Histochemische Untersuchungen über den Involutionsmechanismus der Milchdrüse

Zusammenfassung Es wurden mit histochemischen Methoden Milchdrüsen von Meerschweinchen in physiologischer und durch Kastration während der Laktationsperiode hervorgerufener Involution untersucht. Nachgewiesen wurden alkalische und saure Phosphatase (APh und SPh), unspezifische Esterase, Sukzinodehydrase, SH-Gruppen, Nukleinsäuren und Lipide. — Die Aktivität der SPh nimmt während der Involution zu. Die Bedeutung dieses Enzyms für den Rückbildungsprozeß des Drüsengewebes wird diskutiert. — Das Vorkommen der APh-Aktivität in Drüsenendstücken im Involutionsstadium kann auf die Beteiligung dieses Enzyms an der Rückresorption der mit der Milch ausgeschiedenen Substanzen hinweisen. — Zwischen der Aktivität der unspezifischen Esterase und dem Gehalt sowie der Lokalisation von Lipiden besteht eine Abhängigkeit. — Es konnten keine Unterschiede in der Sukzinodehydraseaktivität und dem DNS-Gehalt aufgezeigt werden. — Die Verminderung von SH-Gruppen und RNS hängt mit dem Aufhören der Sekretionsproduktion durch die Zellen der Drüsenendstücke der Milchdrüsen zusammen.

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Histochemical studies on the involution mechanism of the mammary gland

Summary Histochemical methods were used to study mammary glands of guinea pigs in the course of physiologic involution and that induced by castration during lactation. Alkaline and acid phosphatases, unspecific esterase, succinic dehydrogenase, SH groups, nucleic acids and lipids were determined. Acid phosphatase activity was found to be increased in mammary glands, subject to involution. The participation of the enzyme in the involutionary process of the gland tissue is discussed. The distribution of alkaline phosphatase in the secretory sections of the gland during involution would suggest the participation of the enzyme in the reabsorption of the substance secreted with milk. A correlation existing between the activity of unspecific esterase, the level and distribution of lipids in the mammary gland could be established. No differences were detected in the activity of succinic dehydrogenase and DNA level. A decrease in SH groups and RNA content is related to cessation of milk secretion.

     

Biological role of endoreplication in the process of spermatogenesis inChara vulgaris L.

Summary During cell division in antheridial filaments ofChara vulgaris an increase in DNA content occurs in both shield cells and manubria within an antheridium, reaching 16C–64C and 8C–32C levels, respectively. Endoreplication ceases prior to the formation of spermatids and initiation of spermiogenesis, probably as a result of symplasmic isolation of the antheridium from the thallus. As the DNA content of the nuclei increases, the shield cells³H-leucine incorporation increases, and they grow intensively in the tangential plane. Translation decreases considerably after termination of shield cell growth. DNA content of mature manubria is half of that in shield cells, although their size is 10 times that of manubria. Translational activity of manubria also increases as DNA content rises and cells grow. However, during spermiogenesis, this activity remains at its maximum, which is associated with the secretory function of the manubria. Spermiogenesis is also accompanied by far-reaching ultrastructural changes within the manubrial cytoplasm.The level of endopolyploidy in both shield cells and manubria of antheridia formed in the spring is higher by one replication cycle, than in autumnal antheridia. AMO-1618, at a concentration of 10^–5M reduces the DNA content in the autumnal manubria. The higher the manubrial level of endopolyploidy in spermiogenesis, the greater their size, and the higher the translational activity and number of joined spermatids. The number of spermatozoids in the antheridium is also positively correlated with the internal volume of an antheridium, which is itself dependent on the endopolyploidy level of shield cells.The results obtained confirm the assumption that endoreplication favours the higher growth dynamics and potential translational activity, which occurs in the dynamic growth phase only in shield cells, while in manubria, i.e. cells producing substances necessary to spermatozoids development, it remains high until the end of spermiogenesis.     

Microbial transformation of azacarbazoles X: Regioselective hydroxylation of 5,11-dimethyl-5H-indolo [2,3-b]quinoline, a novel DNA topoisomerase II inhibitor, by Rhizopus arrhizus

Summary Microbial transformation of cytotoxic 5,11-dimethyl-5H-indolo[2,3-b]quinoline (a compound displaying antitumor activity and affecting the activity of calf thymus DNA topoisomerase II) was performed by the Rhizopus arrhizus strain and yielded a 9-hydroxy derivative. The metabolite obtained displayed a stronger cytotoxity against KB cells than the parent compound (ID₅₀=0.001 mol/mL), and stimulated also the formation of calf thymus topoisomerase II mediated pSP65 DNA cleavage in vitro at the concentration of 3 M. Being analogous to 9-hydroxyellipticine (which is an antitumor alkaloid), this novel indolo[2,3-b] quinoline derivative can be regarded as a novel potential antitumor agent.     

Isolation and characterization of extragenic mutations affecting the expression of the uroporphyrinogen decarboxylase gene (HEM12) in Sacharomyces cerevisiae

Uroporphyrinogen decarboxylase (Uro-d; EC 4.1.1.37), the fifth enzyme in the heme biosynthetic pathway, which catalyzes the sequential decarboxylation of uroporphyrinogen to coproporphyrinogen, is encoded by the HEM12 gene in Saccharomyces cerevisiae. The HEM12 gene is transcribed into a major short mRNA and a minor longer one, approximately 1.35 and 1.55 kb, respectively, in size, and that differ in the 5′ untranslated region. “Uroporphyric” mutants, which have no mutations in the HEM12 gene but accumulate uroporphyrinogen, a phenotype chracteristic of partial Uro-d deficiency, were investigated. Genetic analysis showed that the mutant phenotype depends on the combined action of two unlinked mutations, udt1 and either ipa1, ipa2, or ipa3. ipa1 is tightly linked to HEM12 The mutation udt1 apparently acts specifically on the HEM12 gene, and causes a six to tenfold decrease in the levels of the short HEM12 mRNA, in the β-galactosidase activity of a HEM12-lacZ fusion, in immunodetectable protein and enzyme activity. But heme synthesis is normal and porphyrin accumulation was modest. The mutations ipa1, ipa2, and ipa3 had no phenotype on their own, but they caused an increase in porphyrin accumulation in a udt1 background. This multiplicity of genetic factors leading to uroporphyric yeast cells closely resembles the situation in human porphyria cutanea tarda.     

Phytate dephosphorylation by free and immobilized cells ofSaccharomyces cerevisiae

Summary Saccharomyces cerevisiae in the form of baker's yeast, cells cultivated on a yeast extract-peptone-glucose medium, as well as cells immobilized in 18% (w/v) polyacrylamide gel showed the ability to hydrolyze 1.727 mM sodium phytate solution at 45°C, pH 4.6, in a stirred tank reactor. Seventy percent yield of dephosphorylation was observed after 2 h using a baker's yeast concentration of 5.8 g dry matter per 100 ml. Hydrolytic activity at 1.8–2.0 M Pi min^–1 was observed between 1st and 3rd h of the reaction in cells cultured 24 or 48 h. No inhibition by the substrate was found at sodium phytate concentrations of 0.587–1.727 mM. After 1.5 h of hydrolysis a single, well distinguished peak ofmyo-inositol-triphosphate was the main product found. By means of immobilization the stability of the biocatalyst was enhanced 3.3-fold and reached its half-life at 64 ninety-minute runs.     

Phytochemistry and pharmacology of sea buckthorn (Elaeagnus rhamnoides; syn. Hippophae rhamnoides): progress from 2010 to 2021

Phytochemistry Reviews - Sea buckthorn (Elaeagnus rhamnoides; syn. Hippophae rhamnoides) is a thorny shrub or a small tree belonging to the Elaeagnaceae family, native to Eurasia. Sea buckthorn...     

The role of acid phosphatase activity during enzymic dephosphorylation of phytates byAspergillus niger phytase

Acid phosphatase present in preparations ofAspergillus niger phytase accelerated dephosphorylation of sodium phytate. Its influence on the reaction rate and distribution ofmyo-inositol phosphates was most apparent at low pH value (2.5) and when acid-hydrolysed substrate was de-esterified enzymatically. With partly purified phytase, the predominant inositol form was tetraphosphate but a preparation having acid phosphatase activity caused an even distribution of lower inositol phosphates after a few hours.     

Immunological properties of low molecular-weight proteins binding heavy metals in rat kidney and liver

Two homogenous fractions of hepatic metallothioneins ((Cd,Zn) MT-1 and (Cd,Zn) MT-2) and renal metal binding proteins ((Bi,Cu) BP-1 and (Bi,Cu) BP-2) were isolated from rats exposed to heavy metals and specific antisera to them were produced in rabbits.These antisera were tested by immunodiffusion and immunoelectrophoresis for their ability to bind different fractions of hepatic Cd,Zn -metallothionein and renal (Bi,Cu)-, (Hg,Cu)- and (Cd,Cu)-binding proteins. It was found that anti (Bi,Cu) BP antisera did not cross-react with hepatic (Cd,Zn) MT-1 and (Cd,Zn) MT-2. Strong immunological cross-reactions were detected between anti (Bi,Cu) BP antisera and individual forms of (Cd,Cu)-, (Hg,Cu)- and (Bi,Cu)-binding proteins isolated from rat kidneys.