The self-incompatibility phenotype in brassica is altered by the transformation of a mutant S locus receptor kinase

The self-incompatible (SI) Brassica napus line W1, which carries the 910 S allele, was transformed with an inactive copy of the 910 S locus receptor kinase (SRK) gene. Two transformed lines were analyzed based on their heritable ability to set self-seed. The first line was virtually completely self-compatible (SC), and reciprocal pollinations with the original W1 line demonstrated that only the stigma side of the SI phenotype was altered. An analysis of the expression of endogenous SRK-910 demonstrated that the mechanism of transgene action is via gene suppression. Furthermore, the expression of the S locus glycoprotein gene present in the 910 allele (SLG-910), SLG-A10, which is derived from a nonfunctional S allele, and an S locus-related gene were also suppressed. When the transgene was crossed into another SI line carrying the A14 S allele, it was also capable of suppressing the expression of the endogenous genes and of making this line SC. The second transgenic line studied was only partly SC. In this case as well, only the stigma phenotype was affected, although no gene suppression was detected for endogenous SRK-910 or SLG-910. In this line, the expression of the transgene most likely was causing the change in phenotype, and no effect was observed when this transgene was crossed into the other SI line. Therefore, this work reinforces the hypothesis that the SRK gene is required, but only for the stigma side of the SI phenotype, and that a single transgene can alter the SI phenotype of more than one S allele.     

Pulmonary Changes in Lung Purpura and Some of the Other Collagen Diseases

The physician who specializes in pulmonary diseases has a most helpful aid in the form of chest roentgenography. This examination is secured routinely in many hospitals and clinics today. The roentgenogram is very accurate in finding pulmonary lesions. Accuracy in determining the type of lesion depends on the experience of the physician who is studying the patient.Pulmonary lesions occur in many systemic diseases. They may occur in some of the collagen diseases and at times they may be the first and also the most striking findings noted during the examination of a patient. For this reason, attention is called to some of the pulmonary findings encountered in certain of these diseases. Some of the clinical, roentgenologic and pathologic manifestations of necrotizing alveolitis, periarteritis nodosa, glomerulonephritis, disseminated lupus erythematosus, rheumatoid arthritis, and scleroderma are described.     

A method for aligning RNA secondary structures and its application to RNA motif detection

Background  

Alignment of RNA secondary structures is important in studying functional RNA motifs. In recent years, much progress has been made in RNA motif finding and structure alignment. However, existing tools either require a large number of prealigned structures or suffer from high time complexities. This makes it difficult for the tools to process RNAs whose prealigned structures are unavailable or process very large RNA structure databases.     

Comparative benthic plant ecology by SCUBA-monitored quadrats

The feasibility of permanent benthic quadrats checked by SCUBA divers was tested. Stations were set up on the bottom of six representative aquatic habitats, both marine and inland, including oligotrophic and eutrophic ponds, river, coastal lagoon, estuary, and open marine coast. Data include physical-chemical factors, species composition, number and height of shoots, and general observations. From volume/length constants, the standing crops per quadrat were calculated. Seasonal changes in environmental factors and plant standing crop are parallel-plotted for the six habitats, thus providing comparative information on stations. Benthic diel periodicity and light intensity periodicity at various depths were investigated also. In all habitats, maximum standing crop occurred in July and August, but species composition varied considerably. Length of time the water temperature exceeded 15C did not correlate with standing crop. Dissolved oxygen was never deficient, even under ice; and diurnal changes were slight. Light was diminished under ice, but 4–60 ft-c were recorded in midwinter. Lenght of day is about 2 hours shorter at 20 ft than at 6 ft. Onset of vernal benthic growth seems correlated more closely with increase in light intensity than with temperature. The permanent quadrats monitored by divers proved feasible in all habitats tested, and directly comparable data were obtained.Supported in part by a grant from the National Science Foundation.     

The life history of Pyramimonas amylifera Conrad (Prasinophyceae)

Several possible life history stages of a clone of Pyramimonasamylifera Conrad (Prasinophyceae) have been encountered in culturestudies. These include: 1) octoflagellates; 2) cysts; 3) quadriflagellates;4) biflagellates; and 5) multilobate cells with each lobe bearingeight flagella. The octoflagellates have the ultra-structuralcharacteristics previously documented for P. amylifera. Scanningelectron microscopy was used to examine surfaces of cysts andbiflagellates. Scales of the type which form the middle (basket-shaped)and outer (coronate) scale layers on the octoflagellate wereobserved on the surface of cysts. Scales of the type which formthe middle body layer on octoflagellates were observed on thebodies of biflagellates. Biflagellates, quadriflagellates, andempty cysts were observed in several cultures which had beensubjected to a 5-week dark incubation before return to a low-lightregime. In one of those cultures, a single cyst containing motileswarmers was observed. The biflagellates or quadriflagellatesmay represent cyst-germination products. ^*Present address: Department of Biology, University of SouthFlorida, Tampa, Florida, U.S.A. 33620.     

Tintinnid agglutination of coccoliths: A selective or random process?

This study suggests that tintinnids are not strongly selective when agglutinating coccoliths from their environment. If selectivity does occur it may be due to the possibility that tintinnids exclude, for their loricae building, coccoliths above a certain size limit.     

Seasonal variations of tintinnids (Ciliophora: Oligotrichida) in Narragansett Bay, Rhode Island, U.S.A.

Tintinnids exhibit a bimodal peak of abundance in NarragansettBay, with a minimum in late spring and a lesser peak in latesummer-early autumn, depending on location. Thirty-three speciesin eight genera were identified, with the fauna dominated bythe genus Tintinnopsis. Tintinnid abundance was not obviouslycorrelated with salinity, temperature, or nanoplankton chlorophyllconcentration. Patterns of change in seasonal abundance canserve as a framework for posing additional questions of therole tintinnids play in marine food webs.     

Olfactory memory: the long and short of it

It has been proposed that memory for odors does not have a short-term (or working) memory system. The distinction between short- and long- term memory in other sensory modalities has been generally supported by three main lines of evidence: capacity differences between the proposed systems, evidence of differential coding, and differential memory losses in neuropsychological patients. The present paper examines these issues in an effort to establish a similar distinction for the memory of olfactory stimuli. Each of these lines of evidence is examined in relation to the literature on olfactory memory. Based on this examination, it seems that there is at least preliminary support from each of these lines of evidence to advocate a distinction between a long- and short-term memory for olfactory stimuli. Emphasis is placed upon the qualitative similarity of olfactory memory to other memory systems. This similarity is further highlighted through an examination of the literature pertinent to serial position effects in memory for olfactory stimuli.      

STUDIES ON MARINE PLANKTON DIATOMS. II. RESTING SPORE MORPHOLOGY1

A morphological study of resting spores in five marine planktonic diatom species using electron microscopy indicates that Bacteriastrum delicatulum Cleve and Leptocylindrus danicus Cleve spores bear little resemblance, to their vegetative cells. Detonula confervacea (Cleve) Gran and Stephanopyxis turris (Grev. & Arn.) Ralfs spores have several features in common with their vegetative cells, and Rhizosolenia setigera Brightwell lies between the two extremes. The function of resting spores in relation to diatom life cycles is briefly discussed. Spore formation may be a primitive characteristic in the life cycle and may no longer have significant survival value for the species.