Structure and sensory apparatus of oral remnants of the nasopalatine canals in the fin whale (Balaenoptera physalus L.)

Light microscopy of serially sectioned nasopalatine duct remnants in ventral rostral integument of four adult (2 ♂, 2 ♀) fin whales reveals: (1) a common structure in all, (2) blindly ending nasopalatine pits 4 to 9 mm deep, (3) solid epithelial duct remnants 12 to 15 mm long, (4) lack of chemoreceptor endings, and (5) an abundance of presumed mechanoreceptors, mostly of the Pacinian category on the adoral sides, but also including some thinly encapsulated and perivascular ones that extend into the abundant connective tissue papillae of the duct remnants. Comparative and evolutionary relations of these structures are discussed.     

Comparison of methods for extracting intracellular pools of inorganic nitrogen from marine phytoplankton

Marine phytoplankton can accumulate large intracellular poolsof nitrate and ammonium under some growth conditions. A numberof different methods have been used to extract these pools whichdiffer primarily in the way the cells are broken to releasethe pools. In this study, seven methods of extracting nitrateand ammonium pools were examined in four species of marine phytoplanktongrown so that extraction of both large and small pools couldbe tested. The methods of breaking cells examined included variouscombinations of osmotic shock, heat treatment, grinding, sonication,and freeze–thawing. Of these, two methods which use osmoticshock or osmotic shock combined with heating, yielded the highestpool concentrations, the best percent recoveries, and the leastvariability. Osmotic shock combined with heat is the recommendedextraction procedure since it may be more effective with cellswhich are difficult to break. ¹Current address: Bigelow Laboratory for Ocean Sciences, MckownPoint, West Boothbay, Maine 04575, USA     

A brief review of lyophilization damage and repair in bacterial preparations

The principal concern of those responsible for the maintenance of culture collections has been to preserve viability, but nonlethal damage should not be ignored. Whether disruption of any element of a cell is nonlethal depends on the ability of the cell to repair the damage. Subsequent repair of DNA damage can lead to mutation.The protective effect of additives, as measured by survival after lyophilized cultures are reconstituted, sometimes depends upon the interval between making the addition and freezing. A rhythmic variation in the extent of viability has been observed, but increases in number of viable cells cannot be attributed to a repair mechanism. Instead, the changes in survival appear to be associated with a physiological condition of the cell at the instant of freezing.Virulence is generally maintained by lyophilized bacteria, but when stored cultures of Y. pestis were assayed immediately after reconstitution, virulence for mice was significantly reduced (as many as 4000 cells per 50% lethal dose). The virulence could be fully restored by holding reconstituted cultures for 24 hr at room temperature, or by subculture in fresh media. Obviously, the injury induced by lyophilization and storage is not to the DNA.     

Conversion of 2,4,6-trinitrophenol to a mutagen by Pseudomonas aeruginosa.

A strain of Pseudomonas aeruginosa reduced 2,4,6-trinitrophenol (picric acid) to 2-amino-4,6-dinitrophenol (picramic acid) under anaerobic conditions. Mutagenic assays of picric acid and picramic acid were carried out with histidine-requiring strains of Salmonella typhimurium. Picric acid (10 micrograms per plate) demonstrated mutagenicity (both frame shift and base substitution-gype mutations) only after activation with a rat liver homogenate preparation. Picramic acid (1 microgram per plate) induced both base pair substitution and frame shift-tupe mutations without activation by the rat liver preparation.     

Quantitative characteristics of the Feyrter cells and neuroepithelial bodies of the fetal rabbit lung in normoxia and short term chronic hypoxia

We report here quantitative data on the Feyrter (single) cells (APUD cells) and neuroepithelial bodies (grouped Feyrter cells), in the lungs of rabbit fetuses at 26, 27.5 and 29 days gestational age, during normoxia and short term chronic hypoxia. The apparent number of these cells declines during this period; we suggest that this might be due to increased hypoxemia. Moreover, the number of cells in the lungs of fetuses from short term chronically hypoxic mothers is lower than in the normoxic animals. These findings are in agreement with our previous studies in short term chronically hypoxic neonatal rabbits, and suggest that the increased hypoxemia in the fetus, caused by the induction of hypoxia in the mother, constitutes a stimulus for secretory activity of the Feyrter cells and neuroepithelial bodies (NEBs). This in turn could be part of the mechanism responsible for maintaining the pulmonary vasoconstriction due to hypoxemia. Our results from fetuses of normoxic does provide base line data on the chronological importance of the Feyrter cells and NEBs.