The segregation of lambs into ‘responders’ and ‘non-responders’: Response to vaccination with irradiated Trichostrongylus colubriformis larvae before weaning

Random bred Merino ram and ewe lambs were vaccinated at 1, 2 and/or 3 months of age with irradiated T. colubriformis larvae. An exponentially increasing challenge of normal larvae was given to all groups including unvaccinated controls commencing at 1 month of age. The results, based on faecal egg counts, showed a dissociation into animals which responded to vaccination (geometric mean egg count 441) and those which did not (geometric mean egg count 1567). The proportion of responders was greatest in groups first vaccinated at the earliest age (1 month). Wool growth and liveweight gains showed severe depression corresponding to peak egg counts, however, responders were less affected than non-responders. There was no correlation between haemoglobin type and resistance to challenge. Faecal egg counts after impulse challenge with 10,000 normal larvae given at about 6$\text{1}\text{2}$ months of age showed a significant ranked correlation with those obtained during the primary exponential challenge. These results confirm that a proportion of young lambs respond to vaccination with irradiated larvae, and that genetically-determined factors are implicated in the ability of animals to respond to vaccination at an early age.     

Age- and density-dependent growth within populations of the ectoparasitic digenean Transversotrema patialense on the fish host

Mills C. A. 1980. Age- and density-dependent growth within populations of the ectoparasitic digenean Transversotrema patialense on the fish host. Internationaljournal for Parasitology, 10: 287–291. Growth of the adult ectoparasitic digenean Transversotrema patialense on the fish host Brachydanio rerio is shown to be age-dependent, ceasing 15–20 days post infection. The vitelline glands expand greatly in size after infection from 1.25 % of cercarial area to 20.7 % of that of the mature adult. There is an increase in the occurrence of reproductive abnormalities in old parasites but this alone fails to account for the decline in egg production found as populations of T. patialense age. Growth of adult T. patialense is density-dependent with reduced growth at high initial parasite densities per host.     

Chemically defined media for growth and sporulation of Entomophthora virulenta

Amino acids, salts, and vitamins were combined with dextrose to test their effect on growth and sporulation of Entomophthora virulenta in liquid shake culture. The addition of a vitamin solution to the tested media did not enhance growth or sporulation. MgSO₄·7H₂O was the only salt individually tested that allowed for good growth and sporulation. MgSO₄·7H₂O concentrations exceeding 250 mg/liter in media lacking other salts inhibited sporulation. A simple medium of l-arginine, l-leucine, glycine, and mineral salts allowed high growth and sporulation.     

Demonstration of growth in porcine thyroid cell culture

Eagle's minimum essential medium supplemented with 20 per cent newborn calf serum (N.C.S.) allows porcine thyroid cell survival but not cell growth in vitro. In NCTC 109 medium supplemented with 20 per cent N.C.S. these cells actively grow and may be serially propagated. Cell population doubling time expressed as DNA doubling value is 3.5 days at 37 degrees C in 95 per cent air-5 per cent CO2. Thyrotropin does not affect porcine thyroid cell multiplication in vitro but stimulates the plating efficiency in primary cultures to about 130 per cent of controls. Cell selection was obtained by replacing media with Earle's balanced salt solution. This operation provoked death of nearly all cells by day 18 but subsequent addition of growth medium resulted in proliferation of epithelial cell clones. From generation 2 to generation 8, cells produce thyroglobulin but they do not actively trap iodide nor form follicles when thyrotropin is added to the media. Cell selection, demonstration of growth, as well as freeze-storage techniques described in this paper permit selection and storage of porcine thyroid cells and the potential constitution of cell collections.     

Chemoautotrophic growth of Rhodopseudomonas species with hydrogen and chemotrophic utilization of methanol and formate

A chemolithoautotrophic type of metabolism, which was hitherto unknown for purple nonsulfur bacteria, was demonstrated by growth experiments using Rhodopseudomonas capsulata Kb1 and Rhodopseudomonas acidophila 10050. These strains were able to grow in a mineral medium in the dark at the expense of H₂, O₂, and CO₂. A minimum doubling time of 9 h was obtained for R. capsulata under an atmosphere containing less than 15% oxygen; higher oxygen concentrations suppressed autotrophic but not chemoorganotrophic growth. Oxygen sensitivity of chemoautotrophically growing cells of R. acidophila was even more pronounced, whereas cells growing chemotrophically on methanol almost tolerated the oxygen concentration of air. Highest oxygen sensitivity of growth of R. acidophila was observed with formate as substrate. The growth yield of cultures grown semiaerobically in the dark on methanol was 0.23 g dry cell material per g methanol consumed.     

Stimulation of human vascular endothelial cell growth by a platelet-derived growth factor and thrombin

Repair of a vascular wound is mediated by migration and subsequent replication of the endothelial cells that form the inner lining of blood vessels. We have measured the growth response of human umbilical vein endothelial cells (HuE) to two polypeptides that are transiently produced in high concentrations at the site of a wound; the platelet-derived growth factor (PDGF) and the protease thrombin. When 10⁴ HuE cells are seeded as a dense island (2-mm diameter) in the center of a 16-mm tissue culture well in medium containing 20% human serum derived from platelet-poor plasma (PDS), no increase in cell number or colony size is observed. With the addition of 0.5 ng/ml partially purified PDGF, colony size increases and the number of cells after 8 days is 4.8 × 10⁴. When human thrombin (1 μg/ml) is added along with the PDGF, the cell number rises to 9.2 × 10⁴. Thrombin alone stimulates no increase in cell number. Although partially purified PDGF stimulates endothelial cells maintained in PDS as well as those maintained in whole blood serum (WBS), pure PDGF is active only when assayed in medium that contains WBS and is supplemented with thrombin. These results suggest the existence of a second class of platelet-derived factors that enable HuE cells to respond to the mitogenic activity of the purified platelet mitogen and thrombin.     

Some features of feeding,respiration and energy conversion of Dapnia Magna

Some results of studies with Daphnia magna are presented. These results can be used as background information for toxicologists, but the techniques referred to might well be used for toxicity tests. Daphnia magna is a filter-feeder. With the Coulter Counter it was shown that the feeding mechanism is aselective for size of the food particles. It was also shown that algal cells can pass the gut of Daphnia magna several times before being completely digested. The uptake of food is proportional to the food concentration up to a critical concentration. Above this concentration the food uptake is constant. Respiration is also dependent on the food concentration, and has a maximum value at food concentrations near the critical concentration of the feeding process. Growth efficiency is independent of the food concentration. The effect of temperature on the feeding process is different for low and high food concentrations. Growth efficiency is maximal at 10°C and above 22°C growth efficiency was negative, which means that the population cannot survive under the experimental conditions used, at temperatures above 22°C.     

Hormonal effects on diosgenin biosynthesis and growth in Dioscorea deltoidea tissue cultures

Analysis of Dioscorea deltoidea tissue cultures grown in the presence of 2,4-D, indole-3-butyric acid, isopentenyladenine, benzyladenine and GA singly and in combination showed that the medium with 2,4-D most consistently favored diosgenin production. GA and high benzyladenine concentrations were toxic.     

Effect of sodium butyrate on mammalian cells in culture: A review

Summary Sodium butyrate produces reversible changes in morphology, growth rate, and enzyme activities of several mammalian cell types in culture. Some of these changes are similar to those produced by agents which increase the intracellular level of adenosine 3′,5′-cyclic monophosphate (cAMP) or by analogs of cAMP. Sodium butyrate increases the intracellular level of cAMP by about two fold in neuroblastoma cells; therefore, some of the effects of sodium butyrate on these cells may in part be mediated by cAMP. Sodium butyrate appears to have properties of a good chemotherapeutic agent for neuroblastoma tumors because the treatment of neuroblastoma cells in culture causes cell death and “differentiation”; however, it is either innocuous or produces reversible morphological and biochemical alterations in other cell types.     

Some physiological observations on the uptake of d-glucose and 2-deoxy-d-glucose by starving and exponentially-growing yeasts

Some methods for measuring the uptake of sugars by yeasts were investigated critically. A study was made of the effects of starvation of Pichia pinus, Candida utilis, Saccharomyces cerevisiae and Rhodosporidium toruloides on their uptake of d-glucose and 2-deoxy-d-glucose. Marked changes in the rates of uptake of these sugars occurred during 10 h of starvation, including (a) an immediate increase of up to 75% above that for growing cells and (b) a continuous decline to as little as 4%. Each yeast behaved differently. The rates did not remain constant during the periods of starvation often used for studies on the transport of sugars into yeasts. For Pichia pinus, there were striking differences, associated with starvation, between the transport of 2-deoxy-d-glucose and d-glucose, despite evidence that the two sugars enter this yeast by means of the same carrier. Some physiological explanations for these findings are discussed.