Substrate effects in tower loop reactors

Summary Hansenula polymorpha was cultivated in a bubble column loop bioreactor employing ethanol and/or glucose as substrates. By varying the substrate concentration, the cultivations were carried out in non-limited, substrate limited and oxygen transfer limited growth ranges. The influence of the transitions from one range to another on reactor performance (OTR,k _L a, a) and cell productivity () were investigated. When employing ethanol as a substrate, the concentration considerably influences the fluid dynamics, mass transfer phenomena and cell productivity. When employing glucose as a substrate, glucose repression occurs. At high glucose concentrations no transition into the oxygen transfer limited growth is possible. The ethanol produced during the glucose repression influences the fluid dynamics, mass transfer phenomena and productivity. With decreasing glucose concentration the glucose repression can be gradually eliminated.     

Foam behaviour of biological media

Summary A simple method was developed for evaluating foam stability. The influence of KCl and MgSO₄ on foam stability of bovine serum albumin foams was investigated. These salts increase foaminess, but diminish foam stability by the same degree. Thus there is little overall.     

The isolated perfused rabbit ovary — A model for studies of ovarian function

Summary In the present investigation the ultrastructure of isolated rabbit ovaries, perfused with different media for various time periods, was studied. The steroid hormone production by the perfused ovary was also determined. Perfusion with Medium 199 results in prominent interstitial ovarian oedema which increases with perfusion time. Even after the addition of 6–10 % Dextran T40, oedema appears in the interstitial tissue of the ovary. Perfusion solutions with osmotically active colloid particles of large molecular size (Dextran T70; average molecular weight 70,000 and bovine serum albumin), cause less distortion in the ovarian structure, and ultrastructurally the ovarian tissues appear essentially the same as in the control ovaries.The results indicate that the perfused rabbit ovary, under strictly controlled conditions, can be used as an experimental model for studies of various aspects of ovarian function, including follicular rupture.     

The flagellar root apparatus,the microtubular system and associated organelles in the chrysophycean flagellate,Poterioochromonas malhamensis Peterfi (syn.Poteriochromonas stipitata Scherffel andOchromonas malhamensis pringsheim)

Summary The two flagella ofPoterioochromonas are inserted in an apical platform which is shaped by six long flagellar root fibres. The arrangement and structure of these root fibres are described in detail. One of these fibres is the single nucleating site for cytoplasmic interphase microtubules which extend peripherally down to the cytoplasmic tail. Another fibre proceeds toward the centre of the cell and passes the nucleus but is different in structure, position and function from the striated rhizoplast found in many chrysophycean flagellates which is observed but vestigial inPoterioochromonas.A specific kinetosomal mitochondrion has a threefold attachment to the flagellar root apparatus. The chloroplast is also bound to the root system. It has no stigma, but a special continuation of the periplastidial cisterna is developed instead. Another cisterna extends from the nuclear envelope-dictyosome interspace to the kinetosome of the long flagellum. The functional and taxonomic meanings of these structures and of their mutual arrangement are discussed. It is concluded that the present strain (no. 933-1 a of the Collection of Algal Cultures at the Institute of Plant Physiology, Göttingen) has to be excluded from the genusOchromonas.     

Effect of sensory stimulation on the lamina V pyramidal neurons of the gyrus cinguli in the rat

Three groups of Wistar-rats were exposed to permanent noise (80 db) during different periods in their postnatal life: the first group was exposed starting from birth for a period of four weeks, the second one from birth up to nine weeks of age and the third group from the fifth up to the ninth week postnatal. A fourth group (control animals) was reared under normal laboratory conditions. After the experiments the brains were exposed to a modified GOLGI-method. In lamina-V-pyramids of the gyrus cinguli lightmicroscopical results: length, number and distribution of spines on the main apical dendrites and on the apical dendritic branches where evaluated. Main results: 1. Permanent noise during the early postnatal development phase of the brain of rats (from birth up to the fourth week of age) causes a statistically significant increase of apical spines. The spines-values are 20% above those of the control animals. 2. Permanent noise from birth up to the ninth week of age or applied only during the later postnatal period (from the fifth week up to the ninth week of age) does not significantly alterate the spines-value. 3. The results are estimated as a consequence of extreme environmental factors causing effects, comparable with an universal stress reaction. Conclusions were discussed in comparison to the results of other authors.     

A new progestin (Sa 45.249) for cycle control in pigs communication I: Hormonal activities and dosage

Sa 45.249 was applied for 12 days to groups of ten gilts each. A daily dose of 3, 6, 12 or 24 mg inhibited cyclic functions effectively; estrus was observed 4.5 ± 0.8, 4.8 ± 0.8, 5.2 ± 0.9 and 6.1 ± 0.6 days after cessation of treatment, respectively. All animals were slaughtered 8 days after induced estrus. Only animals treated with 3 mg showed a high incidence of ovarian cysts simultaneously with the occurrence of corpora lutea. In animals treated with higher dosages, only one (6 mg) had 4 cystic follicles, but simultaneously 12 corpora lutea. In another study, the effectiveness of Sa 45.249, applied at different doses, for differing time periods, and starting at different days of the cycle, was investigated. Doses ranged from 3 to 9 mg/day, duration of treatment from 8 to 16 days and treatments commenced on days 2, 5, 10, 15 or 19 of the cycle. An increase in the daily doses of 1 mg resulted in a delay of estrus of less than 0.1 day. Of 99 gilts, 93 showed an estrus 6.5 ± 1.7 days after cessation of treatment. None of the variables studied had a significant effect on the occurrence of estrus or the interval between treatment and the onset of heat.