The Drosophila mus 308 gene product, implicated in tolerance of DNA interstrand crosslinks, is a nuclear protein found in both ovaries and embryos

mus 308 designates one of over 30 mutagen sensitivity loci found in Drosophila. It is predicted to code for a 229-kDa polypeptide. Published sequence analyses of others indicate that this polypeptide would have helicase motifs near its N-terminus, and similarities to bacterial DNA polymerase I-like enzymes near its C-terminus. In our studies, two different and highly specific antibodies were prepared and used for identification as well as characterization of the mus 308 gene product. Western blot analyses reveal a single reactive polypeptide in both ovaries and embryos as well as in two Drosophila embryo tissue culture cell lines; it is nearly absent in homozygous mus 308 mutants. This polypeptide is about 229 kDa in size, and indirect immunofluorescence shows that the mus 308 gene product localizes throughout nuclei in wild-type cells but appears to be absent in a mus 308 mutant. Immunoblot analyses throughout development suggest greatest abundance at the end of embryogenesis, immediately before hatching of first instar larvae. They also showed a smaller ( approximately 100 kDa) antigenically and genetically related polypeptide found only in adult males. Immunoprecipitation, a highly effective method of specific purification, suggests that the mus 308 protein has DNA polymerase activity that is NEM-sensitive but largely aphidicolin-resistant. In addition, the immunoprecipitated material has DNA-dependent ATPase but lacks detectable helicase.     

OX40 signals during priming on dendritic cells inhibit CD4 T cell proliferation: IL-4 switches off OX40 signals enabling rapid proliferation of Th2 effectors

In this study we examined the role and regulation of OX40 signals during CD4 T cell priming on dendritic cells (DCs). Contrary to expectation, OX40-deficient cells proliferated more rapidly than their normal counterparts, particularly when stimulated with peptide in the absence of added cytokines. This proliferative advantage was not apparent for Th2-differentiated cells. When the reasons for this were investigated, we found that the cytokine IL-4 specifically down-regulated expression of OX40 ligand on T, B, and DCs, but not on the CD4(+)CD3(-) cells linked with selection of Th2 cells into the memory compartment. OX40 ligand expression was also down-regulated on rapidly proliferating Th1 effectors. These data are compatible with OX40 signals acting during priming as a check on naive T cell proliferation while T cells integrate additional DC signals. This would serve to limit inappropriate T cell responses. In contrast, OX40 signals from CD4(+)CD3(-) cells located in the outer T zone select proliferating Th2 effectors into the memory T cell pool.     

Mice deficient in OX40 and CD30 signals lack memory antibody responses because of deficient CD4 T cell memory

Recently, we reported that a CD4(+)CD3(-)CD11c(-) accessory cell provided OX40-dependent survival signals to follicular T cells. These accessory cells express both OX40 ligand and CD30 ligand, and the receptors, OX40 and CD30, are both expressed on Th2-primed CD4 T cells. OX40 and CD30 signals share common signaling pathways, suggesting that CD30 signals might substantially compensate in OX40-deficient mice. In this report we have dissected the signaling roles of CD30 alone and in combination with OX40. CD30-deficient mice showed an impaired capacity to sustain follicular germinal center responses, and recall memory Ab responses were substantially reduced. Deficiencies in OX40 and CD30 signals were additive; secondary Ab responses were ablated in double-deficient mice. Although the initial proliferation of OX40/CD30 double-knockout OTII transgenic T cells was comparable to that of their normal counterparts, they failed to survive in vivo, and this was associated with reduced T cell numbers associated with CD4(+)CD3(-) cells in B follicles. Finally, we show that OX40/CD30 double-knockout OTII transgenic T cells fail to survive compared with normal T cells when cocultured with CD4(+)CD3(-) cells in vitro.     

Postrelease dive ability in rehabilitated harbor seals

The efficacy of seal rehabilitation is examined in a postrelease study of dive ability in harbor seal pups (Phoca vitulina) in the Wash, United Kingdom. Six rehabilitated seals were fitted with Sea Mammal Research Unit (SMRU) Argos Satellite Relay Data Logger tags and their individual dive behavior was monitored for an average of 122 d. The upper 90 percentile edge of dive behavior (dive duration [DD₉₀] and percentage of time at‐sea spent in a dive [PD₉₀]), in 7 d bins, was used as a proxy for physiological dive ability. The results are compared with data from five wild adult harbor seals. There was no statistically significant difference between (1) the mean track duration of rehabilitated seals (126.20 ± 27.48 [SD] d) and adult seals (150.2 ± 24.62 d) (P= 0.108), indicating no evidence that short‐term survival was less in the rehabilitated group; (2) the mean mass‐scaled DD₉₀ of rehabilitated seals (3.95 ± 0.37 min) and adult seals (4.09 ± 0.55 min) (P= 0.632); and (3) the mean PD₉₀ of rehabilitated seals (81.62 ± 1.21%) and adult seals (81.48 ± 3.93%) (P= 0.943). These three results all suggest the success of the rehabilitation program in terms of short‐term survival and dive ability.     

Norepinephrine: A Neuromodulator That Boosts the Function of Multiple Cell Types to Optimize CNS Performance

Norepinephrine (NE) is a neuromodulator that in multiple ways regulates the activity of neuronal and non-neuronal cells. NE participates in the rapid modulation of cortical circuits and cellular energy metabolism, and on a slower time scale in neuroplasticity and inflammation. Of the multiple sources of NE in the brain, the locus coeruleus (LC) plays a major role in noradrenergic signaling. Processes from the LC primarily release NE over widespread brain regions via non-junctional varicosities. We here review the actions of NE in astrocytes, microglial cells, and neurons based on the idea that the overarching effect of signaling from the LC is to maximize brain power, which is accomplished via an orchestrated cellular response involving most, if not all cell types in CNS.     

A preliminary biomechanical study of cyclic preconditioning effects on canine cadaveric whole femurs

Biomechanical preconditioning of biological specimens by cyclic loading is routinely done presumably to stabilize properties prior to the main phase of a study. However, no prior studies have actually measured these effects for whole bone of any kind. The aim of this study, therefore, was to quantify these effects for whole bones. Fourteen matched pairs of fresh-frozen intact cadaveric canine femurs were sinusoidally loaded in 4-point bending from 50?N to 300?N at 1?Hz for 25 cycles. All femurs were tested in both anteroposterior (AP) and mediolateral (ML) bending planes. Bending stiffness (i.e., slope of the force-vs-displacement curve) and linearity R(2) (i.e., coefficient of determination) of each loading cycle were measured and compared statistically to determine the effect of limb side, cycle number, and bending plane. Stiffnesses rose from 809.7 to 867.7?N/mm (AP, left), 847.3 to 915.6?N/mm (AP, right), 829.2 to 892.5?N/mm (AP, combined), 538.7 to 580.4?N/mm (ML, left), 568.9 to 613.8?N/mm (ML, right), and 553.8 to 597.1?N/mm (ML, combined). Linearity R(2) rose from 0.96 to 0.99 (AP, left), 0.97 to 0.99 (AP, right), 0.96 to 0.99 (AP, combined), 0.95 to 0.98 (ML, left), 0.94 to 0.98 (ML, right), and 0.95 to 0.98 (ML, combined). Stiffness and linearity R(2) versus cycle number were well-described by exponential curves whose values leveled off, respectively, starting at 12 and 5 cycles. For stiffness, there were no statistical differences for left versus right femurs (p?=?0.166), but there were effects due to cycle number (p?相似文献   

Ss-bCNGa: a unique member of the bacterial cyclic nucleotide gated (bCNG) channel family that gates in response to mechanical tension

Bacterial cyclic nucleotide gated (bCNG) channels are generally a nonmechanosensitive subset of the mechanosensitive channel of small conductance (MscS) superfamily. bCNG channels are composed of an MscS channel domain, a linking domain, and a cyclic nucleotide binding domain. Among bCNG channels, the channel domain of Ss-bCNGa, a bCNG channel from Synechocystis sp. PCC 6803, is most identical to Escherichia coli (Ec) MscS. This channel also exhibits limited mechanosensation in response to osmotic downshock assays, making it the only known full-length bCNG channel to respond to hypoosmotic stress. Here, we compare and contrast the ability of Ss-bCNGa to gate in response to mechanical tension with Se-bCNG, a nonmechanosensitive bCNG channel, and Ec-MscS, a prototypical mechanosensitive channel. Compared with Ec-MscS, Ss-bCNGa only exhibits limited mechanosensation, which is most likely a result of the inability of Ss-bCNGa to form the strong lipid contacts needed for significant function. Unlike Ec-MscS, Ss-bCNGa displays a mechanical response that increases with protein expression level, which may result from channel clustering driven by interchannel cation?C?? interactions.     

Delta-opioid augments cardiac contraction through β-adrenergic and CGRP-receptor co-signaling

Cardiac epinephrine and calcitonin gene-related peptide (CGRP) are produced by intrinsic cardiac adrenergic cells (ICA cells) residing in human and animal hearts. ICA cells are neuroparicine cells expressing δ-opioid receptors (DOR). We hypothesized that δ-opioid stimulation of ICA cells enhances epinephrine and CGRP release, which results in the augmentation of heart contraction. Rats were injected with DOR-agonist DPDPE (100 μg/kg) with or without 10-min pretreatment with either β-adrenergic receptor (β-AR) blocker propranolol (2mg/kg) or CGRP-receptor (CGRPR) blocker CGRP(8-37) (300 μg/kg), or their combination. Hemodynamics were monitored with echocardiogram and systolic blood pressure (SBP) was monitored via a tail arterial catheter. Changes in left ventricular fraction-shortening (LVFS) and heart rate (HR) were observed at 5-min after DPDPE infusion. At 5-min DPDPE induced a 36 ± 18% (p<0.001) increase of the LVFS, which continues to increase to 51 ± 24% (p<0.0001) by 10 min, and 68 ± 19% (p<0.001) by 20 min. The increase in LVFS was accompanied by the decrease of HR by 9±5% (p<0.01) by 5 min and 11 ± 6% (p<0.001) by 15 min post DPDPE infusion. This magnitude of HR reduction was observed for the remainder of the 20 min. Despite the HR-reduction, cardiac output was increased by 17 ± 8% (p<0.05) and 28±5% (p<0.001) by 5- and 20-min post DPDPE administration, respectively. There was a modest (9 ± 9%, p=0.03) decrease in SBP that was not apparent until 20 min post DPDPE infusion. The positive inotropism of DPDPE was abrogated in animals pretreated with propranolol, CGRP(8-37), or combined propranolol+CGRP(8-37). Furthermore, in whole animal and cardiomyocyte cell culture preparations, DPDPE induced myocardial protein-kinase A (PKA) activation which was abrogated in the animals pretreated with propranolol+CGRP(8-37). DOR agonists augment myocardial contraction through enhanced β-AR and CGRPR co-signaling.     

Discovery of a series of 2-(1H-pyrazol-1-yl)pyridines as ALK5 inhibitors with potential utility in the prevention of dermal scarring

A series of 2-(1H-pyrazol-1-yl)pyridines are described as inhibitors of ALK5 (TGFβ receptor I kinase). Modeling compounds in the ALK5 kinase domain enabled some optimization of potency via substitutions on the pyrazole core. One of these compounds PF-03671148 gave a dose dependent reduction in TGFβ induced fibrotic gene expression in human fibroblasts. A similar reduction in fibrotic gene expression was observed when PF-03671148 was applied topically in a rat wound repair model. Thus these compounds have potential utility for the prevention of dermal scarring.