Pigment protein complexes and functional properties of tetratype resulting from crosses between CP1 and CP2 less Chlamydomonas mutants

A chlorophyll b-less mutant of Chlamydomonas reinhardtii (Pg ₂₇) was isolated after UV irradiation of the wild type cells. This photosynthetically competent mutant totally lacks chlorophyll b and the CP₂ chlorophyll-protein complex. However, SDS-PAGE, proteolytic digestions and immunodetections demonstrated that the 24–25 Kd apoproteins of the lacking CP₂ complex are still present in thylakoids of the Pg₂₇ mutant. It is concluded that this CP₂-less mutant is affected in the biosynthesis pathway of chlorophyll b.This CP₂-less mutant was crossed with a CP₁-less mutant (Fl₅) Fluorescence emission spectra and fluorescence inductions in the presence of DCMU were analysed in the resulting (cp ₂ ^– , cp ₁ ⁺ ), (cp ₂ ⁺ , cp ₁ ^– ), (cp ₂ ⁺ , cp ₁ ⁺ ), cp ₂ ^– , cp ₁ ^– )tetratype. Differences in PS 2 optical cross section and in the relative amplitude or localisation of fluorescence emission peaks fit well with a quadripartite model where PS1 and PS2 would each correspond to a reaction centre core complex (CP₁ and CP₂ respectively) associated to a light harvesting antenna (LHC1 and LHC2 respectively). The occurrence of energy transfers from PS1 peripheral antenna to PS2 in the Fl ₅ mutant shows that, in absence of CP₁, at least a part of its associated PS1 light harvesting antenna migrates in the PS2 containing appressed thylakoids.Abbreviations Chl Chlorophyll - LHC Light harvesting chl a/b complex - CP₂ Predominant form of LHC or SDS polyacrylamide gels - WT Wild type - DM Double mutant (cp ₁ ^– , cp ₂ ^– ) - SDS-PAGE sodium dodecyl sulfate polyacrylamide gel electrophoresis - DOC-PAGE Deoxycholate polyacrylamide gel electrophoresis     

Accumulation of fructose 1,6-bisphosphate in mutant cells of mucoid Pseudomonas aeruginosa as an evidence of phosphofructokinase activity

Phosphoglucose isomerase negative mutant of mucoid Pseudomonas aeruginosa accumulated relatively higher concentration of fructose 1,6-bisphosphate (Fru-1,6-P₂) when mannitol induced cells were incubated with this sugar alcohol. Also the toluene-treated cells of fructose 1,6-bisphosphate aldolase negative mutant of this organism produced Fru-1,6-P₂ from fructose 6-phosphate in presence of ATP, but not from 6-phosphogluconate. The results together suggested the presence of an ATP-dependent fructose 6-phosphate kinase (EC 2.7.1.11) in mucoid P. aeruginosa.Abbreviations ALD Fru-1,6-P₂ aldolse - DHAP dihydroxyacetone phosphate - F6P fructose 6-phosphate - G6P glucose 6-phosphate - Gly3P glyceraldehyde 3-phosphate - KDPG 2-keto 3-deoxy 6-phosphogluconate - PFK fructose 6-phosphate kinase - PGI phosphoglucose isomerase - 6PG 6-phosphogluconate     

Enterotoxin A production in Staphylococcus aureus: inhibition by glucose

In this study, we investigated the relationship between carbohydrate metabolism and repression of staphylococcus enterotoxin A (SEA) in Staphylococcus aureus 196E and a pleiotrophic mutant derived from strain 196E. The mutant, designated at strain 196E-MA, lacked a functional phosphoenolpyruvate phosphotransferase system (PTS). The mutant produced acid, under aerobic conditions, from only glucose and glycerol. The parent strain contained an active PTS, and aerobically produced acid from a large number of carbohydrates. Prior growth in glucose led to repression of SEA synthesis in the parent strain; addition to the casamino acids enterotoxin production medium (CAS) led to more severe repression of toxin synthesis. The repression was not related to pH decreases produced by glucose metabolism. When S. aureus 196E was grown in the absence of glucose, there was inhibition of toxin production as glucose level was increased in CAS. The inhibition was related to pH decrease and was unlike the repression observed with glucose-grown strain 196E. The inhibition of SEA synthesis in mutant strain 196E-MA was approximately the same in cells grown with or without glucose and was pH related. Repression of SEA synthesis similar to that seen with glucose-grown S. aureus 196E could not be demonstrated in the mutant. In addition, glucose-grown S. aureus 196E neither synthesized -galactosidase nor showed respiratory activity with certain tricarboxylic acid (TCA) cycle compounds. Glucose-grown strain 196E-MA, however, did not show supressed respiration of TCA cycle compounds; -galactosidase was not synthesized because the mutant lacked a functional PTS. Cyclic adenosine-3, 5-monophosphate did not reverse the repression by glucose of SEA or -galactosidase synthesis in glucose-grown S. aureus 196E. An active PTS appears to be necessary to demonstrate glucose (catabolite) repression in S. aureus.Abbreviations SEA staphylococcal enterotoxin A - SEB staphylococcal enterotoxin B - SEC staphylococcal enterotoxin C - PTS phosphoenolpyruvate phosphotransferase system - CAS casamino acids salts medium - TCA tricarboxylic acid cycle     

Characteristics of structural proteins of infectious flacherie virus from the silkworm, Bombyx mori

Structural proteins and the characteristics of infectious flacherie virus (IFV) purified from the silkworm, Bombyx mori, are described. The purified IFV had four major structural proteins, which were detected only in high concentration gels of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and a few minor ones. Molecular weights of the major proteins were 35,200 (VP 1), 33,000 (VP 2), 31,200 (VP 3), and 11,600 (VP 4), and numbers per virion were 62, 57, 54, and 31, respectively. Amino acid compositions of VP 1, VP 2, and VP 3 were similar to each other but that of VP 4 was somewhat different. By isoelectric focusing and two-dimensional electrophoresis, high resolution of the structural proteins was obtained with silver staining. The isoelectric points of the four major proteins were determined as 7.7(VP 1), 6.7(VP 2), 4.8(VP 3), and 5.5(VP 4). This work is the first report on insect picornaviruses that presents some discriminative properties of each viral protein that was compared to those of mammalian picornaviruses.     

Micelle formation of diacylglycerophosphocholines in organic solvents I. effects of the solvents on krafft points

Krafft points of diacylglycerophosphocholines (PC) were measured in alkanes-cyclohexane solutions by differential scanning calorimetry, and it was found that they were regularly increased following the increase in alkane content in the solutions and the chain length of the alkanes. From these results it was deduced that the mixing of PC with alkanes occurred in the gel state of the PC, but not in micelles at higher temperatures above the Krafft points. where micellar solutions are provided. The penetration of alkanes into gel state PC was found to be dominated by Langmuir type interaction, and the affinity of alkanes increases with increasing in chain lengths. Above the Krafft points, the micelle formation was confirmed by using the fluorescence probe technique.     

Analysis of three-dimensional cell imaging obtained with optical microscopy techniques based on defocusing

The properties of an optical microscope are analyzed and analytically evaluated with a simple and effective model in order to understand the true meaning, limitations, and real capabilities of a defocusing technique. Major emphasis is given to the applications related to microscopic objects of biological interest using fluorescence and absorption light microscopy. A procedure for three-dimensional viewing is analyzed and discussed.     

PUC衍生质粒的一个低拷贝数突变型

本文报道大肠杆菌的ColE1类似质粒的一个低拷贝数突变型。从载体质粒pUC4衍生的重组质粒pPGVT3在大肠杆菌宿主DF2145中是不稳定的,以pPGVT3转化DF2145时在4o℃培养得不到转化子。用诱发点突变的羟胺体外处理pPGVF3质粒DNA,得到一个稳定性提高了的突变质粒pPGVT3HA,突变的位置被确定在质粒的pUC部分,突变降低了pUC及其衍生质粒的拷贝数。文中对质粒的稳定性与拷贝数的关系作了讨论。     

Interleukin-1 Hyperproduction by In Vitro Activated Peripheral Macrophages from Cerebellar Mutant Mice

Several mutations in mice produce complex patterns of neuronal degeneration of the cerebellum and of its afferent pathways. In the staggerer (sg/sg) mutant, atrophy of the lymphoid organs and immunological abnormalities have been described. To search for a possible link between the neurological and the immune disorders in this mutant, we studied the production by its peripheral macrophages of interleukin-1 (IL-1), which roles in both immune and nervous systems are well established. Suspensions of peritoneal and/or spleen macrophages from mutants and their appropriate controls were stimulated in vitro by lipopolysaccharide. Northern and dot blots, performed with murine IL-1 cDNA probes, revealed a clear-cut hyperexpression of IL-1 mRNA in staggerer macrophages. An IL-1 bioassay using the IL-1-responsive D10.G4 cell line also revealed a sixfold increase of IL-1 activity in the macrophage supernatants of staggerer mutant mice. The hyperproduction was found in 3-week to 1-year-old staggerer and also in heterozygous (+/sg) mice. A similar phenomenon existed in cerebellar mutants lurcher, Purkinje cell degeneration (pcd), and to a lesser extent reeler and wobbler, but was absent in the neurological mutants weaver, jimpy, and motor end plate disease (medH). These observations establish that in several point mutations in mice, central nervous degeneration is associated with dysregulation of IL-1 production by peripheral macrophages.     

Internode length and anatomical changes in Pisum genotypes crys and cryc in response to extended daylength and applied gibberellin A1

Dwarf pea (Pisum sativum L.) plants with genotypes cry^c and cry^s responded differently when an 8 h photoperiod (8 h daylight, 16 h dark) was extended to 24 h (8 h daylight, 16 h incandescent light). Genotype cry^c showed up to a 4-fold increase in internode length, sustained by increases in both cell length (particularly of epidermal cells) and cell number (particularly of cortical cells) while cry^s plants showed up to a 2-fold increase in internode length sustained mostly by an increase in cell number. Under an 8 h (daylight) photoperiod the two genotypes did not differ in their sensitivity to applied gibberellin A₁ (GA₁) and they showed a similar pattern of response. GA₁ significantly increased internode length, cell length and cell number in both genotypes. Incandescent light did not increase the size of the response to GA₁ except for cry^s plants at high dose rates of GA₁ (29–58 nmol). At saturating doses of GA₁ the two genotypes attained a similar peak internode length; incandescent light increased the peak by about 40%. GA₁ increased the rate of leaf appearance by up to 33% while incandescent light reduced the rate by 4–7%. The elongation response of the more mature internodes of cry^c plants to GA₁ or incandescent light was due primarily to an increase in cell length whereas increased cell number made a significant contribution in the case of internodes which were relatively immature at the time the stimulus was applied. The progressive increase in internode length of both genotypes during ontogeny was due primarily to an increase in cell number. In conclusion, alleles cry^c and cry^s (background le La) do not confer a difference in sensitivity to GA₁ and the increase in internode length in response to incandescent light is probably not the result of a real or perceived increase in GA₁ level. Allele cry^s may partially block a phytochrome mediated response to light and the key difference between genotypes cry^s and cry^c may lie in the greater elongation (extensibility?) of cry^c epidermal cells in incandescent light.