Cyclical changes in the fine structure of bovine endometrial gland cells

Summary Cyclical changes in bovine endometrial gland cells were investigated in six heifers, three at estrus and three at day twelve of the estrous cycle in the luteal phase. The epithelium is generally low at estrus but high in the luteal phase. There are ciliated and non-ciliated cells. The ciliated cells are fewer and lighter and show inconspicuous cyclical changes.The secretory cells show more prominent changes. At estrus, their free border is flat with short microvilli. The conspicuous rough-surfaced endoplasmic reticulum may synthesize protein for later secretion. The Golgi complex seems inactive. The high number of cytosegresomes and dense bodies might express cell regression caused by endocrine changes.In the luteal phase, the cells are lighter with long microvilli. The Golgi apparatus shows vacuoles and immature secretory droplets. Secretory vacuoles with light contents occur in the apical cytoplasm. Some of them appear to discharge their contents into the lumen. This is interpreted as evidence of merocrine secretion. Accumulations of tubular, smooth-surfaced endoplasmic reticulum, masses of glycogen granules, and several fat droplets are present.Some lymphocytes and degranulated granulocytes are seen near the basement membrane, more frequently at estrus.Financial support for this study was received from Anslaget för främjande av medicinsk forskning vid Veterinärhögskolan.The authors express their gratitude to Prof. A. Bane and Dr. J.-E. E. Ringmar, Department of Obstetrics and Gynecology, for their help with the selection and clinical control of the animals and for keeping them in good condition.Post doctoral fellow, No. 43-KO-52 (1968) from the Educational Ministry of Japan.     

Purification to homogeneity of human placental acid sphingomyelinase

Acid sphingomyelinase was purified to homogeneity from human placenta in the presence of a dialyzable detergent, n-octyl-beta-D-glucopyranoside. The major steps in the procedure included column chromatographies with Con A-Sepharose, sphingosylphosphorylcholine-Sepharose 4B, hexyl-agarose, and Mono P. The purified enzyme with pI 7.4 had a specific activity of approx 170,000 units/mg protein with a yield of 3.6%. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed a single protein band of Mr 62,000. Gel filtration with a Superose 12 column gave a single peak, and the enzyme in the presence 50 mM n-octyl-beta-D-glucopyranoside was of Mr 123,000, indicating that the native enzyme occurs in a dimeric form. The optimal pH was 5.5 with both sphingomyelin and an artificial substrate, 2-N-hexadecanoylamino-4-nitrophenylphosphorylcholine. The Km values were 55 microM with sphingomyelin and 340 microM with the artificial substrate. The enzyme activity was not affected by Mg2+ (1-5 mM), confirming that the enzyme is acid sphingomyelinase. The enzyme was stable at -80 degrees C for more than 4 months. In addition to the enzyme with pI 7.4, the Mono P chromatofocusing gave two peaks (pI 7.0 and 6.7) possessing the enzymatic activity.     

Studies on the cell-cycle dependency of the actions of insulin-like growth factor-I in Balb/c 3T3 cells

The present study was conducted to determine the cell-cycle dependency of various actions of IGF-I in Balb/c 3T3 cells. When autophosphorylation of the IGF-I receptor was determined in [32P]-labelled cells, IGF-I increased radioactivity in a 100 K-Da phosphoprotein, presumably beta-subunit of the IGF-I receptor, both in quiescent and in primed competent cells. Likewise, IGF-I stimulated uptake of [3H]deoxyglucose independent of the cell cycle. In contrast, IGF-I increased calcium entry, radioactivity in [3H]diacylglycerol, and [3H]thymidine incorporation in primed competent cells while these reactions were not induced by IGF-I in quiescent cells. The latter three reactions were attenuated when cells were pretreated with pertussis toxin. These results indicate that some, but not all, of the actions of IGF-I are dependent on the cell cycle in Balb/c 3T3 cells. They also suggest that a pertussis-toxin-sensitive G protein may be involved in the cell-cycle-dependent actions of IGF-I.     

Synthesis of polypeptides by microwave heating I. Formation of polypeptides during repeated hydration-dehydration cycles and their characterization

Summary Amino acid amides effectively reacted to produce polypeptides in response to microwave heating during repeated hydration-dehydration cycles. The polypeptides, formed from a mixture of glycinamide, alaninamide, valinamide, and aspartic acid -amide, had molecular weights ranging from 1000 to 4000 daltons. Amino acids were incorporated into the polypeptides in proportion to the starting concentrations, with the exception of glycine whose incorporation was 1.5 times higher than that of the other amino acids. The polypeptides had some definite secondary structure, such as -helix and -sheet, in aqueous solution. This reaction provides not only a convenient method for abiotic peptide formation but also a convenient method for the chemical synthesis of peptides.