Ograniczanie wyników

Czasopisma help
Autorzy help
Lata help
Preferencje help
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 35

Liczba wyników na stronie
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników

Wyniki wyszukiwania

help Sortuj według:

help Ogranicz wyniki do:
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
The present paper reports on the occurrence of Hemimysis anomala G.O. Sars, 1907 (Crustacea, Mysidacea) in the coastal waters of the Gulf of Gdańsk in the years 2002–2005.
Oznaczono wrażliwość 237 szczepów rodzaju Staphylococcus na naturalne i syntetyczne chelatory Fe3+. Poszukiwano związków między wrażliwością na chelator i przynależnością gatunkową szczepu oraz jego pochodzeniem.
The aim of this study was to evaluate the effect of boar semen storage in different short-term extenders (BTS, Kortowo-3, and M III) on the percentage of spermatozoa showing proapoptotic and necrotic changes. For the first time in this study, Annexin V isolated from swine placenta has been used to determine proapoptotic changes in stored boar spermatozoa. Die changes were determined using the IN Cell Analyzer 2000. A gradual decrease in motility was observed on successive days of storage. Spermatozoa incubated in the BTS extender were characterised by the highest average motility, which reached 75% on the 1st d and 39% on day 5. Motility of spermatozoa stored in BTS was significantly higher than those stored in Kortowo-3 and M III extenders after 5 d of storage. Diluted semen contained 1.5% to 2.8% spermatozoa with proapoptotic changes. The discussed process was intensified on the 3rd d of storage when the percentage of apoptotic spermatozoa was determined at 8.3% to 14.6%, and the content of dead spermatozoa exceeded 25%. The analysed extenders differed insignificantly in their ability to protect semen against proapoptotic changes during storage. From the methodological point of view, Hoechst 33258 could be used additionally to stain sperm cells regardless of their status.
 Affinity chromatography on Chelating Sepharose Fast Flow Gel-Zn2+ was used for fractionation of boar seminal plasma proteins. Approximately 30 % of total boar seminal plasma proteins showed affinity for zinc ions (ZnBP fraction). Native electrophoresis (PAGE) of ZnBP revealed six protein fractions which separated into 27 bands under denaturing conditions (SDS/PAGE). Two-dimensional electrophoresis (2D PAGE) showed 148 polypeptides with isoelectric points mostly in the basic and neutral pH range. The zinc-binding proteins comprise mainly 10-20 kDa polypeptides which are probably members of the spermadhesin family. ZnBP present in the incubation mixture of spermatozoa stored for 1 or 24 h at 4 °C allowed preservation of a higher percentage of cells exhibiting linear motility in comparison to a control sample stored in PBS. Presented results indicate that proteins binding Zn2+ ions have a shielding effect on the sperm plasma membrane and acrosome of spermatozoa, protecting these structures against consequences of cold shock.
An excessive generation of reactive oxygen species (ROS) in boar semen leads to a reduced motility and fertilizing ability of spermatozoa. Boar spermatozoa, because of a high content of polyunsaturated fatty acids (PUFAs) in their structure, are highly sensitive to lipid peroxidation (LPO). This process, induced by ROS generation, causes irreversible changes in the conformation and integrity of plasmalemma. The boar’s reproductive system includes a special antioxidant system consisting of enzymatic components and antioxidants of low molecular weight. The most active of antioxidant enzymes present in boar semen is superoxide dismutase (SOD). SOD transforms superoxide anion (O₂˙⁻) into hydrogen peroxide (H₂O₂). Because H₂O₂ can easily diffuse across the membranes, it is most harmful to boar spermatozoa. Given the low content of antioxidants of low molecular weight (e.g. L-gluthatione or L-ergothioneine) and the absence of catalase (CAT) activity in boar semen, there must be other mechanisms responsible for the scavenging of hydrogen peroxide and other ROS. This function is probably accomplished mainly by phospholipid hydroperoxide gluthatione peroxidase (PHGPx), enzymes of tioredoxin (TRX) and peroxiredoxin (PRDX) groups, as well as by paraoxonase type 1 and 2 (PON-1 and PON-2).
Niedobór żelaza wywołuje in vitro u enterokoków ekspresję nowych, regulowanych stężeniem żelaza białek. Ich obecność korelowała z wytwarzaniem sideroforów.
Acid phosphatase (AcP) is a commonly observed enzyme in animal semen. In this study, AcP in rainbow trout (Oncorhynchus mykiss) spermatozoa was partly purified and characterized. Extraction in 0.85% NaCl with 0.1% Triton X-100 enabled obtaining 95% of total AcP activity observed in sperm supernatant. Kinetic characteristics were described for the enzyme from sperm extract and for the partly purified enzyme following gel filtration. The optimum pH was 5.8 for unpurified and 5.6 for partly purified enzyme. The affinity of the substrates measured in the sperm extract for p-nitrophenylphosphate dissodium salt and b-glycerophosphate was Km = 1.5 × 10-3M and Km = 1.9 × 10-3M, respectively. The Km for partly purified enzyme was similar at 1.67 × 10-3M measured with p-nitrophenylphosphate dissodium salt. L-tartaric acid and ammonium molybdate were the inhibitors of AcP for unpurified and partly purified enzyme. SDS-PAGE electrophoresis revealed that AcP from rainbow trout had a molecular weight of about 41 kDa.
The phosphorylation of tyrosine protein residues in spermatozoa was dependent on the semen of individual boars at different stages of the cryopreservation technology. Sperm proteins in the fresh semen of a boar with poor semen freezability (boar K) exhibited a higher content of phosphotyrosine residues compared to boars with better semen freezability (boars F and J). In the semen samples extended in a Kortowo 3 extender (K3) and cooled at 16°C, there was a marked increase in protein phosphorylation in the sperm proteins of boars with good semen freezability. This was manifested in the appearance of phosphoproteins with molecular weights of 17, 32, 43, 52, 63 and 78 kDa. In the case of boar K, the cooled-storage of K3-extended semen at 5°C caused the extensive phosphorylation of sperm proteins, with molecular weights of 45, 65 i 100 kDa. A gradual reduction in sperm protein tyrosine phosphorylation was detected in the extender containing lipoprotein fraction isolated from ostrich egg yolk (LPFo) compared with the K3 extender, what has no protective substances. It might be suggested that seminal plasma acid phosphatases, especially the vesicular molecular form of acid phosphatase (PTAP), played a very important role in the regulation of tyrosine phosphorylation in boar sperm plasmalemma proteins. Differences were observed in the number of dephosphorylated proteins by different molecular forms of phosphatases. It was shown that phosphotyrosine residues in sperm proteins could be completely dephosphorylated by the vesicular PTAP. It seemed that only sperm phosphotyrosine proteins, with molecular weights of 17, 32, and 63 kDa, could be dephosphorylated by the epididymal molecular form of acid phosphatase.
Boar seminal vesicle protein tyrosine acid phosphatase (PTAP) and human prostatic acid phosphatase (PAP) show high affinity for protein phosphotyrosine residues. The physico-chemical and kinetic properties of the boar and human enzymes are different. The main objective of this study was to establish the nucleotide sequence of cDNA encoding boar PTAP and compare it with that of human PAP cDNA. Also, the amino-acid sequence of boar PTAP was compared with the sequence of human PAP. PTAP was isolated from boar seminal vesicle fluid and sequenced. cDNA to boar seminal vesicle RNA was synthesized, amplified by PCR, cloned in E. coli and sequenced. The obtained N-terminal amino-acid sequence of boar PTAP showed 92% identity with the N-terminal amino-acid sequence of human PAP. The determined sequence of a 354 bp nucleotide fragment (GenBank accession number: GQ184596) showed 90% identity with the corresponding sequence of human PAP. On the basis of this sequence a 118 amino acid fragment of boar PTAP was predicted. This fragment showed 89% identity with the corresponding fragment of human PAP and had a similar hydropathy profile. The compared sequences differ in terms of their isoelectric points and amino-acid composition. This may explain the differences in substrate specificity and inhibitor resistance of boar PTAP and human PAP.
Wśród zbioru 20 wytwarzających siderofory szczepów rodzaju Enterococcus izolowanych z różnych źródeł badano zdolność wzrostu w normalnej surowicy ludzkiej i surowicy ludzkiej wzbogaconej żelazem.
In Staphylococcus aureus B47 grown in iron-restricted medium, six new, iron-regulated proteins occurred in cytoplasmic membrane. Protein of 14kDa has bound two complexes of iron: Fe(III)-staphylobactin and Fe(III)-acinetoferrin. Complexes of Fe(III)-ferrichrome and Fe(III)-rhodotorulic acid were not bound to any of new membrane protein. Iron of Fe(III)-staphylobactin and Fe(III)-acinetoferrin complexes was transported into the cells.
The N-terminal amino acid sequence was analysed of 43 kDa polypeptide, component of the protein complex of PAF acetylhydrolase (PAF-AH) isolated from boar seminal plasma. Amino acid sequence of the 43 kDa did not show homology with the characteristic sequences of PAFAH isolated from other sources. However, 43 kDa showed a high homology with the characteristic sequences of IgG-binding proteins as well as with zona pellucida-binding adhesion proteins - zonadhesions. The results indicate that the isolated 43 kDa polypepfide belongs to the family of adhesion proteins, involved in the processes accompanying egg fertilization.
Pierwsza strona wyników Pięć stron wyników wstecz Poprzednia strona wyników Strona / 2 Następna strona wyników Pięć stron wyników wprzód Ostatnia strona wyników
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.