Observations on the flagellar apparatus of a coccolithophorid,Cruciplacolithus neohelis (Prymnesiophyceae)

The flagellar apparatus ofCruciplacolithus neohelis (McIntyre and Bé) Reinhardt including its transition region is described. The transition region contains a hat-shaped structure, which is suggested to be one of the common features of the Prymnesiophyceae. Its flagellar root system resembles that of most coccolithophorids examined so far, except that only one vestigial crystalline root is present associated with root 1. Two well-developed crystalline roots associated with roots 1 and 2, respectively, appear in the preprophase of nuclear division, suggesting conversion to a mitotic spindle. The taxonomic and evolutionary significance of the flagellar apparatus is discussed.     

A Strain of Bacillus thuringiensis for the Control of Plant‐parasitic Nematodes

An isolate of Bacillus thuringiensis, designated CR‐371, was evaluated for efficacy in controlling plant‐parasitic nematodes. This isolate was first shown to be nematicidal to Caenorhabditis elegans in an in vitro laboratory assay. Treatment resulted in a significant reduction in galls due to root‐knot nematode on tomato in a greenhouse trial. In two field trials in Puerto Rico, CR‐371‐treated tomatoes and pepper had significantly fewer root galls due to Meloidogyne incognita than untreated controls, and populations of Rotylenchulus reniformis were smaller. In one experiment, CR‐371 treatment was associated with significant increases in pepper yields, while in the second trial small yield increases of pepper and tomato occurred. In a greenhouse trial, incorporation of CR‐371 into a methyl cellulose seed coat gave similar control of root‐knot nematode on tomato as compared to CR‐371 applied as a drench. CR‐371‐treated strawberry plants also had smaller populations of Pratylenchus penetrans in roots in a greenhouse trial in Massachusetts.     

Application of Chaos Theory in Analyzing the Cardiac Rhythm in Healthy Subjects at Different Sleep Stages

The changes in the chaotic element of the cardiac rhythm (CR) were quantitated at different sleep stages by calculating the correlation dimension (D2) in 26 healthy subjects of both sexes (mean age 29.2 years), including 7 trained and 19 untrained subjects. Three untrained subjects took part in tests with autonomic nervous system blockers (atropine and propranolol). The study demonstrated a correlation between the changes in D2 at different sleep stages and the level of the autonomic regulation of CR. As the influence of the parasympathetic system on CR increased from one stage of slow wave sleep to another, D2 increased; during rapid eye movement (REM) sleep, this influence weakened and D2 decreased. The character of changes differed in the trained and untrained subjects and depended on the initial level of the autonomic regulation of CR. In the trained subjects, characterized by predominance of the parasympathetic regulation of CR, the initial and subsequent D2 values were higher than in the untrained subjects. Both during wakefulness and at all stages of sleep, D2 increased when the sympathetic regulation of CR was blocked, decreased when the parasympathetic regulation was blocked, and reached the lowest level when both of them were blocked. This showed that the chaotic element of CR, expressed numerically by D2, depends on the regulating effects of the autonomic nervous system.     

Attractiveness of the maleAcheta domestica calling song to females

Summary FemaleAcheta domestica did not discriminate between pairs of model calling songs (CSs) which differed only in syllable period (SP; Fig. 1). The females selected the louder CS (Fig. 2) or the CS with a faster chirp rate (CR; Fig. 3) when presented with pairs of otherwise identical CSs. A CS with an SP of 50 ms (modal for the male's CS) was preferred when it was 5 dB louder than one with a 60-ms SP while a CS with a 60-ms SP was only consistently chosen when it was 10 dB louder than a CS with a 50-ms SP (Fig. 4). A more intense CS was preferred by the females regardless of whether its CR was faster or slower than that of the CS produced at a lower intensity (Fig. 6). When CSs with SPs of 50 or 60 ms had several different CRs, the females that made a significant choice preferred a CS with a 50-ms SP regardless of whether it was produced at a faster or slower CR (Figs. 7, 8). No significant selection between CSs with 40- and 50-ms SPs resulted when they were produced at different intensities (Fig. 5) or CRs (Fig. 9). Females only significantly chose a CS with a 50-ms SP over those with 40 ms SPs when the 50-ms-SP CS was louder and produced at a different CR (Fig. 10). From these results, it was apparent that SP, intensity, and CR all influenced a female's choice of a CS, and thus the male producing it. However, our results indicate that SP was the most important feature influencing the female's choice and that intensity was more effective than CR.Abbreviations CR chirp rate - CS calling song - POD polar orientation diagram - SP syllable period     

CRD1, an Xpo1 domain protein,regulates miRNA accumulation and crown root development in rice

Crown root (CR) is the main component of the fibrous root system in cereal crops, but the molecular mechanism underlying CR development is still unclear. Here, we isolated the crown root defect 1 (crd1) mutant from ethyl methane sulfonate‐mutated mutant library, which significantly inhibited CR development. The CRD1 was identified through genome resequencing and complementation analysis, which encodes an Xpo1 domain protein: the rice ortholog of Arabidopsis HASTY (HST) and human exportin‐5 (XPO5). CRD1 is ubiquitously expressed, with the highest expression levels in the CR primordium at the stem base. CRD1 is a nucleocytoplasmic protein. The crd1 mutant contains significantly reduced miRNA levels in the cytoplasm and nucleus, suggesting that CRD1 is essential for maintaining normal miRNA levels in plant cells. The altered CR phenotype of crd1 was simulated by target mimicry of miR156, suggesting that this defect is due to the disruption of miR156 regulatory pathways. Our analysis of CRD1, the HST ortholog identified in monocots, expands our understanding of the molecular mechanisms underlying miRNA level and CR development.     

Calorie restriction effects on silencing and recombination at the yeast rDNA

Aging research has developed rapidly over the past decade, identifying individual genes and molecular mechanisms of the aging process through the use of model organisms and high throughput technologies. Calorie restriction (CR) is the most widely researched environmental manipulation that extends lifespan. Activation of the NAD⁺‐dependent protein deacetylase Sir2 (S ilent I nformation R egulator 2) has been proposed to mediate the beneficial effects of CR in the budding yeast Saccharomyces cerevisiae, as well as other organisms. Here, we show that in contrast to previous reports, Sir2 is not stimulated by CR to strengthen silencing of multiple reporter genes in the rDNA of S. cerevisiae. CR does modestly reduce the frequency of rDNA recombination, although in a SIR2‐independent manner. CR‐mediated repression of rDNA recombination also does not correlate with the silencing of Pol II‐transcribed noncoding RNAs derived from the rDNA intergenic spacer, suggesting that additional silencing‐independent pathways function in lifespan regulation.     

Mycorrhizal influence on protein and lipid of durum wheat grown at different soil phosphorus levels

 Root colonization by arbuscular mycorrhizal fungi (AMF) may affect protein and lipid composition of plants by altering P nutrition or by eliciting other metabolic responses in the host plant. This study was conducted to determine the effects of an AMF and soil P on seed protein and lipid contents and yield of two genotypes of durum wheat (Triticum durum L.). Plants were grown in a greenhouse using soil: sand mixes with different levels of P, and with or without the AMF Glomus mosseae [(Nicol. and Gerd.) Gerd. and Trappe]. Percentage AMF root colonization decreased as P added to soil increased. The wheat genotype CR057 had higher AMF root colonization but lower seed P and protein concentrations than CR006. Without added soil P, protein concentration was significantly lower and lipid concentration and seed dry weight higher in arbuscular mycorrhizal (AM) than in nonAM plants. Seed lipid and protein contents were highly correlated with P content of plants. In nonAM plants, seed lipid and protein contents were low with no added soil P and did not differ with added soil P. Seed protein/lipid (Pro/L) concentration ratios of AM plants were higher than those of nonAM plants only when no P was added to the soil. The data indicate different patterns of seed P accumulation and different relationships between seed P and protein and lipid in AM and nonAM plants. Thus, both the presence and degree of AMF root colonization affected seed lipid metabolism in these durum wheat genotypes. Accepted: 18 May 1999     

Transformation of the flagella and associated flagellar components during cell division in the coccolithophoridPleurochrysis carterae

Summary Immunofluorescence microscopy, conventional and high voltage transmission electron microscopy were used to describe changes in the flagellar apparatus during cell division in the motile, coccolithbearing cells ofPleurochrysis carterae (Braarud and Fagerlund) Christensen. New basal bodies appear alongside the parental basal bodies before mitosis and at prophase the large microtubular (crystalline) roots disassemble as their component microtubules migrate to the future spindle poles. By prometaphase the crystalline roots have disappeared; the flagellar axonemes shorten and the two pairs of basal bodies (each consisting of one parental and one daughter basal body) separate so that each pair is distal to a spindle pole. By late prometaphase the pairs of basal bodies bear diminutive flagellar roots for the future daughter cells. The long flagellum of each daughter cell is derived from the parental basal bodies; thus, the basal body that produces a short flagellum in the parent produces a long flagellum in the daughter cell. We conclude that each basal body in these cells is inherently identical but that a first generation basal body generates a short flagellum and in succeeding generations it produces a long flagellum. At metaphase a fibrous band connecting the basal bodies appears and the roots and basal bodies reorient to their interphase configuration. By telophase the crystalline roots have begun to reform and the rootlet microtubules have assumed their interphase appearance by early cytokinesis.Abbreviations CR1, CR2 crystalline roots 1 and 2 - CT cytoplasmic tongue microtubules - DIC differential interference contrast light microscopy - H haptonema - HVEM high voltage transmission electron microscopy - IMF immunofluorescence microscopy - L left flagellum/basal body - M metaphase plate - MT microtubule - N nucleus - R right flagellum/basal body - R1, R2, R3 roots 1, 2, and 3 - TEM transmission electron microscopy     

A re‐assessment of sucrose signaling involved in cluster‐root formation and function in phosphate‐deficient white lupin (Lupinus albus)

Apart from substrate functions, a signaling role of sucrose in root growth regulation is well established. This raised the question whether sucrose signals might also be involved in formation of cluster‐roots (CRs) under phosphate (Pi) limitation, mediating exudation of phosphorus (P)‐mobilizing root exudates, e.g. in Lupinus albus and members of the Proteaceae. Earlier studies demonstrated that CR formation in L. albus was mimicked to some extent by external application of high sucrose concentrations (25 mM) in the presence of extremely high P supply (1–10 mM), usually suppressing CR formation. In this study, we re‐addressed this question using an axenic hydroponic culture system with normal P supply (0.1 mM) and a range of sucrose applications (0.25–25 mM). The 2.5 mM sucrose concentration was comparable with internal sucrose levels in the zone of CR initiation in first‐order laterals of P‐deficient plants (3.4 mM) and induced the same CR morphology. Similar to earlier studies, high sucrose concentrations (25 mM) resulted in root thickening and inhibition of root elongation, associated with a 10‐fold increase of the internal sucrose level. The sucrose analog palatinose and a combination of glucose/fructose failed to stimulate CR formation under P‐sufficient conditions, demonstrating a signal function of sucrose and excluding osmotic or carbon source effects. In contrast to earlier findings, sucrose was able to induce CR formation but had no effect on CR functioning with respect to citrate exudation, in vitro activity and expression of genes encoding phosphoenolpyruvate carboxylase, secretory acid phosphatase and MATE transporters, mediating P‐mobilizing functions of CRs.     

Impact of auxin-compounds produced by the antagonistic fungus Pythium oligandrum or the minor pathogen Pythium group F on plant growth

Plant growth promotion induced by the antagonistic fungus, Pythium oligandrum, is the result of a complex interaction which includes an indirect effect through control of pathogens in the rhizosphere and/or a direct one mediated by plant-induced resistance. The present study shows an increased plant growth associated with direct interaction between P. oligandrum and roots, which is mediated by a fungus-produced auxin compound, tryptamine (TNH₂). In vitro experiments provided evidence that P. oligandrum metabolised specifically indole derivatives, such as tryptophan and indole-3-acetaldehyde, to produce THN₂ through the tryptamine pathway. When P. oligandrum grew in sterile root exudates, it also produced an auxin-like compound. Additional experiments on P. oligandrum–root interaction showed that, in amended nutrient solution of plants, the antagonist metabolised Trp into TNH₂ and that root absorption of this newly formed auxin-compound in appropriate concentrations was associated with enhancement of plant growth. This phenomenon was observed only when nutrient solution was amended with low tryptophan (Trp) concentrations, i.e. 0.05 and 0.1 mM; higher concentration (0.5 and 1 mM Trp) induced abnormal root development. Similar experiments were performed with Pythium group F, a minor pathogen known for its ability to produce auxin-compounds through the tryptamine pathway. In this case, irregular root development was always noticed with all Trp concentrations added to the nutrient solution of plants. Moreover, Pythium group F colonization of roots was associated with leakage of auxin-compounds in the nutrient solution. Our results, therefore, highlight that the production of similar auxin-compounds by two Pythium species has contrary effects on plant development.     

p-Hydroxybenzoic Acid, a Growth Regulator, Isolated from Woody Cuttings of Ribes rubrum

Woody cuttings of Ribes rubrum, an easy plant to root, were extracted with methanol. One fraction of this extract was both water and ether soluble; a part of it was only water soluble. From the water and ether soluble fraction a crystalline compound was isolated which was fully identified with p-hydroxybenzoic acid (PHB) by m.p., mixed m.p., infrared spectrum, ultraviolet absorption in neutral and alkaline methanol and chemical analyses. For Avena coleoptiles straight growth test, p-hydroxyhenzoic acid was found to have a significant growth promoting activity in the range 20–100 μg/ml. and it showed strong growth inhibition at concentrations higher than 200 μg/ml. From the same extract fraction a phenolic ester was isolated by paper chromatography which showed a weak growth inhibiting activity. This compound was identified as an ester of p-hydroxybenzoic acid by micro-scale reactions. From the extract soluble only in water further amounts of crystalline p-hydroxybenzoic acid were obtained by alkaline hydrolysis. This PHB may have arisen from the breakdown of pelargonidin glucosides.     

Overexpression of CYB5R3 and NQO1, two NAD+‐producing enzymes,mimics aspects of caloric restriction

Calorie restriction (CR) is one of the most robust means to improve health and survival in model organisms. CR imposes a metabolic program that leads to increased stress resistance and delayed onset of chronic diseases, including cancer. In rodents, CR induces the upregulation of two NADH‐dehydrogenases, namely NAD(P)H:quinone oxidoreductase 1 (Nqo1) and cytochrome b₅ reductase 3 (Cyb5r3), which provide electrons for energy metabolism. It has been proposed that this upregulation may be responsible for some of the beneficial effects of CR, and defects in their activity are linked to aging and several age‐associated diseases. However, it is unclear whether changes in metabolic homeostasis solely through upregulation of these NADH‐dehydrogenases have a positive impact on health and survival. We generated a mouse that overexpresses both metabolic enzymes leading to phenotypes that resemble aspects of CR including a modest increase in lifespan, greater physical performance, a decrease in chronic inflammation, and, importantly, protection against carcinogenesis, one of the main hallmarks of CR. Furthermore, these animals showed an enhancement of metabolic flexibility and a significant upregulation of the NAD⁺/sirtuin pathway. The results highlight the importance of these NAD⁺ producers for the promotion of health and extended lifespan.     

Tolerance and avoidance of Al toxicity by Mucuna pruriens var. utilis at different levels of P supply

Previous laboratory experiments showed that velvet bean Mucuna pruriens is moderately tolerant to the presence of Al (up to 185 µM) in the root environment, but that it only develops a shallow root system in acid soils. Field experiments showed that Mucuna can tolerate acid subsoil conditions in a homogeneous root environment, but avoids subsoil if topsoil is present. Subsequent split-root experiments with a recirculating nutrient solution showed that this subsoil avoidance may be based on an Al avoidance mechanism in the root system. This Al avoidance mechanism, however, was not evident when phosphorus (P) supply to the whole plant was adequate. We thus hypothesized that surface application of P may help to overcome Al avoidance in the subsoil.In a field experiment on an ultisol in Lampung (Indonesia), only a moderate increase in aboveground biomass production was found for a wide range of P application rates, although the soil was low in available P, and the P adsorption isotherm was very steep. An increased P status of the topsoil and an increased P concentration in the aboveground biomass (from 50 to 75 mmol kg^-1) had no effect on root development in the subsoil.     

Fragments of Tenebrio molitor cadherin enhance Cry3Aa toxicity for the red flour beetle,Tribolium castaneum (Herbst)

Bacillus thuringiensis crystalline (Cry) proteins are highly toxic to a wide range of insect pests, but some species resist their action. This is true for many economically important beetles, including stored product pests, such as Tribolium castaneum. In this article, we show that the susceptibility of T. castaneum larvae to natural as well as to a recombinant Cry3Aa‐type toxin, applied in the diet, is enhanced by supplementing the diet with recombinant fragments of Tenebrio molitor cadherin; Cry toxin‐binding sites occur in several cadherin repeats (CR). In our study, we used the toxin‐binding region CRtb, which represents a substantial part of the repeat CR12‐MPED (membrane‐proximal extracellular domain). CRtb and CR12‐MPED consistently increased Cry3Aa toxicity. This synergistic effect occured at diverse mass ratios between the toxin and the cadherin fragments, suggesting that optimal ratios can be found. In our 6‐week‐long assay with T. castaneum, we achieved mortality of up to 96.6% with toxin concentration 30 μg/g. Cadherin fragments CR11 and CR9‐11 elicited small and diverse effects that require further analysis.     

Association of Common Polymorphisms in the Fractalkine Receptor (CX3CR1) With Obesity

The inflammatory component in obesity is now well established. The CX3CR1 gene encodes the fractalkine (CX3CL1) receptor and has two coding single‐nucleotide polymorphisms, V249I and T280M, linked to a lower risk of other inflammatory diseases such as coronary artery disease (CAD) and asthma. To determine whether CX3CR1 is associated with obesity, we genotyped the V249I and T280M polymorphisms of the CX3CR1 gene in subjects with a BMI ≥30 kg/m² and nonobese controls with a BMI <30 kg/m². Binary logistic regression analyses revealed that the 280MM genotype was associated with obesity (P = 0.022). A gender‐specific one‐way ANOVA was also conducted to investigate mean BMI and waist circumference differences between genotypes of each polymorphism. For both polymorphisms independently, women carrying two copies of the minor allele had significant higher mean waist circumference than those carrying only one copy of the minor allele (MM > TM, P = 0.031; II > VI, P = 0.013) or those who were homozygous for the major allele (MM > TT, P = 0.005; II > VV, P = 0.006). We also observed significant higher mean waist circumference in men carrying one copy of the minor allele when compared to those who were homozygous for the major allele for the T280M polymorphism (TM > TT, P = 0.029). This study suggests that CX3CR1, a biomarker of obesity in this sample, constitutes a potential target for further investigation of the role of inflammation in the expression of obesity‐related phenotypes.     

Further Studies on Guinea Pig Z-1 Antigen That Is Involved in Phagocytosis of Zymosan by Macrophages: Cell Type Distribution of the Antigen and Cross-Reactivity of Anti-Z-1 with Human CR3

We have previously identified a heterodimer molecule, Z-1, on guinea pig peritoneal macrophages (Møs) by the newly prepared monoclonal antibody, anti-Z-1, and Z-1 has been assumed to be the complement receptor type three (CR3) in this species. To clarify this assumption, the cell type distribution of the antigen in guinea pig and the cross-reactivity of anti-Z-1 with other species were analyzed. It was demonstrated that Z-1 was expressed on peritoneal Møs, pulmonary Møs, peritoneal polymorphonuclear leukocytes (PMN), peripheral neutrophils, and some subpopulations of spleen cells and of bone marrow cells, but not on erythrocytes, circulating lymphocytes, and lymphocytes in both spleen and bone marrow in detectable amounts. Thus the expression of Z-1 seems to be restricted to phagocytes as is CR3 of other species. Furthermore, it was found that anti-Z-1 bound with peripheral neutrophils from human, horse and goat and HL-60 cells differentiated into monocytes. Any cross-reactivity of the antibody was not detected with neutrophils from rabbit, cow, sheep and dog and nondifferentiated HL-60 cells. Human Z-1 was indistinguishable from human CR3, since both were the heterodimer consisting of α chain of 170 kDa (pI = 6.6-7.2) noncovalently associated with β chain of 100 kDa (pI = 5.6-6.7). In addition, human CR3 in detergent-lysate of neutrophils was completely adsorbed with anti-Z-1 F(ab')2-Sepharose. These findings indicate that guinea pig Z-1 shares an antigenic determinant with human CR3. It thus seems to be possible that Z-1 may function as CR3 in guinea pigs.     

Calorie restriction reduces rDNA recombination independently of rDNA silencing

Calorie restriction (CR) extends lifespan in yeast, worms, flies and mammals, suggesting that it acts via a conserved mechanism. In yeast, activation of the NAD‐dependent histone deacetylase, Sir2, by CR is thought to increase silencing at the ribosomal DNA, thereby reducing the recombination‐induced generation of extrachromosomal rDNA circles, hence increasing replicative lifespan. Although accumulation of extrachromosomal rDNA circles is specific to yeast aging, it is thought that Sirtuin activation represents a conserved longevity mechanism through which the beneficial effects of CR are mediated in various species. We show here that growing yeast on 0.05 or 0.5% glucose (severe and moderate CR, respectively) does not increase silencing at either sub‐telomeric or rDNA loci compared with standard (2% glucose) media. Furthermore, rDNA silencing was unaffected in the hxk2Δ, sch9Δ and tor1Δ genetic mimics of CR, but inhibited by FOB1 deletion. All these interventions extend lifespan in multiple yeast backgrounds, revealing a poor correlation between rDNA silencing and longevity. In contrast, CR and deletion of the FOB1, HXK2, SCH9 and TOR1 genes, all significantly reduced rDNA recombination. This silencing‐independent mechanism for suppressing rDNA recombination may therefore contribute to CR‐mediated lifespan extension.     

Interaction of Newly Synthesized Apolipoprotein B with Calnexin and Calreticulin Requires Glucose Trimming in the Endoplasmic Reticulum

Apolipoprotein B (ApoB) is the only protein component of the low density lipoproteins (LDL) in plasma. It is a glycoprotein with a molecular mass of about 550 kDa (4536 amino acids) containing 16 N-glycans. We have studied the interaction of ApoB with two lectin-like chaperones of the Endoplasmic Reticulum (ER)—Calnexin (CN) and Calreticulin (CR). Using a co-immunoprecipitation approach we observed that newly synthesized ApoB associates with CN and CR. The interaction was transient; within 30–60 min after synthesis bulk of newly formed ApoB dissociated. Using McA Rh7777 cells expressing an N-terminal fragment of ApoB we found that inhibition of glucosidases in the ER prevented the association of CN and CR to newly synthesized ApoB. The results showed that like for association with other glycoprotein substrates, trimming of glucose residues was essential for ApoB binding to CN and CR.