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.     

RADIOAUTOGRAPHIC LOCALIZATION OF THE INCREASED SYNTHESIS OF PHOSPHATIDYLINOSITOL IN RESPONSE TO PANCREOZYMIN OR ACETYLCHOLINE IN GUINEA PIG PANCREAS SLICES

A technique is described for measuring the incorporation of myo-inositol-2-³H into the lipid of various regions of the guinea pig pancreatic acinar cell by radioautography. Stimulation of enzyme secretion with either pancreozymin or acetylcholine was associated with increased graining in both the basophilic cytoplasm and the nonbasophilic cytoplasm. Kinetic studies suggested that the incorporation of myo-inositol-2-³H was stimulated independently in the two regions. Most of the increment in graining due to stimulation with pancreozymin or acetylcholine plus eserine was abolished if the tissue was extracted with 2:1 chloroform-methanol before radioautography. On chromatography of lipid extracts of pancreas, the only lipid showing a detectable increment in radioactivity on stimulation with pancreozymin was phosphatidylinositol. Thus, essentially all of the increment in graining is likely to be due to increased incorporation of tritium into phosphatidylinositol. These studies, coupled with earlier studies employing differential centrifugation, indicate that on stimulation of enzyme secretion there is increased synthesis of phosphatidylinositol in the rough-surfaced endoplasmic reticulum and in the smooth-surfaced Golgi membranes. The significance of these observations is discussed in connection with membrane circulation presumed to occur in the pancreatic acinar cell on stimulation of protein secretion. It is suggested that the increased synthesis of phosphatidylinositol may be concerned with the formation of new endoplasmic reticulum and possibly Golgi membrane to replace that which is presumably converted to membrane of the zymogen granules during intracellular protein transport.     

Some Properties of Heat-Resistant and Heat-Sensitive Strains of Clostridium perfringens I. Heat Resistance and Toxigenicity

Heat resistance at 100 C (D-values), sporulating ratios, toxigenicity for mice, and lecithinase activity (as micrograms per milliliter of enzyme, ascertained by the lecithovitellin reaction) were determined for four strains of Clostridium perfringens. A definite inverse relationship between thermal resistance and toxigenicity was found. The D-values ranged from 17.6 for the most heat-resistant strain to 0.3 for the strain possessing the least heat resistance, with corresponding lecithinase activities from 25 to 133 mug/ml of enzyme. The sporulating ratios did not differ greatly between the strains. The heat stability of the toxin was greater at 100 C than at 75 C. There was a noticeable difference between the heat stabilities of the toxin in the culture fluids of the heat-sensitive and heat-resistant strains at pH 7.0 when the toxic filtrates were held at 100 C. At a holding temperature of 75 C, a similar but lesser difference was observed at pH 5.5. Heat resistance and lecithinase activity did not change when a substrain of the least heat-resistant parent strain was obtained through heat selection by a single transfer, or when the most heat-resistant strain was transferred serially 12 times.     

The incidence of double-yolked eggs in relation to improvement in egg production

Summary The production of double-yolked eggs and its relation to other egg production traits has been summarized over a period of thirty years for a closed flock selected for gains in total egg production.The number of double-yolked eggs per pullet as well as the percentage of pullets laying at least one double-yolked egg have increased rather steadily, although it is evident that the trait possesses no selective advantage. Pullets which laid double-yolked eggs showed earlier sexual maturity and superiority in egg production but it is clear that the corresponding genetic correlations are low or negligible.The heritability of the trait increased with its level of incidence and is sufficiently high that selection should increase the incidence to a level permitting further study of multiple ovulation.

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Zusammenfassung An einer für eine Steigerung der Ei-Produktion ausgewählten Herde Weißer Leghornhühner wurde der Anfall von Eiern mit zwei Dottern und ihre Beziehung zu anderen Merkmalen der Ei-Produktion für einen Zeitraum von 30 Jahren zusammengestellt.Die Anzahl doppeldottriger Eier je Hühnchen und der Prozentsatz Hühnchen, die wenigstens ein doppeldottriges Ei legten, ist ziemlich konstant geblieben, wenn auch dieses Merkmal offensichtlich keinen Selektionswert hat. Hühnchen, die Eier mit zwei Dottern legten, zeigten eine frühere Geschlechtsreife und eine höhere Ei-Produktion, aber es ist klar, daß die entsprechenden genetischen Korrelationen niedrig sind.Die Erblichkeit des Merkmals stieg mit seinem Auftreten, sie ist hoch genug, daß eine Selektion das Auftreten noch steigern könnte, um eine weitere Untersuchung der mehrfachen Ovulation zu ermöglichen.

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Dedicated to Professor Hans Stubbe on the occasion of his 65^th birthday.     

THE DEVELOPMENT OF THE SEED OF ABUTILON THEOPHRASTI I. OVULE AND EMBRYO

Winter , Dorothy M. (Iowa State U., Ames.) The development of the seed of Abutilon theophrasti. I. Ovule and embryo. Amer. Jour. Bot. 47(1): 8–14. Illus. 1960.—Abutilon theophrasti Medic, is a widespread annual weed which produces an abundance of seed in capsules which mature within 20 days after pollination. Ovule differentiation may be observed at least 8 days before anthesis when a sporogenous cell becomes evident and 2 integuments are initiated. An 8-nucleate embryo sac is produced from the chalazal megaspore approximately 2 days before anthesis. The outer integument of the mature campylotropous ovule consists of 2 cell layers, the inner integument has 6 to 15 cell layers. The initially free-nucleate endosperm becomes cellular betwen 3 and 7 days after pollination. At maturity a thin layer of gelatinous endosperm encases the embryo. The Asterad-type proembryo of Abutilon has a stout suspensor and develops rapidly. Four days after pollination cotyledons are initiated; 4 days later a leaf primordium is evident. Fifteen days after pollination the embryo, which has essentially completed its growth, consists of a large hypocotyl with root promeristem and root cap at its basal end, and 2 flat, folded, leaflike cotyledons enclosing a small epicotyl at its upper end. The epicotyl consists of an embryonic leaf and a stem apex.     

Chromosomal localization of human genes required for G1 progression in mammalian cells

Specific probes derived from the human genes that complement the mutations of two independent temperature-sensitive (ts) mutants of the BHK-21 hamster cell line were used to determine the chromosomal locations of the loci in the human genome. The ts11 gene, which complements a mutation that blocks progression through the G1 phase of the cell cycle and which has now been identified as the structural gene for asparagine synthetase, is a member of a small gene/pseudogene family with four members. In a rodent-human somatic cell hybrid panel, the ts11 genomic locus from which the genomic probe derives segregates with human chromosome region 7cen----7q35, proximal to the TCR beta locus. In situ hybridization maps this locus more precisely to the q21-31 region of chromosome 7. Two other members of the gene family detected by the ts11 probe segregate concordantly with chromosome region 8pter----8q24 and chromosome region 21pter----21q22. Similar experiments using the same rodent-human hybrid panel conducted with a probe identifying the tsBN51 gene, which also encodes a function necessary for G1 progression, mapped this locus to human chromosome 8, proximal to the large amplification unit encompassing the c-myc gene of Colo320 cells. Chromosomal in situ hybridization of the tsBN51 probe confirmed the localization of this gene to chromosome 8, with the most likely location of the gene being 8q21.