Involvement of the neurointermediate lobe of the pituitary gland in the secretion of prolactin and luteinizing hormone in the rat

The relationship between prolactin (PRL) secretion and the neurointermediate lobe (NIL) of the pituitary gland was investigated. Plasma PRL concentrations in rats bearing anterior pituitaries autografted with or without the NIL to the renal capsule were elevated to equal extents at 1 through 6 weeks after surgery (p > 0.10). PRL levels in ovariectomized rats in which the NIL had been removed surgically (NIL-X) or only visualized (NIL-C) were 3–7 ng/ml 4, 7, and 28 days after surgery (p > 0.10); however, they were slightly higher in NIL-X $\text{vs.}$ NIL-C rats 14 days after surgery (p < 0.05). Plasma luteinizing hormone (LH) concentrations in NIL-C rats increased by 36% from 2 to 4 weeks after surgery (p < 0.05); this increase was not detected in NIL-X rats. PRL and LH surges were induced by estradiol implants in ovariectomized NIL-X and NIL-C rats; the profiles of the PRL surges were superimposable, although the magnitude of the LH surge was only 50% that in NIL-C rats (p < 0.05). These results cast doubt on the importance of the NIL in the regulation of PRL secretion either $\text{via}$ secreting hypophysiotropic hormones or $\text{via}$ conducting anterior pituitary hormones directly to the median eminence. However, the NIL may have a physiologically important role in the regulation of LH secretion.     

Some characteristics of a fast movement of auxin in intact tomato seedlings (Lycopersicon esculentum)

Using exogenous ¹⁴C-IAA, a fast movement of auxin was demonstrated in intact tomato plants ( Lycopersicon esculentum Mill, cv. Craigella) cultured in vitro. This movement is insensitive to or weakly enhanced by cold temperature (0°C) and not influenced by gravity. In short time experiments (10 min) the main part of the radioactivity which travels through the plant is IAA; in long time ones (6 h) the metabolism is much higher and leads mainly to the formation of IAAsp. The integrity of the plant is necessary for the possibility to observe such a fast movement. Isolated hypocotyl segments show only the classical polar and slow movement of auxin. Microautoradiographic techniques show that the fast movement takes place inside the plant. In the epicotyl, the vascular bundles, mainly phloem cells, are labelled; in contrast, the radioactivity detected in the hypocotyl is low, and the tracers can be visualized only inside the epidermal cells.     

The nature of formate metabolism in greening barley leaves

The metabolism of [³H]formate has been examined in etiolated and greening leaves of barley (Hordeum vulgare), dwarf bean (Phaseolus vulgarls), broad bean (Vicia faba) and corn (Zea mays). Tritium was extensively incorporated by primary leaves incubated for 20-min periods in light or dark. The organic acids and free amino acids were the principal products of formate metabolism but these and other products were more heavily labelled in green tissues. Time course experiments with barley leaves revealed a rapid labelling of serine, accompanied by increasing amounts of ³H in glycine and aspartate as the feeding period was extended. These amino acid products were formed throughout a 4-day greening period with an approximate doubling in total incorporation being due to large accumulations of tritiated glycine and aspartate. The involvement of tetrahydrofolate-dependent reactions in formate metabolism was indicated by inhibition of [¹⁴C] and [³H]formate incorporation by the folate antagonist, aminopterin. Labelling of glycine and serine was also strongly inhibited (up to 90%) when the leaves were incubated with increasing concentrations of isonicotinylhydrazide.     

An in situ assay for induced diphtheria-toxin-resistant mutants of diploid human fibroblasts

The sensitivity of diploid human fibroblasts to the cytotoxic effects of diphtheria toxin (DT) depended on the cell growth status. Exponentially growing cells treated with 10^?3-1 lethal flocculating units (LF) of DT/ml for 4 days survived with a frequency of 4 × 10^?4. However, the DT-resistant phenotype of colonies isolated under these conditions was not stable. When the growth of the cells had been arrested by confluence or deprivation of serum growth factors prior to treatment with DT (4 days, 10^?3-0.6 LF/ml), the survival decreased to 2 × 10^?6 and the resistance of isolated colonies was stable. An in situ assay for induced DT-resistant mutants was developed in order to avoid problems associated with the possible reduced viability of the mutants relative to that of wild-type cells. A reproducible and linear dose response was obtained for the induction of DT-resistant mutants by ethylnitrosourea. The mutants were induced with high frequency by this compound (e.g., 10^?3 mutants/viable cell at a 37% survival dose); complete expression of the mutant phenotype occurred after 6 generations of growth under nonselective conditions. Isolated mutant colonies showed stable resistance to DT and were cross-resistant to Pseudomonas aeruginosa exotoxin A.     

Fluence response relationship of carotenogenesis inNeurospora crassa

The fluence response of the blue light induced carotenoid synthesis inNeurospora is biphasic. Using fluence rates between 0.3 and 40 Wm^-2, increasing illumination times beyond 16 min (at 20°C) result in a second rise of the amount of carotenoids synthesized in the subsequent dark period. On altering the temperature, the transition point to the second phase of the response is shifted to shorter/longer illumination periods with increasing/decreasing temperature, respectively. The transition point can also be shifted by administering high fluence rates of near UV light: The start of the second phase is already triggered after an irradiation time of 2 min. The findings suggest that elements of the transduction sequence become depleted and senstivity recovers in a temperature-dependent process. The biphasic response and the effects of UV light are discussed in relation to the transduction mechanism and to the ecological significance.Presented in part at the meeting of the Deutsche Botanische Gesellschaft, September 1978, Marburg, Federal Republic of Germany     

Effects of nitrogen deficiency and light of high intensity onCryptomonas rufescens (Cryptophyceae)

Summary C.rufescens excystment, experimentally induced, corresponds to a general metabolism recovery of the cell, previously in a resting phase. The cytoplasm changes without any polarity, and organelles like gullet and flagella redifferentiate. The thylakoids develop mainly from the stored lipidic compounds which then disappear. Phycoerythrin immediately fills the intrathylakoidal lumen. Pigment synthesis seems closely associated with the development of membranes. The activated cell divides and the cyst wall breaks down. The destruction of the wall begins in the median layer and is followed by a mechanical rupture of the external and internal layers. Each germinative cyst releases two or four fully differentiated cells. There is an exact symmetry between excystment and encystment, all the transformations of theC. rufescens cell being reversible.     

Spore and crystal formation inBacillus thuringiensis var.thuringiensis during growth in cystine and cysteine

The effect of the addition of different concentratons of cystine and cysteine on sporulation and parasporal crystal formation inBacillus thuringiensis var.thuringiensis was studied. The effect was well pronounced when the cystine/cysteine additions were made after the stationary phase. Heat stable spores and crystals were formed when the culture was provided with a low concentration of cystine/cysteine (0.05 per cent w/v). At a moderate concentration of cystine or cysteine (0.15%), only heat labile spores were formed without the production of the crystal. When the cystine/cysteine concentration was high (0.25%), spore and crystal formation were completely inhibited. Partial reversal of inhibition of sporulation was brought about by sodium sulphate or Zinc sulphate and lead, copper, cadmium or cobalt acetate at 0.2 mM or at 0.2% of sodium or potassium pyruvate, citrate, cisaconitate, oxalosuccinate, ∞ -keto-glutarate, succinate, fumarate, malate, or oxalacetate. Glutamate (0.2%) overcame the inhibitory effect of cystine/cysteine completely. The structural changes observed using phase contrast microscopy were dependent upon the concentration of cystine/cysteine.     

Isolation of 3-(2-carboxyethyl)thymine following in vitro reaction of β-propiolactone with calf thymus DNA

3-(2-Carboxyethyl)thymine (3-CET) was synthesized from β-propiolactone (BPL) and dThd5′P at pH 9.0–9.5 via the intermediate 3-(2-carboxyethyl)thymidine-5′-monophosphoric acid (3-CEdThd5′P). 3-CEdThd5′P was converted to 3-CET by hydrolysis in 1.5 N HCl at 100°C for 2 h. The structure of 3-CET was assigned on the basis of UV spectra, electron impact (EI) and isobutane chemical ionization mass spectra and the EI mass spectrum of a trimethylsilyl derivative of 3-CET. BPL was reacted in vitro with calf thymus DNA at pH 7.5. 100 A units of BPL-reacted DNA yielded, following perchloric acid hydrolysis and preparative paper chromatography, 3 A units of 3-CET. Reaction of BPL with the phosphodiester thymidylyl-(3′-5′)thymidine gave 3-(2-carboxyethyl)thymidylyl-(3′-5′)-3-(2-carboxyethyl)thymidine (～3%). Phosphotriester formation was not detected.     

A requirement for three cell types for in vitro generation of specific secondary cell-mediated cytotoxic response against SV40-induced tumor-associated antigens in mice

The present study demonstrates that a collaborative interaction among three cell types, namely, two distinct subsets of T cells and macrophages is needed for in vitro generation of specific secondary cell-mediated cytotoxicity against syngeneic SV40-transformed cells in mice. These data suggest a central role of three cell types in the generation of efficient antitumor immune response in syngeneic tumor systems.