Developmental Stages of the Society Finch, Lonchura striata var. dornestica.

The society finch, a little passerin, was purposed to be utilized in embryological studies. Under control of the breeding cycle in 20 pairs, 4 to 6 eggs were used to be laid daily for several repeating week in a year. Average incubation time was 17 days in contrast to 21 in the domestic fowl. The eggs weighed 1.1 g in average and expected smallness of the embryo was regarded as favorable for morphological studies including the scanning electron microscopy. We present the first report of the complete development of the society finch. A number of embryological characteristics are described with special reference to the peculiarity of the altricial finch as compared with the precocial domestic fowl.     

Reactivity of a Monoclonal Antibody Raised against Human Leukemic Cells to Embryonic and Adult Tissues of the Mouse and Teratocarcinomas

C-9-1, a monoclonal IgM antibody raised against human null cell acute lymphocytic leukemia cells reacted with restricted regions of embryonic and adult tissues of the mouse. The antigen positive sites in the embryos included embryonic ectoderm, visceral endoderm, trophoblastic cells invading the maternal decidua of 5∼7-day embryos, primordial germ cells of 10∼12-day embryos, epithelium of nasal chamber, the bronchus, Mullerian duct, epididymis and bladder of 12∼17-day embryos. In the adult mice, C-9-1 antigen was detected in renal tubules, a part of stomach, bladder, endometrium and epididymal sperm. Embryonal carcinoma cells, but not endodermal cells of teratocarcinoma expressed the antigen. Thus, C-9-1 antigen showed distribution similar to SSEA-1. However, C-9-1 antigen was not detected in preimplantation embryos, nor in oviduct, both of which are positive for SSEA-1.     

Studies on chloroplast development in Chlamydomonas reinhardtii I. Effect of brief illumination on chlorophyll synthesis

When dark grown cells of Chlamydomonas reinhardtii y-1 mutantwere exposed to continuous light, an immediate transformationof small amounts of protochlorophyll(ide), which had been presentin the dark grown cells, to chlorophyll was observed. Afterthis, there was a slow accumulation of chlorophyll lasting for2.5-3 hr before the start of exponential synthesis. Initialaccumulation of chlorophyll was distinctly slower at a highlight intensity (13,000 lux) than it was at moderate intensitiesof light (2,000–5,000 lux). However, the exponential synthesisof chlorophyll started after the same 2.5–3 hr of illumination. A brief pre-illumination of cells followed by incubation indarkness was effective in promoting chlorophyll synthesis undersubsequent continuous illumination at high, as well as moderatelight intensities. Pretreatment alleviated retardation of theinitial chlorophyll accumulation by light of high intensity.The promoting effect of preillumination on chlorophyll synthesiswas sufficient, even when a light impulse as short as 10 secwas given. However, the effect was dependent on length of thedark period after the short pre-illumination. The full extentof this effect was observed when the dark period was about 2.5–3hr long. Further dark incubation gradually decreased the effect. On the basis of these findings, it is assumed that a factor(s)responsible for promotion of chlorophyll (or chloroplast) synthesisin the process of greening of dark grown cells is produced duringthe dark period after a brief pre-illumination, and that thefactor is turned over at a relatively fast rate. The possiblenature of the presumed factor is discussed in relation to chloroplastdevelopment. ¹Present address: Department of Biology, Faculty of Science,Kobe University, Nada-ku, Kobe, Japan. (Received August 18, 1970; )     

Purification and Characterization of Isocitrate Lyase from Ethanol-grown Euglena gracilis

Isocitrate lyase was purified to homogeneity from ethanol-grown Euglena gracilis. The specific activity was 0.26 μmol/min/mg protein. The molecular mass of the enzyme was calculated to be 380 kDa by gel filtration on a Superose 6 column. The subunit molecular mass of the enzyme was 116 kDa as determined by SDS-polyacrylamide gel electrophoresis. These results showed that the native form of this enzyme was a trimer composed of three identical subunits. The pH optimum for cleavage and condensation reactions was 6.5 and 7.0, respectively. The K_m values for isocitrate, glyoxylate and succinate were 3.8, 1.3 and 7.7 mM, respectively. Isocitrate lyase absolutely required Mg for enzymatic activity. This is the first report of the purification of isocitrate lyase to homogeneity from Euglena gracilis.     

Relation Between Cell Union and Nuclear Reorganization in Triplet Conjugants of Paramecium caudatum and Paramecium multimicronucleatum

SYNOPSIS Triplet conjugants of Paramecium caudatum which appeared naturally in mating mixtures and those of Paramecium multimicronucleatum which were produced by conjugation-inducing chemicals were isolated. Triplet conjugants lasting for more than 3 h were stained to examine macronuclear events. In P. caudatum , only 2 triplets among 182 (1%) contained macronuclear fragmentation in all 3 members. The most frequently occurring triplets (79%) were those producing 1 cell without and 2 cells with macronuclear fragments. There were also triplets (17%) producing 1 cell with, and 2 without macronuclear fragments, and some (3%) with 3 cells that contained no fragments. The length of persistence of the triplet was not responsible for the occurrence of macronuclear fragmentation in the 3rd cell of the triplet. In P. multimicronucleatum , the same 4 classes of triplets occurred, but the most frequently occurring class was that consisting of 3 cells (91%) with macronuclear fragments. Induction of nearly 100% of triplets with 3 such cells was possible by isolating the triplets' from a culture which was treated chemically at about 24 h after the last feeding. Treatment with chemicals in starved cultures resulted in triplets with incompletely fragmented or nonfragmented macronuclei. Further, in P. multimicronucleatum , chemicallyinduced triplets involving only holdfast pairs to which the 3rd cells were uniting often produced 3 cells with fragmented macronuclei.     

COMPARISON OF NEURONAL AND LENS PHENOTYPE EXPRESSION IN THE TRANSDIFFERENTIATING CULTURES OF NUERAL RETINA WITH DIFFERENT CULTURE MEDIA*

The effects of three different culture media (Eagle's MEM, F-12 and L-15) on the transdifferentiation of 8-day chick embryonic neural retina into lens cells, were examined with respect to the expression of two phenotypes. One type referred to neuronal specificity (as represented by the level of cholineacetyl-transferase, CAT, activity) and the other to lens specificity (as represented by content of α-and δ-crystallin). In 7-day cell cultures before the visible differentiation of lentoid bodies, CAT activity was detected in all media. But, its level was about 9 times higher in cultures with L-15 than in those with MEM and 3 times higher than in F-12. In 26-day cultures, CAT activity was practically undetectable. The production of α-and δ-crystallin was detected in cultures at 26 days. There were quantitative differences in the crystallin content with different media, and it was highest in cultures with L-15. The results indicate that conditions most favourable to the maintenance of the neuronal specificity in cell cultures of neural retina, can also support the most extensive transdifferentiation. The possibility of direct transdifferentiation of once neuronally specified cells into lens cells in cultures with L-15 has been suggested to explain the present results.