Calcium addition at the Hubbard Brook Experimental Forest increases the capacity for stress tolerance and carbon capture in red spruce (Picea rubens) trees during the cold season

Red spruce (Picea rubens Sarg.) trees are uniquely vulnerable to foliar freezing injury during the cold season (fall and winter), but are also capable of photosynthetic activity if temperatures moderate. To evaluate the influence of calcium (Ca) addition on the physiology of red spruce during the cold season, we measured concentrations of foliar polyamines and free amino acids (putative stress-protection compounds), chlorophyll (a key photosystem component), and sapwood area (a proxy for foliar biomass), for trees in Ca-addition (CaSiO₃ added) and Ca-depleted (reference) watersheds at the Hubbard Brook Experimental Forest (NH, USA). Ca-addition increased concentrations of the amino acids alanine and γ-aminobutyric acid (GABA) and the polyamines putrescine (Put) and spermidine (Spd) in November, and Put in February relative to foliage from the reference watershed. Consistent with increased stress protection, foliage from the Ca-addition watershed had higher total chlorophyll and chlorophyll a concentrations in February than foliage from the reference watershed. In contrast, foliage from the reference watershed had significantly lower glutamic acid (Glu) and higher alanine (Ala) concentrations in February than foliage from the Ca-addition watershed. Imbalances in Ala:Glu have been attributed to cold sensitivity or damage in other species. In addition to concentration-based differences in foliar compounds, trees from the Ca-addition watershed had higher estimated levels of foliar biomass than trees from the reference watershed. Our findings suggest that Ca-addition increased the stress tolerance and productive capacity of red spruce foliage during the cold season, and resulted in greater crown mass compared to trees growing on untreated soils.     

A novel series of IKKβ inhibitors part II: description of a potent and pharmacologically active series of analogs

A novel series of (E)-1-((2-(1-methyl-1H-imidazol-5-yl) quinolin-4-yl) methylene) thiosemicarbazides was discovered as potent inhibitors of IKKβ. In this Letter we document our efforts at further optimization of this series, culminating in 2 with submicromolar potency in a HWB assay and efficacy in a CIA mouse model.     

Drosophila Nod protein binds preferentially to the plus ends of microtubules and promotes microtubule polymerization in vitro

Nod, a nonmotile kinesin-like protein, plays a critical role in segregating achiasmate chromosomes during female meiosis. In addition to localizing to oocyte chromosomes, we show that functional full-length Nod-GFP (Nod(FL)-GFP) localizes to the posterior pole of the oocyte at stages 9-10A, as does kinesin heavy chain (KHC), a plus end-directed motor. This posterior localization is abolished in grk mutants that no longer maintain the microtubule (MT) gradient in the oocyte. To test the hypothesis that Nod binds to the plus ends of MTs, we expressed and purified both full-length Nod (Nod(FL)) and a truncated form of Nod containing only the motor-like domain (Nod318) from Escherichia coli and assessed their interactions with MTs in vitro. Both Nod(FL) and Nod318 demonstrate preferential binding to the ends of the MTs, displaying a strong preference for binding to the plus ends. When Nod318-GFP:MT collision complexes were trapped by glutaraldehyde fixation, the preference for binding to plus ends versus minus ends was 17:1. Nod(FL) and Nod318 also promote MT polymerization in vitro in a time-dependent manner. The observation that Nod is preferentially localized to the plus ends of MTs and stimulates MT polymerization suggests a mechanism for its function.     

Homologous chromosome interactions in meiosis: diversity amidst conservation

Proper chromosome segregation is crucial for preventing fertility problems, birth defects and cancer. During mitotic cell divisions, sister chromatids separate from each other to opposite poles, resulting in two daughter cells that each have a complete copy of the genome. Meiosis poses a special problem in which homologous chromosomes must first pair and then separate at the first meiotic division before sister chromatids separate at the second meiotic division. So, chromosome interactions between homologues are a unique feature of meiosis and are essential for proper chromosome segregation. Pairing and locking together of homologous chromosomes involves recombination interactions in some cases, but not in others. Although all organisms must match and lock homologous chromosomes to maintain genome integrity throughout meiosis, recent results indicate that the underlying mechanisms vary in different organisms.     

Porcine endogenous retrovirus transmission characteristics of galactose alpha1-3 galactose-deficient pig cells

Galactose alpha1-3 galactose (Gal) trisaccharides are present on the surface of wild-type pig cells, as well as on viruses particles produced from such cells. The recognition of Gal sugars by natural anti-Gal antibodies (NAb) in human and Old World primate serum can cause the lysis of the particles via complement-dependent mechanisms and has therefore been proposed as an important antiviral mechanism. Recently, pigs have been generated that possess disrupted galactosyl-transferase (GGTA1) genes. The cells of these pigs do not express Gal sugars on their surface, i.e., are Gal null. Concerns have been raised that the risk of virus transmission from such pigs may be increased due to the absence of the Gal sugars. We investigated the sensitivity of porcine endogenous retrovirus (PERV) produced from Gal-null and Gal-positive pig cells to inactivation by purified NAb and human serum. PERV produced in Gal-null pig cells was resistant to inactivation by either NAb or human serum. In contrast, although Gal-positive PERV particles were sensitive to inactivation by NAb and human serum, they required markedly higher concentrations of NAb for inactivation compared to the Gal-positive cells from which they were produced. Complete inactivation of Gal-positive PERV particles was not achievable despite the use of high levels of NAb, indicating that NAb-mediated inactivation of cell-free PERV particles is an inefficient process.     

Differential effects of interleukin-7 and interleukin-15 on NK cell anti-human immunodeficiency virus activity

The ability of interleukin-7 (IL-7) and IL-15 to expand and/or augment effector cell functions may be of therapeutic benefit to human immunodeficiency virus (HIV)-infected patients. The functional effects of these cytokines on innate HIV-specific immunity and their impact on cells harboring HIV are unknown. We demonstrate that both IL-7 and IL-15 augment natural killer (NK) function by using cells (CD3(-) CD16(+) CD56(+)) from both HIV-positive and -negative donors. Whereas IL-7 enhances NK function through upregulation of Fas ligand, the effect of IL-15 is mediated through upregulation of tumor necrosis factor-related apoptosis-inducing ligand. The difference in these effector mechanisms is reflected by the ability of IL-15-treated but not IL-7-treated NK cells to reduce the burden of replication-competent HIV in autologous peripheral blood mononuclear cells (PBMC) (infectious units per million for control NK cells, 6.79; for IL-7-treated NK cells, 236.17; for IL-15-treated cells, 1.01; P = 0.01 versus control). In addition, the treatment of PBMC with IL-15-treated but not IL-7-treated NK cells causes undetectable HIV p24 (five of five cases), HIV RNA (five of five cases), or HIV DNA (three of five cases). These results support the concept of adjuvant immunotherapy of HIV infection with either IL-7 or IL-15 but suggest that the NK-mediated antiviral effect of IL-15 may be superior.     

Model identification for DNA sequence-structure relationships

We investigate the use of algebraic state-space models for the sequence dependent properties of DNA. By considering the DNA sequence as an input signal, rather than using an all atom physical model, computational efficiency is achieved. A challenge in deriving this type of model is obtaining its structure and estimating its parameters. Here we present two candidate model structures for the sequence dependent structural property Slide and a method of encoding the models so that a recursive least squares algorithm can be applied for parameter estimation. These models are based on the assumption that the value of Slide at a base-step is determined by the surrounding tetranucleotide sequence. The first model takes the four bases individually as inputs and has a median root mean square deviation of 0.90 A. The second model takes the four bases pairwise and has a median root mean square deviation of 0.88 A. These values indicate that the accuracy of these models is within the useful range for structure prediction. Performance is comparable to published predictions of a more physically derived model, at significantly less computational cost.     

Sometimes the result is not the answer: the truths and the lies that come from using the complementation test

It is standard genetic practice to determine whether or not two independently obtained mutants define the same or different genes by performing the complementation test. While the complementation test is highly effective and accurate in most cases, there are a number of instances in which the complementation test provides misleading answers, either as a result of the failure of two mutations that are located in different genes to complement each other or by exhibiting complementation between two mutations that lie within the same gene. We are primarily concerned here with those cases in which two mutations lie in different genes, but nonetheless fail to complement each other. This phenomenon is often referred to as second-site noncomplementation (SSNC). The discovery of SSNC led to a large number of screens designed to search for genes that encode interacting proteins. However, screens for dominant enhancer mutations of semidominant alleles of a given gene have proved far more effective at identifying interacting genes whose products interact physically or functionally with the initial gene of interest than have SSNC-based screens.     

Short-term plyometric training improves running economy in highly trained middle and long distance runners

Fifteen highly trained distance runners VO(2)max 71.1 +/- 6.0 ml.min(-1).kg(-1), mean +/- SD) were randomly assigned to a plyometric training (PLY; n = 7) or control (CON; n = 8) group. In addition to their normal training, the PLY group undertook 3 x 30 minutes PLY sessions per week for 9 weeks. Running economy (RE) was assessed during 3 x 4 minute treadmill runs (14, 16, and 18 km.h(-1)), followed by an incremental test to measure VO(2)max. Muscle power characteristics were assessed on a portable, unidirectional ground reaction force plate. Compared with CON, PLY improved RE at 18 km.h(-1) (4.1%, p = 0.02), but not at 14 or 16 km.h(-1). This was accompanied by trends for increased average power during a 5-jump plyometric test (15%, p = 0.11), a shorter time to reach maximal dynamic strength during a strength quality assessment test (14%, p = 0.09), and a lower VO(2)-speed slope (14%, p = 0.12) after 9 weeks of PLY. There were no significant differences in cardiorespiratory measures or VO(2)max as a result of PLY. In a group of highly-trained distance runners, 9 weeks of PLY improved RE, with likely mechanisms residing in the muscle, or alternatively by improving running mechanics.