Microheterogeneity among carbohydrate structures at the cell surface may be important in recognition phenomena

Independently derived mutants of Chinese hamster ovary cells have been isolated and shown to exhibit a subtle glycosylation defect resulting in the premature termination of certain asparagine-linked carbohydrate moieties. This carbohydrate alteration is akin to the types of structural variation termed microheterogeneity and is thought not to affect the biological activities of glycoproteins that manifest the phenomenon. However, the carbohydrate change expressed by the mutants is stable and heritable, and ¹²⁵1-lectin-binding studies suggest that it profoundly alters their surface recognition properties. The mutation appears to affect a specific subpopulation of galactose residues in asparagine-linked carbohydrate of the type found associated with the G glycoprotein of vesicular stomatitis virus. The mutant cells also exhibit morphological changes in substratum culture.     

Small circular DNA complexes in eucaryotic cells

A small number of eucaryotic cells (100 to 1000 cells) were pressed by mica sheet; then the extruded contents were adsorbed on mica and processed for electron microscopy. In the absence of divalent cation, small polydisperse circular DNA molecules bound to proteins or membrane material were preferentially adsorbed. The small circular DNA complexes have been found in every eucaryotic cell, primary lymphoid tissue cells of bursa and thymus, primary cell lines of retina and liver, and established cultured cell lines of embryonal teratocarcinoma, F9 and PCC3, HeLa and 3T6. Size distribution of these DNA complexes varies, depending on the cell source. The circles less than 1 μm in contour length predominate in cultured cell lines and the larger ones in primary cell lines and cells in situ. Polydisperse covalently closed circular DNAs were recovered from thymus lymphocytes by the conventional dye-CsCl buoyant density method. Their size distribution was similar to that of the small circular DNA complexes detected by the mica-press-adsorption method. They are present in several tens to hundreds of copies per cell representing, at a maximum, 0.02% of the total cellular DNA. The possibility that small circular DNA complexes may result from gene rearrangement as well as from replicon “misfiring” (A. Varshavsky, 1981, Proc. Nat. Acad. Sci. USA 78, 3673–3677) are discussed.     

A new assay of X-prolyl dipeptidyl-aminopeptidase activity in human serum with glycylproline p-phenylazoanilide as substrate

Summary A new assay procedure for X-prolyl dipeptidyl-aminopeptidase activity in human serum was developed with glycylproline p-phenylazoanilide tosylate as substrate. p-Phenylazoaniline liberated by the enzyme reaction was measured photometrically at 493 nm after stopping the reaction with acid. This assay was simple and sensitive, and less than 50 l of human serum was required for the assay. Km value was 2.5 mm and the optimum pH was 8.7. After disc gel electrophoresis of human serum, the enzyme activity could be distinctly observed as a reddish band on the gel when the gel was incubated with this substrate.     

Trisomy 12p syndrome

Summary The first case of trisomy of probable 12p mosaicism originated de novo is presented. Comparison of the clinical findings of this patient with those of previously described cases of 12p trisomy derived from translocated chromosomes indicates that the symptoms of 12p trisomy are: (1) normal birth weight and physical development, (2) severe psychomotor retardation and generalized hypotonia, (3) peculiarly round face with prominent cheeks, hypertelorism, epicanthus, broad, flat nasal bridge, short nose with anteverted nostrils, large philtrum, broad, prominent lower lip, and (4) poly(syn)dactyly of feet.     

A new prenyltransferase from Micrococcuslysodeikticus

A new prenyltransferase which catalyzes the synthesis of geranyl pyrophosphate as the only product from dimethylallyl pyrophosphate and isopentenyl pyrophosphate has been separated from other known prenyltransferases from $\text{Micrococcus}\text{lysodeikticus}$. This enzyme fraction is also capable of synthesizing all-$\text{trans}$ geranylgeranyl pyrophosphate from farnesyl pyrophosphate and isopentenyl pyrophosphate though it lacks ability to synthesize farnesyl pyrophosphate.     

Triterpenoid saponins from Fatsia japonica

Five triterpenoid saponins isolated from the flowers, the mature fruits and the leaves of Fatsia japonica were identified as 3-O-[β-d-glucopyranosyl(1→4)-β-d-glucopyranosyl]-hederagenin (1), 3-O-[β-d-glucopyranosyl-(1→4)-α-l-arabinopyranosyl]-oleanolic acid (2), 3-O-[α-l-arabinopyranosyl]-hederagenin (3), 3-O-[β-d-glucopyranosyl]-hederagenin (4) and 3-O-[β-d-glucopyranosyl(1→4)-α-l-arabinopyranosyl]-hederagenin (5). The saponins 1 and 2 are new, naturally occurring, triterpenoid saponins. The distribution of the five saponins in three parts of the plant was investigated. Saponins 2, 3 and 5 were present in the flowers, saponins 1, 3, 4 and 5 were in the mature fruits and saponins 2, 3, 4 and 5 were in the leaves.     

A possible role of hydroxyproline-protein in oxygen-sensitive growth

Exposure of Avena coleoptile sections to 8% O₂ brought aboutrespiration decrease, resulting in a decrease of ATP production.The pH at the cell wall surface slightly rose in sections exposedto 8% O₂, while their growth was greatly accelerated. Moreover,this growth acceleration was observed even in sections treatedwith CCCP known to make membranes permeable for protons. Weconcluded that the growth acceleration with reduction of O₂concentration is probably not the result of secretion of H₊ions into cell wall compartments. Results of this study provided evidence to support the hypothesisthat there is an inverse relationship between hydroxyproline-proteinlevel and the ability of a cell to undergo rapid cell elongation.Total labeling of the cell wall fraction with ¹⁴C-proline wasunaffected by 8% O₂ treatment, although the radioactivitiesof hydroxyproline incorporated into this fraction during thetreatments fell to about 45% of the control. Moreover, the radioactivitiesof hydroxyproline incorporated into the SLS-insoluble cell wallfraction of sections exposed to 8% O₂ decreased to about 30%of the control. This decrease of hydroxyproline was also observedin sections treated with cycloheximide, which inhibits the secretionof H₊ ions into the cell wall compartment. Reduction of O₂ concentrationin the surrounding atmosphere affects not only the hydroxylationof peptidyl proline, but also the binding of hydroxyproline-protein(s)to cell wall polysaccharides, and the resulting decrease ofthe protein rigidly bound to them may induce cell elongation. (Received December 5, 1975; )     

Pummerer Rearrangement of Selenium-Containing Uracil Nucleosides

Abstract

Pummerer-type rearrangement of uracil nucleosides having a phenylseleno group in the 2′-, 3′-, and 5′-positions took place upon oxidation with MCPBA in CH₂Cl₂ followed by treatment with acid anhydrides to yield α-acyloxyselenides.     

Alterations of lymphocyte count and platelet volume precede cerebrovascular lesions in stroke-prone spontaneously hypertensive rats

Abstract

Background: Cerebral small vessel disease (CSVD) is associated with future stroke. Although pathological alteration in small vessels of patients with CSVD can be detected by neuroimaging, diagnosis of CSVD is delayed because it is an asymptomatic disease. The stroke-prone spontaneously hypertensive rat (SHRSP) show similar pathological features to human CSVD and develop stroke-related symptoms with advancing age.

Objective: We investigated the time course of haematological parameters in Wistar rats and SHRSP.

Material and Methods: Blood cells were analysed using an automated haematological analyser.

Results: SHRSP develop stroke-related symptoms including onset of neurological symptoms, decreased body weight and blood brain barrier leakage between 12 and 14?weeks of age. Lymphocyte counts were gradually decreased at 3?weeks before development of stoke-related symptoms and then were further decreased after the development of stroke-related symptoms. The both mean platelet volume and large platelet ratio gradually increased at 3?weeks before the development of stoke-related symptoms. However, although SHRSP showed more microcytic red cells than Wistar rats, the trajectories of change in erythrocyte-related parameters were similar between Wistar rats and SHRSP.

Conclusion: Our pilot study suggests that alterations of lymphocyte count and platelet volume predictive indicators for asymptomatic CSVD and symptomatic stroke in SHRSP.