Respirational activity of Chlorella fusca monitored by in vivo P-31 NMR

Energy metabolism during dark respiration of the green alga Chlorella fusca was investigated by ³¹P NMR spectroscopy. The kinetics of the transition from anaerobic to aerobic conditions (and vice versa) was followed with a temporal resolution of 16 s. This transition is accompanied by a shift of the cytoplasmic pH from 6.8 to 7.4, while the vacuolar pH remains constant. Simultaneously, an increase in the concentration of nucleoside-triphosphates and a decrease in the concentration of cytoplasmic orthophosphate take place, as well as the formation of mobile polyphosphates. The concentration of ATP and P _i reach steady-state levels within 30 s. Upon the reverse transition, from aerobic to anaerobic conditions, steady-state concentrations are obtained only after 3 min.     

Optimizing clinical dosing of combination broadly neutralizing antibodies for HIV prevention

Broadly neutralizing antibodies (bNAbs) are promising agents to prevent HIV infection and achieve HIV remission without antiretroviral therapy (ART). As with ART, bNAb combinations are likely needed to cover HIV’s extensive diversity. Not all bNAbs are identical in terms of their breadth, potency, and in vivo longevity (half-life). Given these differences, it is important to optimally select the composition, or dose ratio, of combination bNAb therapies for future clinical studies. We developed a model that synthesizes 1) pharmacokinetics, 2) potency against a wide HIV diversity, 3) interaction models for how drugs work together, and 4) correlates that translate in vitro potency to clinical protection. We found optimization requires drug-specific balances between potency, longevity, and interaction type. As an example, tradeoffs between longevity and potency are shown by comparing a combination therapy to a bi-specific antibody (a single protein merging both bNAbs) that takes the better potency but the worse longevity of the two components. Then, we illustrate a realistic dose ratio optimization of a triple combination of VRC07, 3BNC117, and 10–1074 bNAbs. We apply protection estimates derived from both a non-human primate (NHP) challenge study meta-analysis and the human antibody mediated prevention (AMP) trials. In both cases, we find a 2:1:1 dose emphasizing VRC07 is nearly optimal. Our approach can be immediately applied to optimize the next generation of combination antibody prevention and cure studies.     

Structural studies of extracellular glucans of Streptococcus mutans by proton magnetic resonance

Proton magnetic resonance spectra at 100 MHz were obtained for water-soluble and water-insoluble glucans from 11 strains of Streptococcus mutans. The percentages of α-D-(1→6) and non-α-D-(1→6)-, namely, α-D-(1→3)-, linkages were calculated from the anomeric-proton resonances in the 4.7-4.8 and 5.0-5.1 p.p.m. range, respectively. The average content of α-D(1→6) linkages in the polymer fractions precipitating from solution during synthesis of the glucans was generally much lower than that of fractions remaining in solution. The frequent appearance of the α-D-(1→3) resonances as doublets in the spectra suggested neighboring-group effects among the possible α-D-(1→3) and α-D-(1→6) linkage-configurations. These effects were confirmed from 100-MHz spectra of products of a dextranase-degraded, water-insoluble glucan, and a 270-MHz spectrum of an undegraded glucan. It was thus possible to assign the doublet resonances to α-D-(1→3), homogeneous, heterogeneous, and branch configurations, although complete differentiation among proportions of each configuration in the glucan chains could not be achieved.     

Identification of domains of the v-crk oncogene product sufficient for association with phosphotyrosine-containing proteins.

The oncogene product of the avian sarcoma virus CT10, P47gag-crk, contains the SH2, SH2', and SH3 domains and binds proteins in a phosphotyrosine (ptyr)-dependent manner. In this study, we have determined the region of P47gag-crk essential for binding to ptyr-containing proteins. Mutant P47gag-crk proteins expressed in Escherichia coli that have the intact SH2 and SH2' regions retained the capacity to bind ptyr-containing proteins obtained from cells transformed by crk and src. The deletion of SH2 resulted in the loss of binding activity. Other mutants that have altered SH2 or SH2' bound few, if any, of the ptyr-containing proteins. Those mutants that bound ptyr-containing proteins associated with tyrosine kinase activity. We also found that polypeptides containing SH2, SH2', and SH3 of p60v-src and p60c-src associated with ptyr-containing proteins from crk-transformed cells. Thus, the SH2 and SH2' domains of P47gag-crk are responsible for their binding to ptyr-containing proteins.     

Linkage between low-density lipoprotein and igk light-chain genes in rabbits

The rabbit geneLpq, which codes for a low-density serum lipoprotein², is linked (34.6 ± 5.3 centimorgans) to the Ig kappa light-chain gene (Ab). There is no evidence thatLpq is linked to another gene,Prt, that was previously found to be linked to theAb gene. This suggests that the gene order for the three genes isPrt- Ab- Lpq. Abbreviations used in this paper Ig immunoglobulin - a the heavy-chain variable-region geneAa - b the kappa light-chain geneAb - q the low-density serum lipoprotein geneLpq