Hormones andCuscuta development: In vitro induction of haustoria by cytokinin and its inhibition by other hormones

Cytokinins induced haustoria formation in excised 10-mm segments ofCuscuta vine, the subapical 25-to-50-mm region being most responsive, producing a mean of 4–6 haustoria per segment. The order of effectiveness of cytokinins continuously applied (72 h) was 6-benzylaminopurine (BA) ges isopentenyladenine (iP) Gt zeatin (Z). Ribosides of BA and Z were as effective as the bases, whereas riboside of iP ([9R]iP) was half as effective as iP. Haustoria induction was influenced by weather and seasonal conditions at the time of vine collection; materials obtained on warm, sunny days responded better than those obtained on rainy, cloudy, or cool days. Haustoria were induced equally well all around the segment, and no thigmostimulus was needed for induction. p ]A 10-min pulse of 100 mgrM BA induced half as many haustoria as a 60-min pulse or continuous application of BA. White light inhibited haustoria induction elicited by a short (30-min) pulse of BA, whereas a longer (120-min) BA application overcame this light inhibition. Auxins (IAA or NAA, 1–10 mgrM), gibberellin (GA3, 1–10 mgrM), ethylene (as ethrel, 10–100 mgrM), and abscisic acid (ABA, 100 mgrM) were individually inhibitory (60–80%) with respect to haustoria induction when given continuously with 50 mgrM BA. A 60-min pulse of auxins (10 mgrM), GA3 (100 mgrM), or ethrel (10 mgrM), given at various time intervals during or after a 60-min pulse of 100 mgrM BA, showed that inhibition was maximal (70–95%) between 4 and 16 h of BA application and negligible (GA3) or much reduced (auxin, ethrel) at 20 h, indicating a ldquocommitmentrdquo to haustoria formation by this time.

Triacylglycerol synthesis in developing seeds of groundnut (Arachis hypogaea): Pathway and properties of enzymes of sn-Glycerol 3-phosphate formation

The enzymatic pathway for the synthesis of sn-glycerol 3-phosphate was investigated in developing groundnut seeds (Arachis hypogaea). Glycerol-3-phosphate dehydrogenase was not detected in this tissue but an active glycerokinase was demonstrated in the cytosolic fraction. It showed an optimum pH at 8.6 and positive cooperative interactions with both glycerol and ATP. Triosephosphate isomerase and glyceraldehyde-3-phosphate phosphatase were observed mainly in the cytosolic fraction while an active glyceraldehyde reductase was found mainly in the mitochondrial and microsomal fractions. The glyceraldehyde 3-phosphate phosphatase showed specificity and positive cooperativity with respect to glyceraldehyde 3-phosphate. The glyceraldehyde reductase was active toward glucose and fructose but not toward formaldehyde and showed absolute specificity toward NADPH. It is concluded that in the developing groundnut seed, sn-glycerol 3-phosphate is synthesized essentially by the pathway dihydroxyacetone phosphate ? glyceraldehyde 3-phosphate ?Pi glyceraldehyde ?NADPH glycerol ?ATP glycerol 3-phosphate. All the enyzmes of this pathway showed activity profiles commensurate with their participation in triacylglycerol synthesis which is maximal during the period 15�35 days after fertilization. Glycerokinase appears to be the rate-limiting enzyme in this pathway.

Functional Identification of Regulatory Elements within the Promoter Region of Platelet-Derived Growth Factor 2

Human platelet-derived growth factor (PDGF) is composed of two polypeptide chains, PDGF-1 and PDGF-2,the human homolog of the v-sis oncogene. Deregulation of PDGF-2 expression can confer a growth advantage to cells possessing the cognate receptor and, thus, may contribute to the malignant phenotype. We investigated the regulation of PDGF-2 mRNA expression during megakaryocytic differentiation of K562 cells. Induction by 12-O-tetradecanoylphorbol-13-acetate (TPA) led to a greater than 200-fold increase in PDGF-2 transcript levels in these cells. Induction was dependent on protein synthesis and was not enhanced by cycloheximide exposure.In our initial investigation of the PDGF-2 promoter, a minimal promoter region, which included sequences extending only 42 base pairs upstream of the TATA signal, was found to be as efficient as 4 kilobase pairs upstream of the TATA signal in driving expression of a reporter gene in uninduced K562 cells. We also functionally identified different regulatory sequence elements of the PDGF-2 promoter in TPA-induced K562 cells. One region acted as a transcriptional silencer, while another region was necessary for maximal activity of the promoter in megakaryoblasts. This region was shown to bind nuclear factors and was the target for trans-activation in normal and tumor cells. In one tumor cell line, which expressed high PDGF-2 mRNA levels, the presence of the positive regulatory region resulted in a 30-fold increase in promoter activity. However, the ability of the minimal PDGF-2 promoter to drive reporter gene expression in uninduced K562 cells and normal fibroblasts, which contained no detectable PDGF-2 transcripts, implies the existence of other negative control mechanisms beyond the regulation of promoter activity.

Effect of follicle-stimulating hormone and its antiserum on the activity of ornithine decarboxylase in the ovary of rat and hamster

The ability of FSH to stimulate the activity of ornithine decarboxylase (ODC) in the ovary of the immature rat and cycling hamster has been examined using specific antisera to gonadotropins. The stimulatory effect of FSH on ODC activity in the ovary of the immature rat was abolished when LH antiserum was administered along with FSH, while similar administration of FSH antiserum had no effect on LH action in stimulating ODC activity, thereby demonstrating the specificity of the LH effect. During the estrus cycle of the hamster, ODC activity in the ovary could be detected only on the evening of proestrus, the maximal activity seen at 1700 h being associated with both the Graafian follicles and the rest of the ovarian tissue. Neutralization of the proestrous FSH surge had no effect on the activity of ODC in either of these tissues, while similar administration of LH antiserum at 1300 h of proestrus completely inhibited the ODC activity in both large follicles and the rest of the ovarian tissue. Thus, the surge of LH, but not of FSH, appears to be responsible for regulating the ODC activity in the ovary of the cycling hamster.

A sufficient criterion for Rayleigh-Taylor instability of incompressible viscous three-layer flow

Using normal mode analysis Rayleigh-Taylor instability is investigated for three-layer viscous stratified incompressible steady flow, when the top 3rd and bottom 1st layers extend up to infinity, the middle layer has a small thickness δ. The wave Reynolds number in the middle layer is assumed to be sufficiently small. A dispersion relation (a seventh degree polynomial in wave frequency ω) valid up to the order of the maximal value of all possible Kj (j less-than-or-equals, slant 0, K is the wave number) in each coefficient of the polynomial is obtained. A sufficient condition for instability is found out for the first time, pursuing a medium wavelength analysis. It depends on ratios (α and β) of the coefficients of viscosity, the thickness of the middle layer δ, surface tension ratio T and wave number K. This is a new analytical criterion for Rayleigh-Taylor instability of three-layer fluids. It recovers the results of the corresponding problem for two-layer fluids. Among the results obtained, it is observed that taking the coefficients of viscosity of 2nd and 3rd layers same can inhibit the effect of surface tension completely. For large wave number K, the thickness of the middle layer should be correspondingly small to keep the domain of dependence of the threshold wave number Kc constant for fixed α, β and T.

1-Anilino-8-naphthalene sulfonate (ANS) binding to proteins revisited: Investigation of dye binding to molten globule states by electrospray ionization mass spectrometry

The binding of 1-anilino-8-naphthalene-sulfonic acid to globular proteins at acidic pH has been investigated by electrospray ionization mass spectrometry (ESIMS). Mass spectra of apomyoglobin recorded in the pH range 2−7 establish that maximal ANS binding is observed at pH 4.0. As many as seven distinct species may be observed in the gas phase which correspond to protein molecules containing one to six molecules of bound ANS. At neutral pH only a single molecule of ANS is bound. In the case of cytochrome c, maximal binding is observed at pH 4.0, with five molecules being bound. Binding is suppressed at neutral pH. In both cases ESIMS demonstrates maximal ANS binding at pH values where the proteins have been reported to exist in molten globule states. ANS binding is not observed for lysozyme, which has a tightly folded structure over the entire pH range. Reduction of disulfide bonds in lysozyme leads to the detection of ANS-bound species at neutral pH. Binding is suppressed at low pH due to complete unfolding of the reduced protein. The results suggest that ESIMS may provide a convenient method of probing the stoichiometry and distribution of dye complexes with molten protein globules

On a Ratio of Functions of Exponential Random Variables and Some Applications

Consider L independent and identically distributed exponential random variables (r.vs) X-1, X-2 ,..., X-L and positive scalars b(1), b(2) ,..., b(L). In this letter, we present the probability density function (pdf), cumulative distribution function and the Laplace transform of the pdf of the composite r.v Z = (Sigma(L)(j=1) X-j)(2) / (Sigma(L)(j=1) b(j)X(j)). We show that the r.v Z appears in various communication systems such as i) maximal ratio combining of signals received over multiple channels with mismatched noise variances, ii)M-ary phase-shift keying with spatial diversity and imperfect channel estimation, and iii) coded multi-carrier code-division multiple access reception affected by an unknown narrow-band interference, and the statistics of the r.v Z derived here enable us to carry out the performance analysis of such systems in closed-form.

Rapid burst of H2O2 by plant growth regulators increases intracellular Ca2+ amounts and modulates CD4(+) T cell activation

The identification of small molecules that affect T cell activation is an important area of research. Three molecules that regulate plant growth and differentiation, but not their structurally similar analogs, were identified to enhance primary mouse CD4(+) T cell activation in conjunction with soluble anti-CD3 stimulation: Indoleacetic acid (natural plant auxin), 1-Napthaleneacetic acid (synthetic plant auxin) and 2,4-Dichlorophenoxyacetic acid (synthetic plant auxin and herbicide). These effects are distinct in comparison to Curcumin, the well known phenolic immunomodulator, which lowers T cell activation. An investigation into the mechanisms of action of the three plant growth regulators revealed a rapid induction of reactive oxygen species (ROS), mainly comprising H2O2 . In addition, these three molecules synergize with soluble anti-CD3 signaling to enhance intracellular Ca2+ concentrations Ca2+](i), leading to greater T cell activation, e.g. induction of CD25 and IL-2. Enhanced production of TNF alpha and IFN gamma by CD4+ T cells is also observed upon plant growth regulator treatment with soluble anti-CD3. Interestingly, maximal IL-2 production and CD4(+) T cell cycle progression are observed upon activation with soluble anti-CD3 and phorbol 12-myristate 13-acetate (PMA), a phorbol ester. Additionally, stimulation with PMA and Ionomcyin (a Ca2+ ionophore), which activates T cells by circumventing the TCR, and plant growth regulators also demonstrated the role of the strength of signal (SOS): T cell cycle progression is enhanced with gentle activation conditions but decreased with strong activation conditions. This study demonstrates the direct effects of three plant growth regulators on CD4(+) T cell activation and cycling. (C) 2010 Elsevier B.V. All rights reserved.

DNA Polymerase4 from the Silk Glands of Bombyx mori

The silk gland of Bombyx mori is a terminally differentiated tissue in which DNA replication continues without cell or nuclear division during larval development. DNA polymerase-delta activity increases in the posterior and middle silk glands during the development period, reaching maximal levels in the middle of the fifth instar larvae. The enzyme has been purified to homogeneity by a series of column chromatographic and affinity purification steps. It is a multimer comprising of three heterogeneous subunits, M(r) 170,000, 70,000, and 42,000. An auxiliary protein from B. mori silk glands, analogous to the proliferating cell nuclear antigen, enhances the processivity of the enzyme and stimulates catalytic activity by 3-fold. This auxiliary protein has also been purified to homogeneity. It is a dimer comprised of a single type M(r) 40,000 subunit. Polymerase-delta possesses an intrinsic 3' --> 5' exonuclease activity which participates in proofreading by mismatch match repair during DNA synthesis and is devoid of any primase activity. DNA polymerase-delta activity could be further distinguished from polymerase-alpha from the same tissue based on its sensitivity to various inhibitors and polyclonal antibodies to the individual enzymes. Like DNA polymerase-alpha, polymerase-delta is also tightly associated with the nuclear matrix. The polymerase alpha-primase complex could be readily separated from polymerase-delta (exonuclease) in the purification protocol adopted. DNA polymerase-delta from B. mori silk glands resembles the mammalian delta-polymerases. Considering that both DNA polymerase-delta and -alpha are present in nearly equal amounts in this highly replicative tissue and their close association with the nuclear matrix, the involvement of both the enzymes in the chromosomal endoreplication process in B. mori is strongly implicated.

Hemiorchidectomy leads to dramatic and immediate alterations in pituitary follicle-stimulating hormone secretion and the functional activity of the remaining testis in the adult male bonnet monkey (Macaca radiata)

The aim of the present study was to examine the effect of hemiorchidectomy (HO) on serum FSH, LH, testosterone (T), and inhibin (INH) concentrations as well as on the testicular volume (TV) and on changes in the kinetics of germ cell turnovers in the remaining testis of adult male bonnet monkeys. Blood samples collected at 2200 h at various times before and after HO and testicular biopsies obtained at different periods were subjected to hormone analysis and DNA flow cytometry. Though serum T levels were lowered (p < 0.05) at 12 h after HO, T levels rapidly returned to intact control concentrations by Day 5. While serum LH remained unaltered, serum FSH increased markedly within 2 days of HO and remained significantly (p < 0.05) elevated over the next 90 days. Though serum INH showed a significant decrease (p < 0.05) by 15 min of HO, it returned to approximately 80% of intact levels within one week. The TV of the remaining testis showed maximal increment by Day 30 (p < 0.05) of HO. DNA flow cytometric analysis 24 days after HO showed increases (p < 0.05) in spermatogonia (2C) and primary spermatocytes (4C). These cell types by Day 45 had transformed to round (1C) and elongate (HC) (by 38%, p < 0.001) spermatids. Overall spermatogenesis (conversion of 2C to 1C and HC) showed significant enhancement at Days 110 and 175, suggesting that the spurt in spermatogenic activity is not confined to a single spermatogenic cycle.

Transformation formula for exponential sums involving fourier coefficients of modular forms

In 1984 Jutila [5] obtained a transformation formula for certain exponential sums involving the Fourier coefficients of a holomorphic cusp form for the full modular group SL(2, Z). With the help of the transformation formula he obtained good estimates for the distance between consecutive zeros on the critical line of the Dirichlet series associated with the cusp form and for the order of the Dirichlet series on the critical line, [7]. In this paper we follow Jutila to obtain a transformation formula for exponential sums involving the Fourier coefficients of either holomorphic cusp forms or certain Maass forms for congruence subgroups of SL(2, Z) and prove similar estimates for the corresponding Dirichlet series.

Boxicity and Poset Dimension

Let G be a simple, undirected, finite graph with vertex set V(G) and edge set E(C). A k-dimensional box is a Cartesian product of closed intervals a(1), b(1)] x a(2), b(2)] x ... x a(k), b(k)]. The boxicity of G, box(G) is the minimum integer k such that G can be represented as the intersection graph of k-dimensional boxes, i.e. each vertex is mapped to a k-dimensional box and two vertices are adjacent in G if and only if their corresponding boxes intersect. Let P = (S, P) be a poset where S is the ground set and P is a reflexive, anti-symmetric and transitive binary relation on S. The dimension of P, dim(P) is the minimum integer l such that P can be expressed as the intersection of t total orders. Let G(P) be the underlying comparability graph of P. It is a well-known fact that posets with the same underlying comparability graph have the same dimension. The first result of this paper links the dimension of a poset to the boxicity of its underlying comparability graph. In particular, we show that for any poset P, box(G(P))/(chi(G(P)) - 1) <= dim(P) <= 2box(G(P)), where chi(G(P)) is the chromatic number of G(P) and chi(G(P)) not equal 1. The second result of the paper relates the boxicity of a graph G with a natural partial order associated with its extended double cover, denoted as G(c). Let P-c be the natural height-2 poset associated with G(c) by making A the set of minimal elements and B the set of maximal elements. We show that box(G)/2 <= dim(P-c) <= 2box(G) + 4. These results have some immediate and significant consequences. The upper bound dim(P) <= 2box(G(P)) allows us to derive hitherto unknown upper bounds for poset dimension. In the other direction, using the already known bounds for partial order dimension we get the following: (I) The boxicity of any graph with maximum degree Delta is O(Delta log(2) Delta) which is an improvement over the best known upper bound of Delta(2) + 2. (2) There exist graphs with boxicity Omega(Delta log Delta). This disproves a conjecture that the boxicity of a graph is O(Delta). (3) There exists no polynomial-time algorithm to approximate the boxicity of a bipartite graph on n vertices with a factor of O(n(0.5-epsilon)) for any epsilon > 0, unless NP=ZPP.

Characterization of a 10- to 14-kilodalton protease-sensitive mycobacterium tuberculosis H37Ra antigen that stimulates human -yi T cells

gamma delta T-cell receptor-bearing T cells (gamma delta T cells) are readily activated by intracellular bacterial pathogens such as Mycobacterium tuberculosis. The bacterial antigens responsible for gamma delta T-cell activation remain poorly characterized. We have found that heat treatment of live M. tuberculosis bacilli released into the supernatant an antigen which stimulated human gamma delta T cells, gamma delta T-cell activation was measured by determining the increase in percentage of gamma delta T cells by flow cytometry in peripheral blood mononuclear cells stimulated with antigen and by proliferation of gamma delta T-cell lines with monocytes as antigen-presenting cells. Supernatant from heat-treated M. tuberculosis was fractionated by fast-performance liquid chromatography (FPLC) on a Superose 12 column. Maximal gamma delta T-cell activation was measured for a fraction of 10 to 14 kDa. Separation of the supernatant by preparative isoelectric focusing demonstrated peak activity at a pi of <4.0. On two-dimensional gel electrophoresis, the 10- to 14-kDa FPLC fraction contained at least seven distinct molecules, of which two had a pi of <4.5. Protease treatment reduced the bioactivity of the 10- to 14-kDa FPLC fraction for both resting and activated gamma delta T cells. Murine antibodies raised to the 10- to 14-kDa fraction reacted by enzyme-linked immunosorbent assay with antigens of 10 to 14 kDa in lysate of M. tuberculosis. In addition, gamma delta T cells proliferated in response to an antigen of 10 to 14 kDa present in M. tuberculosis lysate. gamma delta T-cell-stimulating antigen was not found in culture filtrate of M. tuberculosis but was associated,vith the bacterial pellet and lysate of M. tuberculosis. These results provide a preliminary characterization of a 10- to 14-kDa, cell-associated, heat-stable, low-pI protein antigen of M. tuberculosis which is a major stimulus for human gamma delta T cells.

DNA polymerase alpha-primase complex from the silk glands of the non-mulberry silkworm Philosamia ricini.

The DNA content in the silk glands of the non-mulberry silkworm Philosamia ricini increases continuously during the fourth and fifth instars of larval development indicating high levels of DNA replication in this terminally differentiated tissue. Concomitantly, the DNA polymerase alpha activity also increases in the middle and the posterior silk glands during development, reaching maximal levels in the middle of the fifth larval instar. A comparable level of DNA polymerase delta/epsilon was also observed in this highly replicative tissue. The DNA polymerase alpha-primase complex from the silk glands of P. ricini has been purified to homogeneity by conventional column chromatography as well as by immunoaffinity techniques. The molecular mass of the native enzyme is 560 kDa and the enzyme comprises six non-identical subunits. The identity of the enzyme as DNA polymerase alpha has been established by its sensitivity to inhibitors such as aphidicolin, N-ethylmaleimide, butylphenyl-dGTP, butylanilino-dATP and antibodies to polymerase alpha. The enzyme possesses primase activity capable of initiating DNA synthesis on single-stranded DNA templates. The tight association of polymerase and primase activities at a constant ratio of 6:1 is observed through all the purification steps. The 180 kDa subunit harbours the polymerase activity, while the primase activity is associated with the 45 kDa subunit.

Some results and approaches for reconstruction conjectures

Tutte (1979) proved that the disconnected spanning subgraphs of a graph can be reconstructed from its vertex deck. This result is used to prove that if we can reconstruct a set of connected graphs from the shuffled edge deck (SED) then the vertex reconstruction conjecture is true. It is proved that a set of connected graphs can be reconstructed from the SED when all the graphs in the set are claw-free or all are P-4-free. Such a problem is also solved for a large subclass of the class of chordal graphs. This subclass contains maximal outerplanar graphs. Finally, two new conjectures, which imply the edge reconstruction conjecture, are presented. Conjecture 1 demands a construction of a stronger k-edge hypomorphism (to be defined later) from the edge hypomorphism. It is well known that the Nash-Williams' theorem applies to a variety of structures. To prove Conjecture 2, we need to incorporate more graph theoretic information in the Nash-Williams' theorem.