Cytological aspects of haemoglobin and chlorocruorin synthesis in polychaete annelids

Summary The ultrastructure of the haematopoietic cells in the polychaetes Neoamphitrite figulus Dalyell, Lanice conchilega (Pallas), Arenicola marina (L.), Myxicola infundibulum Renier, Megalomma vesiculusom (Montagu), Sabella penicillus L., are compared: all show similarities in having well developed Golgi, granular endoplasmic reticulum and haemoglobin or chlorocruorin in vesicles, and numerous mitochondria. The porphyrin byproducts of synthesis are combined with iron as haematins within electrondense granules built up from multi-lamellar organelles. The structure of the basal lamina which alone separates the cells from the lumen of the vessels is described and evidence is presented for the method of release of the haem into the plasma by reverse pinocytosis. The cycle of synthesis within the cell is discussed and the process of haem synthesis in annelids is reviewed. The structure of the haemoglobin-containing coelomocytes of Neoamphitrite figulus is briefly described.This work was made possible by an award from the Science Research Council. We would also like to thank the Director and Staff of the Plymouth Laboratory, where some of the work was done, for their hospitality and facilities.     

ANTIBODY-PRODUCING CELLS: ANALYSIS AND PURIFICATION BY VELOCITY SEDIMENTATION

Velocity sedimentation cell separation is a simple and reproducible method for obtaining highly enriched populations of viable antibody-producing cells. Using suspensions of spleen cells prepared from mice immunized with sheep erythrocytes, fractions containing up to 2% 19S-PFC and 25% 7S-PFC can be obtained. Granulocytes constitute almost all of the remaining cells in these fractions. The sedimentation profile of 7S-PFC is very broad in comparison with that of cell populations known to be homogeneous in size (e.g. mouse erythrocytes). Analysis of the profile of 7S-PFC at different times after immunization suggests that the heterogeneity arises largely from the doubling in cell volume as a cell moves from one mitosis to the next. Early in the immune response, when the majority of the PFC are proliferating, the variation in sedimentation velocities is consistent with such a two-fold variation in cell volume. Late in the response, when most PFC have stopped proliferating, the sedimentation profile is more homogeneous. This analysis suggests that the fractionation procedure is sensitive enough to separate PFC according to their position in the cell cycle. Sedimentation velocities were also measured for several other classes of cells found in spleen. Comparison of these values shows that sedimentation velocity is a useful parameter for characterizing different types of cells.     

Sporicidal Activity of Sodium Hypochlorite at Subzero Temperatures

Sodium hypochlorite was an excellent disinfectant at low temperatures. With the addition of ethylene glycol to prevent freezing, hypochlorite solutions at low free available chlorine concentrations, were effective against Bacillus subtilis var. niger spores from 0 to -40 C. The effectiveness of this decontaminant was influenced by temperature, pH, and concentration, with pH 7.2 the optimum for decontamination at all temperatures and concentrations.     

Novel Multi-Slit Large-Volume Air Sampler

Scientific investigators who are interested in the various facets of airborne transmission of disease in research laboratories and hospitals need a simple, continuous, high-volume sampling device that will recover a high percentage of viable microorganisms from the atmosphere. Such a device must sample a large quantity of air. It should effect direct transfer of the air into an all-purpose liquid medium in order to collect bacteria, viruses, rickettsia, and fungi, and it should be easy to use. A simple multi-slit impinger sampler that fulfills these requirements has been developed. It operates at an air-sampling rate of 500 liters/min, has a high collection efficiency, functions at a low pressure drop, and, in contrast to some earlier instruments, does not depend upon electrostatic precipitation at high voltages. When compared to the all-glass impinger, the multi-slit impinger sampler collected microbial aerosols of Serratia marcescens at 82% efficiency, and aerosols of Bacillus subtilis var. niger at 78% efficiency.     

Studies on Microbial Ribonucleic Acid VI. Appearance of Methyl-deficient Transfer Ribonucleic Acid During Logarithmic Growth of Saccharomyces cerevisiae

Transfer ribonucleic acid (tRNA) that is deficient in methyl groups may be detected in logarithmically growing Saccharomyces cerevisiae. The amount of methyl-deficient tRNA is not constant throughout the logarithmic phase, but is maximal about one generation before the onset of the late growth phase. During this latter phase, the tRNA is fully methylated. The methyl-deficient tRNA is present during a period of high metabolic activity of the cell, characterized by increased RNA and protein content.     

Sporicidal Activity of Peracetic Acid and β-Propiolactone at Subzero Temperatures

A method was developed to evaluate and measure the sporicidal activity of peracetic acid (PAA) and beta-propiolactone (BPL) at subzero temperatures as low as -40 C. Bacillus subtilis var. niger spores were used as the test organism. Both PAA and BPL were sporicidal at low temperatures, with PAA the more active. The temperature coefficients of the two chemicals are generally low over a range of 20 to -20 C, but increase significantly at temperatures below this. Results showed an initial lag in the PAA death rates that was directly dependent on the temperature. BPL did not show this lag time.     

Certification of Probability of Sterilization of Liquid by Filtration

Four types of hydrosol filters, two reusable (diatomaceous cylinder and fritted-glass funnel) and two disposable (asbestos pad and membrane filter) were challenged with a heavy bacterial suspension to assess their ability to produce sterile filtrates. Two of the four diatomaceous earth filters, the four fritted-glass funnels, and all of the asbestos pads tested generally gave sterile filtrates. However, only one type of filter, one of the membranes in its manufacturer's own holder, consistently gave sterile filtrates. The two other types of membranes usually gave sterile filtrates if tested in one manufacturer's holder, but all types invariably gave contaminated filtrates when tested in another manufacturer's holder. Contaminated filtrates were generally attributed to a poor reusable filter or to a faulty holder used with a disposable filter. If a high degree of certainty is required for sterile heat-labile filtrate, it is suggested that the liquid be passed through two or more filters in a previously tested and proven system.     

GIANT CENTRIOLE FORMATION IN SCIARA

Although somatic tissues of Sciara contain 9-membered centrioles, germ line tissues develop giant centrioles with 60–90 singlet tubules disposed in an oval array. Some 9-membered centrioles still may be seen in second instar spermatogonia. Each of these centrioles is associated with a larger "daughter" or secondary centriole at right angles to it. Most centrioles of second instar spermatogonia consist of 20–50 singlet tubules arranged in an oval, sometimes associated with an even larger secondary centriole. The more recently formed centriole of a pair is distinguishable from its partner by a concentric band of electron-opaque material inside its tubules. If a pair of centrioles at right angles to each other is pictured as a "T" formed by two cylinders, the secondary centriole is always the stem of the T; the primary centriole is the top. The two centrioles are oriented at the pole of the mitotic spindle so that the tubules of the primary centriole are parallel to the spindle axis. Each daughter cell receives a pair of centrioles and, during interphase, each of these centrioles gives rise to a new daughter centriole. A Golgi area of characteristic morphology is found in association with centrioles shortly after two new ones have formed. We conclude that in Sciara a centriole may give rise to a daughter morphologically different from itself. Whether the daughter is a 9-membered or giant centriole depends on the tissue type and stage of development.