Moss production in a black spruce Picea mariana forest with permafrost near Fairbanks,Alaska, as compared with two permafrost-free stands

During the 1975 and 1976 seasons the net primary production of five common bryophytes in different stands of mature vegetation near Fairbanks, Alaska was investigated. Overall annual moss production at the intensive black spruce site was about 120 g m^?1 yr^?1 or about twice as high as the corresponding annual spruce production. Maximum rates of net photosynthesis varied from 2.7 mg CO₂ g^?1 h^?1 in Polytrichum commune Hedw. to 0.6 mg CO₂ g^?1 h^?1 in Sphagnum nemoreum Scop. The photosynthesis of overwintered leaves early in the season was low and as a result of new growth a steady increase in net photosynthesis occurred throughout the season. Leaf water content was found to be the most important limiting factor for growth under natural conditions. There was a strong increase in growth and photosynthesis of Sphagnum nemoreum after application of N and P, indicating nutrient deficiency.     

Environmental Chemicals and Nervous System Dysfunction

Selected examples of associations between nervous system diseases and exposures to occupational and environmental chemicals have been reviewed. Recent outbreaks of human neurotoxicity from both wellknown and previously unknown toxicants reemphasize the need for the medical community to give increased attention to chemical causes of nervous system dysfunction.     

Protein-bound sulfhydryl groups and thiolesters in mitochondria and submitochondrial particles and their relationships to oxidative phosphorylation

Procedures are described for measurement of total protein-bound —SH groups and apparent thiolester linkages in mitochondrial preparations. The procedure for total —SH is based on reaction with radioactive p-mercuribenzoate in 6 m guanidine hydrochloride at pH 9 containing 1 m ammonia buffer. The procedure for apparent thiolesters is based on alkylation of available — SH groups in 6 m guanidine hydrochloride, protein precipitation with perchloric acid, and ammonolysis at pH 9 to liberate — SH from any thiolester present.No variations in total —SH groups measured in Submitochondrial particles or in mitochondria were noted with presence or absence of ATP, ADP, substrates, or uncouplers of oxidative phosphorylation. Previous reports of changes in measured — SH groups thus appear to reflect solely changes in the reactivity of — SH groups and not in the total — SH groups present.Submitochondrial particles contained less than 0.5 nmole of apparent thiolester per mg of protein; mitochondria contained 1 to 2 nmoles. No variation of apparent thiolester content was noted with change in conditions affecting oxidative phosphorylation. The data do not, of course, eliminate possible changes in thiolester content below the sensitivity of the detection procedures.     

The semidian rhythm in flowering response of Pharbitis nil in relation to dark period time measurement and to a circadian rhythm

When seedlings of Pharbitis nil Choisy, cv. Violet, are exposed to a single inductive dark period at 27°C, brief interruptions with red light (R) can be promotive after 2–3 h of darkness but increasingly inhibitory to flowering up to the 8–9th h of darkness. This rhythmic response to R interruptions can be advanced in phase by > 1 h when the preceding light period is interrupted with far-red (FR) 2 h before darkness (FR -2 h) or with FR – 15 h, whereas FR –8 h or FR–22 h retard the rhythm. These shifts in the R interruption rhythm are paralleled by equal shifts in the length of the dark period required for flowering. Brief FR interruptions of darkness displayed a similar rhythm which was also advanced by FR –2 h and retarded by FR –8 h. We conclude therefore that the semidian rhythm in the light, which we have previously described, continues through at least the first 12 h of darkness, is manifested in the R interruption rhythm, and determines the critical night length. A circadian rhythm with a marked effect on flowering was also identified, but several lines of evidence suggest that the circadian and semidian rhythms have independent additive effects on flowering and do not appear to show phase interaction.     

Sequential passage of alpha2mu-globulin through the hepatic endoplasmic reticulum and Golgi apparatus during secretion.

Studies on the synthesis and secretion of the sex-dependent urinary protein, alpha2mu-globulin, have been extended by establishing its sequential passage from the rough to the smooth endoplasmic reticulum and Golgi-rich fractions of the liver of adult male rats. After injection of 14C-labeled amino acids, the maximum radioactivity of alpha2mu occurred at 20 min in the rough, 25 min in the smooth microsomes and 30 or 35 min in the Golgi-rich fractions. Radioactive alpha2mu-globulin appeared in the bloodstream and kidneys after a lag of 20--25 min. Results indicate that alpha2mu-globulin follows a secretory pathway similar to that of serum albumin.