An analysis of the inactivation of the frog sperm nucleus by toluidine blue

Toluidine blue, applied to frog sperm under appropriate conditions, inactivates specifically the sperm nucleus, leaving the extranuclear parts of the cell undamaged. Thus, the dye-treated spermatozoa stimulate eggs to cleave normally, but contribute no chromosomes to the resulting embryos, which develop as typical gynogenetic haploids. The concentration of dye required to produce this inactivation varies with pH. Measurements made over the entire pH range which can be tolerated by sperm cells showed that in the lower part of the range (5 to 7) the effective dye concentration was about 5 x 10(-6)M; in the intermediate range (7 to 8.5) it was 1 x (-6) to 1 x (-7)M; and for the higher pH values (8.5 to 10.0) it was about 5 x (-8)M. Using sperm suspensions containing 1500 cells per c. mm. these concentrations of dye produced specific inactivation of the sperm nuclei within 7 to 60 minutes at 18 degrees C. Tests of the reversibility of the inactivation were made by transferring the sperm from the dye to a dilute Ringer's solution after a known degree of inactivation had been produced. Following removal of the dye the sperm cells were tested on eggs over a period of 2 hours. During this time there was no indication of a reversal of the inactivation. Microscopic observations of sperm treated with (-5)M or 5 X (-5)M dye show that the dye is taken up by the sperm nucleus, which is faintly but definitely stained. The dye appears to be uniformly distributed in the nucleus, while extranuclear structures remain unstained. Measurements of the amount of dye bound per sperm nucleus indicate that the minimal quantity required for complete inactivation is about 6.7 x (-18) mole, while the maximal amount which can be bound without injury to extranuclear structures is about 1.5 x (-16) mole. The value obtained for the minimal requirement (6.7 X (16) mole = 4 X (6) molecules) suggests that there are roughly 4 million binding sites in the nucleus which, when blocked by dye molecules, somehow prevent the sperm chromosomes from participating in the development of the egg.     

Isolation and1H-NMR spectroscopic identification of the glucose-containing lipid-linked precursor oligosaccharide ofN-linked carbohydrate chains

The lipid-linked precursor ofN-type glycoprotein oligosaccharides was isolated from porcine thyroid microsomes after in cubation with UDP[³H] Glucose. The carbohydrate was released from dolichol pyrophosphate by mild acid hydrolysis, purified by gel filtration and characterized by 500-MHz¹H-NMR spectroscopy in combination with enzymatic degradation. The parent oligosaccharide was found to be Glc₃Man₉Glc-NAc₂. The three glucose residues are present in the linear sequence Glcα1-2Glα1-3 Glc, the latter being α(1-3)-linked to one of the mannose residues. In order to establish the branch location of the triglucosyl unit, the parent compound was digested with jack-bean α-mannosidase. The oligosaccharide product was purified by gel filtration, and identified by¹H-NMR as Glc₃Man₅GlcNAc₂ lacking the mannose residues A, D₂, B and D₃. Therefore, the structure of the precursor oligosaccharide is as follows: $$\begin{gathered} c b a D_1 C 4 \hfill \\ Glc\alpha 1 - 2Glc\alpha 1 - 3Glc\alpha 1 - 3Man\alpha 1 - 2Man\alpha 1 - 2Man\alpha 1 \hfill \\ 3 \swarrow 3 2 1 \hfill \\ Man\alpha 1 - 2Man\alpha 1 Man\beta 1 - 4GlcNAc\beta 1 - 4GlcNAc \hfill \\ D_{2 } A 3 6 \hfill \\ Man\alpha 1 \hfill \\ 6 \hfill \\ Man\alpha 1 - 2Man\alpha 1 \nwarrow 4 \hfill \\ D_3 B \hfill \\ \end{gathered} $$      

The photoperceptive sites and the function of tissue light-piping in photomorphogenesis of etiolated oat seedlings*

Abstract. Responses to red light irradiation of discrete areas along the intact, etiolated oat seedling indicate that illumination of the region around the coleoptilar node results in maximal coleoptile growth stimulation and mesocotyl growth suppression. Quantitation of the fibre optic properties of these etiolated tissues shows that the amount of axially transmitted light is log linear as a function of distance for both the mesocotyl and coleoptile (plus primary leaf). Using the fibre optic properties of the tissues to predict the response of the etiolated seedling to defined illumination fields allows one to localize two sites of photoperception: although the mesocotyl response pattern can be explained by the action of a single site found near the top of the mesocotyl itself, the coleoptile response depends on irradiation of both the mesocotyl site and an additional site located just above the node. The very low- and the low-fluence responses of etiolated oats independently predict similar regions of the seedling as sites of photo-perception. The fibre optic properties of the seedling could allow the seedling to increase the effective light signal received by the photosensitive area significantly.     

Increased expression of costimulatory markers CD134 and CD80 on interleukin-17 producing T cells in patients with systemic lupus erythematosus

Introduction  

There is growing evidence that interleukin 17 (IL-17) producing T cells are involved in the pathogenesis of systemic lupus erythematosus (SLE). Previous studies showed that increased percentages of T-cell subsets expressing the costimulatory molecules CD80 and CD134 are associated with disease activity and renal involvement in SLE. The aim of this study was to investigate the distribution and phenotypical characteristics of IL-17 producing T-cells in SLE, in particular in patients with lupus nephritis, with emphasis on the expression of CD80 and CD134.     

Baseline predictors of response and discontinuation of tumor necrosis factor-alpha blocking therapy in ankylosing spondylitis: a prospective longitudinal observational cohort study

Introduction  

Identifying ankylosing spondylitis (AS) patients who are likely to benefit from tumor necrosis factor-alpha (TNF-α) blocking therapy is important, especially in view of the costs and potential side effects of these agents. Recently, the AS Disease Activity Score (ASDAS) has been developed to assess both subjective and objective aspects of AS disease activity. However, data about the predictive value of the ASDAS with respect to clinical response to TNF-α blocking therapy are lacking. The aim of the present study was to identify baseline predictors of response and discontinuation of TNF-α blocking therapy in AS patients in daily clinical practice.     

Advanced glycation endproducts are increased in rheumatoid arthritis patients with controlled disease

Introduction  

Advanced glycation end products (AGEs) are produced and can accumulate during chronic inflammation, as might be present in patients with rheumatoid arthritis (RA). AGEs are involved in the development of cardiovascular disease. The aim of this study is to evaluate whether AGEs are increased in patients with long-standing RA and whether AGE accumulation is related to disease activity, disease severity and measures of (premature) atherosclerosis, such as endothelial activation, endothelial dysfunction and intima media thickness (IMT).     

Expression of collier in the premandibular segment of myriapods: support for the traditional Atelocerata concept or a case of convergence?

Background  

A recent study on expression and function of the ortholog of the Drosophila collier (col) gene in various arthropods including insects, crustaceans and chelicerates suggested a de novo function of col in the development of the appendage-less intercalary segment of insects. However, this assumption was made on the background of the now widely-accepted Pancrustacea hypothesis that hexapods represent an in-group of the crustaceans. It was therefore assumed that the expression of col in myriapods would reflect the ancestral state like in crustaceans and chelicerates, i.e. absence from the premandibular/intercalary segment and hence no function in its formation.