Modeling of strain and filtration properties of a semi-finished leather product

Abstract

A study on deformation and filtration properties of a leather semi-finished product after chrome tanning are presented. The analytical dependences of compressive load on compressive (recovery) strain and moisture content of a leather semi-finished product are obtained. The empirical dependences of hydraulic gradient on filtration rates are determined for various compression ratios of the leather semi-finished product. It was revealed that with an increase in compressive load and moisture content of the leather semi-finished product, the compressive deformation increases. The shoulder section is subject to the greatest deformation, then the belly section and the least deformation is observed in the butt section. A linear relationship has been established between the hydraulic gradient and the rate of moisture filtration through the leather semi-finished product in the directions perpendicular and parallel to its surface.

Graphical abstract

Molecular diversity and association mapping of fiber quality traits in exotic G. hirsutum L. germplasm

The narrow genetic base of cultivated cotton germplasm is hindering the cotton productivity worldwide. Although potential genetic diversity exists in Gossypium genus, it is largely 'underutilized' due to photoperiodism and the lack of innovative tools to overcome such challenges. The application of linkage disequilibrium (LD)-based association mapping is an alternative powerful molecular tool to dissect and exploit the natural genetic diversity conserved within cotton germplasm collections, greatly accelerating still 'lagging' cotton marker-assisted selection (MAS) programs. However, the extent of genome-wide linkage disequilibrium (LD) has not been determined in cotton. We report the extent of genome-wide LD and association mapping of fiber quality traits by using a 95 core set of microsatellite markers in a total of 285 exotic Gossypium hirsutum accessions, comprising of 208 landrace stocks and 77 photoperiodic variety accessions. We demonstrated the existence of useful genetic diversity within exotic cotton germplasm. In this germplasm set, 11-12% of SSR loci pairs revealed a significant LD. At the significance threshold (r(2)>/=0.1), a genome-wide average of LD declines within the genetic distance at <10 cM in the landrace stocks germplasm and >30 cM in variety germplasm. Genome wide LD at r(2)>/=0.2 was reduced on average to approximately 1-2 cM in the landrace stock germplasm and 6-8 cM in variety germplasm, providing evidence of the potential for association mapping of agronomically important traits in cotton. We observed significant population structure and relatedness in assayed germplasm. Consequently, the application of the mixed liner model (MLM), considering both kinship (K) and population structure (Q) detected between 6% and 13% of SSR markers associated with the main fiber quality traits in cotton. Our results highlight for the first time the feasibility and potential of association mapping, with consideration of the population structure and stratification existing in cotton germplasm resources. The number of SSR markers associated with fiber quality traits in diverse cotton germplasm, which broadly covered many historical meiotic events, should be useful to effectively exploit potentially new genetic variation by using MAS programs.

Simple sequence repeat marker associated with a natural leaf defoliation trait in tetraploid cotton

Cotton (Gossypium hirsutum L.) leaf defoliation has a significant ecological and economical impact on cotton production. Thus the utilization of a natural leaf defoliation trait, which exists in wild diploid cotton species, in the development of tetraploid cultivated cotton will not only be cost effective, but will also facilitate production of very high-grade fiber. The primary goal of our research was to tag loci associated with natural leaf defoliation using microsatellite markers in Upland cotton. The F2 populations developed from reciprocal crosses between the two parental cotton lines--AN-Boyovut-2 (2n = 52), a late leaf defoliating type, and Listopad Beliy (2n = 52), a naturally early leaf defoliating type--demonstrated that the naturally early leaf defoliation trait has heritability values of 0.74 and 0.84 in the reciprocal F2 population. The observed phenotypic segregation difference in reciprocal crosses suggested a minor cytoplasmic effect in the phenotypic expression of the naturally early leaf defoliation trait. Results from the Kruskal-Wallis (KW) nonparametric test revealed that JESPR-13 (KW = 6.17), JESPR-153 (KW = 9.97), and JESPR-178 (KW = 13.45) Simple sequence repeat (SSR) markers are significantly associated with natural leaf defoliation in the mapping population having stable estimates at empirically obtained critical thresholds (P < .05-.0001). JESPR-178 revealed the highest estimates (P < .0001) for association with the natural leaf defoliation trait, exceeding maximum empirical threshold values. JESPR-178 was assigned to the short arm of chromosome 18, suggesting indirectly that genes associated with natural leaf defoliation might be located on this chromosome. This microsatellite marker may have the potential for use to introgress the naturally early leaf defoliation quantitative trait loci (QTL) from the donor line Listopad Beliy to commercial varieties of cotton through marker-assisted selection programs.

[Cytoplasmic thyroxine-binding protein: the role of RNA in the interactions between thyroxine receptor and cell nuclei]

The presence of 3H-orotic acid in the cytoplasmic receptor fraction isolated in our laboratory, the sensitivity of this fraction to treatment with RNAases accompanied by a shift of the absorption peak of the receptor preparation towards the long-wave region as well as the use of the absorption filter technique point to the existence of ternary thyroxine-thyroxine-binding protein-RNA complex in the cytoplasm. It was found that the cytoplasmic hormone-receptor complex of thyroxine is a genetically active form which can interact with the nuclei and modify the activity of chromatin. The role of RNA in these interactions is discussed.

[Interaction of hormone-receptor complexes from normal and tumorous tissues with DNA and their effect on the RNA polymerase activity of isolated nuclei]

A study was made of the interaction of the thyroxine hormone-receptor complexes (HRC) from hepatocytes and sarcoma M1 cells with DNA and the involvement of these complexes in the regulation of the RNA-polymerase activity of isolated hepatic cell nuclei. Unlike sarcoma HRC, rat liver HRC showed a weak interaction with DNA. Against a background of considerable stimulation of the incorporation of precursors in RNA under the influence of rat liver HRC (2.64 times), sarcoma HRC increased RNA synthesis in the system by 31.7% only to determine the RNA-polymerase activity of the nuclei. Proceeding from these results the authors have concluded that a thyroxine-binding receptor protein in malignant tissues is devoid of biological activity in the regulation of gene expression by the thyroid hormones, at least in the transcription phase.

[Effect of thyroid hormones on the nuclear-cytoplasmic transport of RNA]

The regulation of gene expression by hormones can be implemented at different levels: mRNA transcription, processing, transport from the nucleus into the cytoplasm, and translation. In the authors' earlier papers it was shown that the thyroxin hormone-receptor complex (HRC) increased chromatin matrix activity and induced new sites of transcription initiation. The present work was concerned with a study of the role of the thyroxin HRC in the regulation of the mechanism of 3H-RNA transport from the nucleus into the cytoplasm. An idea of the involvement of the HRC cytoplasmic thyroxin in RNA transport resulted from the detection in 30-40 S of RNP particles from rat liver nuclear proteins similar to the thyroxin cytoplasmic receptor by the antigen determinants. These data combined with others on the stimulation of 3H-RNA discharge from isolated nuclei under the influence of the thyroxin cytoplasmic HRC led to a conclusion that the thyroxin cytoplasmic HRC was involved in the regulation of gene expression by the thyroid hormones not only at the stage of transcription but also at the post-transcription stage, namely at the stage of RNA nuclear-cytoplasmic transport.

[The nature of thyroid hormone receptors. The role of serum thyroxine binding prealbumin in the realization of the hormonal effect]

Data from determination of molecular weight and competitive displacement suggest that T3 and T4 are bound to the same protein in chromatin. It was shown that the antigenic determinants of T3 and T4 for the chromatin-binding protein coincide with those for blood serum thyroxine-binding prealbumin (TBPA). It was found also that the binding either to T3 and T4 decreases proportionally to the amount of the TBPA removed from the subcellular fractions. It may thus be concluded that blood serum TBPA is responsible for the binding to T3 and T4 as well as for the realization of the hormonal response.

[The nature of thyroid hormone receptors. Intracellular transport and compartmentalization of chromatin receptors and thyroid hormones]

It is well established that in vivo administered labelled TBPA penetrates into liver, brain and lung cells, is translocated from cytosol into the nucleus and is accepted by chromatin without being affected by modifications touching upon the antigenic determinants of this protein. Electron microscopic autoradiography demonstrated that 125I-TBPA translocated from cytosol into the nucleus is localized on the border between hetero- and euchromatin. The data obtained may serve as an additional proof of the universal structure of intracellular thyroid hormone receptors and suggest that TBPA participate in manifestation of genetic effects of thyroid hormones.

[The nature of thyroid hormone receptors. Thyroxine- and triiodothyronine-binding proteins of mitochondria]

T4- and T3-binding proteins of rat liver were studied. It was found that the external mitochondrial membranes and matrix contain a protein whose electrophoretic mobility is similar to that of thyroxine-binding blood serum prealbumin (TBPA) and which binds either T4 or T3. This protein is precipitated by monospecific antibodies against TBPA. The internal mitochondrial membrane has two proteins able to bind thyroid hormones, one of which is localized in the cathode part of the gel and binds only T3, while the second one capable of binding T4 rather than T3 and possessing the electrophoretic mobility similar to that of TBPA. Radioimmunoprecipitation with monospecific antibodies against TBPA revealed that this protein also the antigenic determinants common with those of TBPA. The in vivo translocation of 125I-TBPA into submitochondrial fractions was studied. The analysis of densitograms of submitochondrial protein fraction showed that both TBPA and hormones are localized in the same protein fractions. Electron microscopic autoradiography demonstrated that 125I-TBPA enters the cytoplasm through the external membrane and is localized on the internal mitochondrial membrane and matrix.

[The nature of thyroid hormone receptors. Translocation of thyroid hormones through plasma membranes]

The in vivo translocation of thyroxine-binding blood serum prealbumin (TBPA) was studied. It was found that the TBPA-hormone complex penetrates-through the plasma membrane into the cytoplasm of target cells. Electron microscopic autoradiography revealed that blood serum TBPA is localized in ribosomes of target cells as well as in mitochondria, lipid droplets and Golgi complex. Negligible amounts of the translocated TBPA is localized in lysosomes of the cells insensitive to thyroid hormones (spleen macrophages). Study of T4- and T3-binding proteins from rat liver cytoplasm demonstrated that one of them has the antigenic determinants common with those of TBPA. It was shown autoimmunoradiographically that the structure of TBPA is not altered during its translocation.

[Nature of the intracellular thyroid hormone receptor]

Thyroxine-binding proteins were isolated and purified by means of affine chromatography from the blood serum, 105 000 g of cytosol supernatant, non-histone protein fractions of chromatin, extracted with 0.4 M KCl. Identity of their molecular weights and of end aminoacids was found. A comparative study of proteins above, using chromatoelectrophoresis, has shown identity of their primary structure. The data obtained indicate, that chromatin and cytosol contain universal, thyroxine-binding protein, which structure is identical with that of prealbumin thyroxine-binding protein. This protein is considered to be a receptor, realizing the control of genome expression by thyroid hormones.

[Regulation of genetic activity by thyroid hormones. II. Specificity of interaction of cytoplasmic thyroxine receptor isolated from human embryonal fibroblasts and HeLa cells with DNA]

The work concerns a new approach to evaluating the receptor and hormone-receptor complex specific interaction with DNA and revealing the cause of the absence of the hormone-receptor complex acceptation with HeLa cell chromosomes. It has been shown that hormone-receptor complexing should precede specific interaction with DNA. The purified receptor-thyroxin complex is saturatable and specifically competes with Hae III restrictase, protecting specific sites of DNA recognition from this enzyme. Specificity of the hormone-receptor complex interaction with DNA depends on the sequences surrounding Hae III restriction site. The HeLa cell hormone-receptor complex does not interact with the recognition site for the normal hormone-receptor complex.

[Regulation of genetic activity by thyroid hormones. Effect of purified cytoplasmic hormone-receptor complex on the chromatin template activity]

This paper continues a work series concerning the investigation of the functional activity of thyroxin receptor isolated from 105000 g fractions of the rat liver cytoplasm. Previously it was shown that the hormone-receptor complex stimulates the RNA-polymerase activity. In this work it was demonstrated that the complex changes the chromatine template activity, determined both under standard conditions and in the absence of transcription reinitiation. It appears that the hormone-receptor complex increases the number of the transcription initiation sites. Thyroxin cytoplasmatic receptor and/or the hormone, tested separately, exert no pronounced activating effect. It was concluded that the primary interaction between the hormone and specific receptor is necessary for participation in the transcription processes.

[Nuclear translocation and effect of cAMP-dependent protein kinase on transcription]

The influence of cAMP-dependent pig brain protein kinase and its subunits on transcription in vitro was studied. The increase in the template activity of chromatin isolated from the nuclei after treatment with the catalytic subunit was observed. The regulatory subunit of protein kinase was found to increase the number of binding sites for RNA polymerase on chromatin. The cAMP-dependent pig brain protein kinase was found to phosphorylate the sigma-factor of Escherichia coli RNA polymerase. This phosphorylation led to the increase of the RNA polymerase activity on phage lambda DNA. The nuclear translocation of the protein kinase and its subunits was shown to take place. In the cells with a low cAMP level (SV40 3T3) the transfer of the regulatory subunit to the nucleus was not detected. Only upon addition of cAMP and a subsequent formation of the cAMP-regulatory subunit complex, nuclear translocation was observed in these cells. The dependence of nuclear translocation of the cAMP-dependent protein kinase on cAMP level in the cell is proposed.

[Participation of thyroid hormones in the regulation of the genetic activity of normal and transformed human cells]

It is shown that 125J-thyroid hormones are localized on the structures of the interphasic nucleus and metaphasic chromosomes of cultured fibroblasts of 8--10-day human embryos. At the same time, the labelled thyroid hormones, though localizing in the interphasic nuclei of HeLa cells, are not accepted, unlike normal cells, by their metaphasic chromosomes. It is suggested that during transformation the acceptor ares of the HeLa cells genome lost their property to bind their own receptor complexes with thyroid hormones.