Method of separating mouse platelets by discontinuous sucrose-gradient centrifugation

A discontinuous sucrose gradient was employed in the separation of mouse blood platelets using a modified Booyse method. The platelets of male CD-1 mice aged 8 to 12 weeks were divided into five distinct populations (A, B, C, D & E). Distribution of light to heavy platelets patterns in 10 normal CD-1 mice was demonstrable at; A (S.G. 1.188), as 14.8 +/- 5.6%; B (S.G. 1.199), 44.0 +/- 4.6%; C (S.G. 1.207), 24.1 +/- 3.4%; D (S.G. 1.214), 13.0 +/- 3.6%; and E (S.G. 1.221), 4.0 +/- 1.5%.     

Immunohistochemical colocalization of glucagon,serotonin, and aromatic L-amino acid decarboxylase in islet A cells of chicken pancreas

Summary The identity of monoamine-emitted, formaldehyde-induced fluorescence in some pancreatic islet cells was studied in pancreatic tissue of male chickens by fluorescence and immunohistochemistry either on the same tissue section or on serial tissue sections. Pancreatic islet cells emitting intense formaldehyde-induced fluorescence also react immunohistochemically with antisera directed against glucagon, serotonin and aromatic L-amino acid decarboxylase. These results show that chicken pancreatic islet A cells contain glucagon, serotonin, and aromatic L-amino acid decarboxylase, an enzyme involved in the synthesis of serotonin. The islet B cells identified with anti-insulin immunoreactivity, which displayed a very weak formaldehyde-induced fluorescence, did not react with anti-serotonin serum.     

Studies on DNA markers (D4S10 and D4S43/S127) genetically linked to Huntington's disease in Japanese families

Summary This is the first full report on the genetic linkage between Japanese Huntington's disease and the DNA markers D4S10 and D4S43/S127. With use of the HindIII, BglI, and EcoRI polymorphisms detected at D4S10, and the combination of all these polymorphisms to give composite haplotypes, nine Japanese Huntington's disease families were found to be informative. Three recombinants for D4S10 were detected in these families, giving a maximum lod score of 1.662 at a of 0.10. Similarly, when we used the MspI and PvuII polymorphisms detected by D4S43/S127, five families gave informative results. No recombinant was detected in these families, giving a maximum lod score of 3.348 at a of 0.00. These results clearly support the view that the Japanese Huntington's disease gene may be identical with the Western gene, in spite of the lower prevalence rate in Japan.     

Enclosure experiment on the control mechanism of planktonic bacterial standing stock

In order to understand the control mechanisms of a large, stable bacterial standing stock, enclosure experiments were conducted in a eutrophic lake, where both bacterial productivity and grazing pressure were very high. Total bacterial number in the different enclosures ranged from 1.2 to 2.7×10⁷ cells mL⁻¹ throughout the experiment. The average bacterial cell production rate estimated from a grazer eliminating experiment was 6.3×10⁵ cells mL⁻¹ h⁻¹. Difference in the bacterial cell production rate between shaded and unshaded enclosures was not apparent. Bacteria showed a reduction in standing stock of only about 25–30% even after the supply of light was cut to 1%. Bacteria in the shaded enclosures then recovered their production rate in the first 12 days of perturbation. Grazing pressure in the shaded enclosures was not less than that for the control. Thus, it was considered a control mechanism of bacterial stable standing stock that the bacteria shifted their organic substrate from extracellular dissolved organic carbon freshly released from phytoplankton to that already stocked in the water column, though it is not known whether the dominant bacteria were the same.     

Recessive Nonsense Suppressors in SACCHAROMYCES CEREVISIAE : Action Spectra, Complementation Groups and Map Positions

Three genes SUP111, SUP112 and SUP113 of Saccharomyces cerevisiae have been identified that can mutate to give recessive omnipotent nonsense suppressors. Alleles of these loci can also act as allosuppressors; that is, different phenotypes, due apparently to different efficiencies of suppression, can result from different alleles at a given locus. The SUP111, SUP112 and SUP113 loci map to the right arms of chromosomes VIII, VII and XIII, respectively.     

An outbreak of staphylococcal dermatitis in laboratory mice

An epizootic of dermatitis with erosion, ulcer and crust broke out in an experimental colony of JCL-ICR mouse over a period from December 1975 to June 1976. The disease was detected in 592 of a total of 1831 mice of 3-24 months old, especially in males of 7-24 months old (517/821). At the beginning of December 1975, only a few males of 12 months old were found to have the lesion on the back skin, and thereafter the dermatitis prevailed gradually among the mice. Histopathologic examinations showed the loss of the epidermis, necrosis and/or collapse of the corium, accumulation of serous exudate with neutrophilic cell infiltration and a few cocci scattered on the surface. In chronic cases, fibrous granulation tissues with neutrophilic cell infiltration were formed in the corium. Staphylococcus aureus was isolated in pure culture from the skin lesions in all of the mice examined. Skin disease similar to that of the field case was reproduced in mice inoculated subcutaneously with 10(7) viable organisms of the fresh isolate. By giving chlortetracycline in drinking water for 7 days, treatment of the affected mice was efficacious in mild cases, but not in severe cases.     

Biological properties, phage typing and antimicrobial susceptibility of Staphylococcus aureus isolated from dermatitis in laboratory mice

The characteristics of 167 isolates of S. aureus from 106 mice suffering dermatitis were examined. All 167 isolates coagulated both rabbit and human plasmas and 161 of them also coagulated bovine plasma. All the isolates produced heat-stable and heat-labile DNase, phosphatase and yellow pigment, reduced nitrate, hydrolysed egg yolk, Tween 80, and hippurate, and grew on crystal violet agar in colonies of the negative type C and on medium with 10% NaCl. The majority of them produced fibrinolysin, protease and acetoin. Fifty-three percent were gelatinase positive. In hemolysis tests, 25, 57 and 45 isolates showed alpha-, beta-, alpha beta-hemolysis, respectively. Forty isolates did not produce hemolysins in the rabbit and sheep blood agar. All of 75 isolates tested produced acid from fructose, galactose, glucose, glycerol and mannose, but did not from arabinose, dextrin, inulin, raffinose, salicin, sorbitol and xylose. Most of these isolates produced acid from lactose, mannitol, sucrose and trehalose. All of the 75 isolates were highly sensitive to penicillin, methylphenylisoxazolyl penicillin, erythromycin, spiramycin, lincomycin, chloramphenicol, tetracycline, kanamycin, gentamicin and cephaloridine, but were resistant to sulfisoxazole. With phages of human set, all 167 isolates were typable at 100 X RTD. All but one of the typable isolates belonged to mixed lytic groups. These were I + III (35 isolates), I + M (1), I + III + M (124) and I + II + III + M (6), with long phage patterns. When the 167 isolates were biotyped as described by Hájek and Marsálek [7, 8], 5 belonged to biotype A, 1 to biotype B and 60 to biotype C.(ABSTRACT TRUNCATED AT 250 WORDS)     

A model for feature linking via collective oscillations in the primary visual cortex

A neural network model for explaining experimentally observed neuronal responses in cat primary visual cortex is proposed. In our model, the basic functional unit is an orientation column which is represented by a large homogeneous population of neurons modeled as integrate-and-fire type excitable elements. The orientation column exhibits spontaneous collective oscillations in activity in response to suitable visual stimuli. Such oscillations are caused by mutual synchronization among the neurons within the column. Numerical simulation for various stimulus patterns shows that as a result of activity correlations between different columns, the amplitude and the phase of the oscillation in each column depend strongly on the global feature of the stimulus pattern. These results satisfactorily account for experimental observations.     

Chromosome behavior in the primary nucleus ofAcetabularia calyculus as revealed by epifluorescent microscopy

Summary Chromosome behavior preceding secondary nuclei formation within a giant primary nucleus (50–100 m in diameter) inAcetabularia calyculus was observed by the fluorescence emitted from 4-6-diamidino-2-phenylindole (DAPI)-stained DNA.Throughout the period when the large nucleolus was present in the primary nucleus, thin chromonemata were observed twining around the nucleolus. Nuclear division was initiated by degeneration of the sausage-shaped nucleolus into a number of spherical subunits soon after the initiation of cap formation. On the fourth day of cap development, the chromonemata became thicker and chromomeres appeared. They accumulated adjacent to the single spherical nucleolus. The lump of chromosomes became loosened and thick chromosomes were scattered in the nucleus. The peculiar shapes of chromosomes which suggest the existence of chiasmata were frequently observed until the chromosome segregation started. This sequence of chromosome behavior seems to be the prophase of meiotic division. Chromosome segregation, the first meiotic division, occurred on the seventh day of cap development, probably being accompanied by the second meiotic division. Immediately after nuclear division of the primary nucleus, secondary nuclei were formed and cyst formation started 24 hours after repeated mitoses of the secondary nuclei.