121 research outputs found
Phase diagram of aggregation of oppositely charged colloids in salty water
Aggregation of two oppositely charged colloids in salty water is studied. We
focus on the role of Coulomb interaction in strongly asymmetric systems in
which the charge and size of one colloid is much larger than the other one. In
the solution, each large colloid (macroion) attracts certain number of
oppositely charged small colloids (-ion) to form a complex. If the
concentration ratio of the two colloids is such that complexes are not strongly
charged, they condense in a macroscopic aggregate. As a result, the phase
diagram in a plane of concentrations of two colloids consists of an aggregation
domain sandwiched between two domains of stable solutions of complexes. The
aggregation domain has a central part of total aggregation and two wings
corresponding to partial aggregation. A quantitative theory of the phase
diagram in the presence of monovalent salt is developed. It is shown that as
the Debye-H\"{u}ckel screening radius decreases, the aggregation domain
grows, but the relative size of the partial aggregation domains becomes much
smaller. As an important application of the theory, we consider solutions of
long double-helix DNA with strongly charged positive spheres (artificial
chromatin). We also consider implications of our theory for in vitro
experiments with the natural chromatin. Finally, the effect of different shapes
of macroions on the phase diagram is discussed.Comment: 10 pages, 9 figures. The text is rewritten, but results are not
change
The Persistence Length of a Strongly Charged, Rod-like, Polyelectrolyte in the Presence of Salt
The persistence length of a single, intrinsically rigid polyelectrolyte
chain, above the Manning condensation threshold is investigated theoretically
in presence of added salt. Using a loop expansion method, the partition
function is consistently calculated, taking into account corrections to
mean-field theory. Within a mean-field approximation, the well-known results of
Odijk, Skolnick and Fixman are reproduced. Beyond mean-field, it is found that
density correlations between counterions and thermal fluctuations reduce the
stiffness of the chain, indicating an effective attraction between monomers for
highly charged chains and multivalent counterions. This attraction results in a
possible mechanical instability (collapse), alluding to the phenomenon of DNA
condensation. In addition, we find that more counterions condense on slightly
bent conformations of the chain than predicted by the Manning model for the
case of an infinite cylinder. Finally, our results are compared with previous
models and experiments.Comment: 13 pages, 2 ps figure
Conformational Instability of Rodlike Polyelectrolytes due to Counterion Fluctuations
The effective elasticity of highly charged stiff polyelectrolytes is studied
in the presence of counterions, with and without added salt. The rigid polymer
conformations may become unstable due to an effective attraction induced by
counterion density fluctuations. Instabilities at the longest, or intermediate
length scales may signal collapse to globule, or necklace states, respectively.
In the presence of added-salt, a generalized electrostatic persistence length
is obtained, which has a nontrivial dependence on the Debye screening length.
It is also found that the onset of conformational instability is a re-entrant
phenomenon as a function of polyelectrolyte length for the unscreened case, and
the Debye length or salt concentration for the screened case. This may be
relevant in understanding the experimentally observed re-entrant condensation
of DNA.Comment: 8 pages, 4 figure
Virological, immunological and pathological findings of transplacentally transmitted bluetongue virus serotype 1 in IFNAR1-blocked mice during early and mid gestation
© 2020, The Author(s). Transplacental transmission (TPT) of wild-type Indian BTV-1 had never been experimentally proved. This study was first time investigated TPT of Indian BTV-1 (isolated from aborted and stillborn goat fetal spleens). The sequential pathology, virological and immune cell kinetics (CD4+, CD8+ T-lymphocytes and NK cells in spleen and PBMCs), and apoptosis in IFNAR1-blocked pregnant mice during early (infected on 1 GD) and mid (infected on 8 GD) gestation have been studied. There was higher rate of TPT during mid stage (71.43%) than early (57.14%) stage. In early stage reduced implantation sites, early embryonic deaths, abortions, and necro-haemorrhagic lesions had observed. Mid stage, congenital defects and neurological lesions in foetuses like haemorrhages, diffuse cerebral edema, necrotizing encephalitis and decreased bone size (Alizarin red staining) were noticed. BTV-1 antigen was first time demonstrable in cells of mesometrium, decidua of embryos, placenta, uterus, ovary, and brain of foetuses by immunohistochemistry and quantified by real-time qRT-PCR. BTV-inoculated mice were seroconverted by 7 and 5 dpi, and reached peak levels by 15 and 9 dpi in early and mid gestation, respectively. CD4+ and CD8+ cells were significantly decreased (increased ratio) on 7 dpi but subsequently increased on 15 dpi in early gestation. In mid gestation, increased CD8+ cells (decreased ratio) were observed. Apoptotic cells in PBMCs and tissues increased during peak viral load. This first time TPT of wild-type Indian BTV-1 deserves to be reported for implementation of control strategies. This model will be very suitable for further research into mechanisms of TPT, overwintering, and vaccination strategies
Genome-Wide Differentiation of Various Melon Horticultural Groups for Use in GWAS for Fruit Firmness and Construction of a High Resolution Genetic Map
Ajuts: Funding support is provided by Gus R. Douglass Institute (Evans Allen Project to Nimmakayala) and USDA-NIFA (2010-02247 and 2012-02511).Melon (Cucumis melo L.) is a phenotypically diverse eudicot diploid (2n = 2x = 24) has climacteric and non-climacteric morphotypes and show wide variation for fruit firmness, an important trait for transportation and shelf life. We generated 13,789 SNP markers using genotyping-by-sequencing (GBS) and anchored them to chromosomes to understand genome-wide fixation indices (Fst) between various melon morphotypes and genomewide linkage disequilibrium (LD) decay. The FST between accessions of cantalupensis and inodorus was 0.23. The FST between cantalupensis and various agrestis accessions was in a range of 0.19-0.53 and between inodorus and agrestis accessions was in a range of 0.21-0.59 indicating sporadic to wide ranging introgression. The EM (Expectation Maximization) algorithm was used for estimation of 1436 haplotypes. Average genome-wide LD decay for the melon genome was noted to be 9.27 Kb. In the current research, we focused on the genome-wide divergence underlying diverse melon horticultural groups. A high-resolution genetic map with 7153 loci was constructed. Genome-wide segregation distortion and recombination rate across various chromosomes were characterized. Melon has climacteric and non-climacteric morphotypes and wide variation for fruit firmness, a very important trait for transportation and shelf life. Various levels of QTLs were identified with high to moderate stringency and linked to fruit firmness using both genome-wide association study (GWAS) and biparental mapping. Gene annotation revealed some of the SNPs are located in β-D-xylosidase, glyoxysomal malate synthase, chloroplastic anthranilate phosphoribosyltransferase, and histidine kinase, the genes that were previously characterized for fruit ripening and softening in other crops
Cancer-related ectopic expression of the bone-related transcription factor RUNX2 in non-osseous metastatic tumor cells is linked to cell proliferation and motility
10.1186/bcr2762Breast Cancer Research125-BCRR
Calculations of relative intensities of fragment ions in the MSMS spectra of a doubly charged penta-peptide
Pin1 and neurodegeneration: a new player for prion disorders?
Pin1 is a peptidyl-prolyl isomerase that catalyzes the cis/trans conversion of phosphorylated proteins at serine or threonine residues which precede a proline. The peptidyl-prolyl isomerization induces a conformational change of the proteins involved in cell signaling process. Pin1 dysregulation has been associated with some neurodegenerative disorders such as Alzheimer's disease, Parkinson's disease and Huntington's disease. Proline-directed phosphorylation is a common regulator of these pathologies and a recent work showed that it is also involved in prion disorders. In fact, prion protein phosphorylation at the Ser-43-Pro motif induces prion protein conversion into a disease-associated form. Furthermore, phosphorylation at Ser-43-Pro has been observed to increase in the cerebral spinal fluid of sporadic Creutzfeldt-Jakob Disease patients. These findings provide new insights into the pathogenesis of prion disorders, suggesting Pin1 as a potential new player in the disease. In this paper, we review the mechanisms underlying Pin1 involvement in the aforementioned neurodegenerative pathologies focusing on the potential role of Pin1 in prion disorders
The role of condensed tannins in ruminant animal production: advances, limitations and future directions
Disfavoring Macrocycle b Fragments by Constraining Torsional Freedom: The “Twisted” Case of QWFGLM b6
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