acid methyl ester is also prepared as a model compound by standard acetylation and esterification reactions.     

Nutrient content of the aquatic macrophytesElodea canadensis andCeratophyllum in the course of the year

Summary In Lake Vechten, a sandpit near the city of Utrecht (The Netherlands), the submerged macrophyte vegetation is dominated by two species, namelyCeratophyllum demersum andElodea canadensis. In the course of the year both species are able to develop two distinct forms: the normal vegetative form in summer, the dormant form in winter.Elodea is anchored to the substrate by roots,Ceratophyllum by modified leaves, called rhizoids by GLÜCK (1906, 1911). Both species form distinct zones. The depth at which the plants occur abundantly is 0 to 3 m in the case ofElodea and from 3 to 5 forCeratophyllum.     

Molecular analysis of theBg-rbg transposable element system ofZea mays L.

Summary The two components of theBg-rbg transposable element system of maize have been cloned. TheBg element, isolated from the mutable allelewx-m32 :: Bg is inserted in the intron of theWaxy (Wx) gene between exons 12 and 13. The length of the element is of 4869 bp.Bg has 5 by terminal inverted repeats, and generates upon insertion an 8 by direct duplication of the target sequence. Both ends of theBg element contain a 76 by direct repeat adjacent to the terminal inverted repeats. The hexamer motif TATCG_kC ^G is here repeated several times in direct or inverse orientation. Therbg element was isolated from the mutable alleleo2m(r) where it is located in the promoter region of theOpaque-2 (O2) gene.rbg is approximately 4.5 kb in length, has terminal inverted repeats identical to those of theBg element, and is also flanked by an 8 by direct duplication at the target site. LikeBg, rbg carries the 76 by direct repeats. Restriction enzyme analysis reveals that, compared toBg, the receptor element is distinguishable by small deletion and insertion events. Sequence data indicate that not more than 75% homology exists at the DNA level between therbg element and the autonomousBg element.     

Comprehensive pyrosequencing analysis of the bacterial microbiota of the skin of patients with seborrheic dermatitis

Seborrheic dermatitis (SD) is a chronic inflammatory dermatologic condition in which erythema and itching develop on areas of the body with sebaceous glands, such as the scalp, face and chest. The inflammation is evoked directly by oleic acid, which is hydrolyzed from sebum by lipases secreted by skin microorganisms. Although the skin fungal genus, Malassezia, is thought to be the causative agent of SD, analysis of the bacterial microbiota of skin samples of patients with SD is necessary to clarify any association with Malassezia because the skin microbiota comprises diverse bacterial and fungal genera. In the present study, bacterial microbiotas were analyzed at non‐lesional and lesional sites of 24 patients with SD by pyrosequencing and qPCR. Principal coordinate analysis revealed clear separation between the microbiota of non‐lesional and lesional sites. Acinetobacter, Corynebacterium, Staphylococcus, Streptococcus and Propionibacterium were abundant at both sites. Propionibacterium was abundant at non‐lesional sites, whereas Acinetobacter, Staphylococcus and Streptococcus predominated at lesional sites; however, the extent of Propionibacterium colonization did not differ significantly between lesional and non‐lesional sites according to qPCR. Given that these abundant bacteria hydrolyze sebum, they may also contribute to SD development. To the best of our knowledge, this is the first comprehensive analysis of the bacterial microbiotas of the skin of SD patients.     

Regulation of the phosphate regulon of Escherichia coli: Characterization of the promoter of the pstS gene

Summary The pstS gene belongs to the phosphate regulon whose expression is induced by phosphate starvation and regulated positively by the PhoB protein. The phosphate (pho) box is a consensus sequence shared by the regulatory regions of the genes in the pho regulon. We constructed two series of deletion mutations in a plasmid in vitro, with upstream and downstream deletions in the promoter region of pstS, which contains two pho boxes in tandem, and studied their promoter activity by connecting them with a promoterless gene for chloramphenicol acetyltransferase. Deletions extending into the upstream pho box but retaining the downstream pho box greatly reduced promoter activity, but the remaining activity was still regulated by phosphate levels in the medium and by the PhoB protein, indicating that each pho box is functional. No activity was observed in deletion mutants which lacked the remaining pho box or the-10 region. Therefore, the pstS promoter was defined to include the two pho boxes and the-10 region. The PhoB protein binding region in the pstS regulatory region was studied with the deletion plasmids by a gelmobility retardation assay. The results suggest the protein binds to each pho box on the pstS promoter. A phoB deletion mutant was constructed, and we demonstrated that expression of pstS was strictly dependent on the function of the PhoB protein.