Effects of chloride ion on HILL reactions in Euglena chloroplasts

Effects of Cl^– and other anions on the rate of HILL reactionin Euglena chloroplasts were investigated. Cl^– acceleratedthe reaction rate with ferricyanide as HILL oxidant; Br^–,F^– and I^– were also effective; NO₃^–, PO₄^2–and SO₄^2– were less effective. Divalent cations, Ca²⁺and Mg²⁺, were also highly effective. The promoting effectsof these ions were highly dependent on pH and the nature andconcentration of the HILL oxidant used. Accelerating effectsof the ion increased with decreasing concentrations of ferricyanide.Generally, the stimulating effect of Cl^– was much moremarked at pH 7–7.5, with little effect at pH 5. Thus,the pH-activity relationship in the HILL reaction is more orless markedly modified by addition of ions. Cl^–, and other anions, accelerated the reaction by affectingonly the dark rate-limiting portion of the HILL reaction; thelight reaction constant remained uninfluenced. We inferred thatsome reaction step, at which ferricyanide receives electronfrom photosystem 2, is accelerated by Cl^– and other ions.Cl^– effects were rather small, or undetectable, with DPIPor p-benzoquinone as oxidants. (Received January 8, 1970; )     

Primers Designed for Amplification of Echinococcus multilocularis DNA Amplify the DNA of Encephalitozoon-Like Spores in the Polymerase Chain Reaction

ABSTRACT. Microsporidian spores were developed from cells which were grown in vitro from a human liver lesion which was due to larval Echinococcus multilocularis . The microsporidian spores developed in the same fashion as an Encephalitozoon cuniculi . The Encephalitozoon -like spores were completely separated on Percoll gradients. The separated spores contained DNA capable of amplification by two different primer sets designed for the polymerase chain reaction (PCR) of E. multilocularis DNA. However, the cell DNA from which microsporidium developed was thoroughly insensitive to the PCR using the E. multilocularis primer sets. The results strongly suggested that Encephalitozoon should be taken into consideration, when DNA isolated from larval E. multilocularis is analyzed.     

'METACHRONOUS' CLEAVAGE AND INITIATION OF GASTRULATION IN AMPHIBIAN EMBRYOS

The cleavage pattern in the egg of Xenopus laevis has been investigated with the aid of time-lapse cinematography. From the 5th cleavage onward, divisions of the surface blastomeres are not synchronous but metachronous. A few blastomeres in a very restricted region which is situated in most cases in the dorsal side of the animal hemisphere, slightly distant from the median line and near the equatorial junction of the animal and vegetal hemispheres, divide before the other blastomeres, and a wave-like propagation of the divisions travels along the surface from that region toward the animal and vegetal poles. The wave-like propagation ends in the vegetal pole region. In the animal hemisphere, this pattern of cleavage is continued until the 13th cleavage and thereafter the divisions of surface blastomeres become asynchronous. In the vegetal pole region, however, the 14th metachronous division of blastomeres is clearly observed in the film. Gastrulation begins after 14 cleavages.     

Protein Synthesis in Dormant and Non-Dormant Cocklebur Seed Segments

Using the axial and cotyledonary segments of lower cocklebur (Xanthium pensylvanicum Wallr.) seeds, protein synthesis as shown by incorporation of radioactive leucine was examined in relation to their dormant status. During the first 9 h of water imbibition, the protein synthesis was higher in the dormant axes than in the non-dormant, after- ripened ones. When imbibed for more than 12 h non-dormant axes had a higher activity than dormant ones. This was also the case with the cotyledonary segments. Cyctoheximide, an inhibitor of protein synthesis, blocked protein synthesis in the axial tissue regardless of its dormant status, and thereby inhibited germination of the non-dormant seeds. In the dormant seeds, however, cycloheximide at 3 mM slightly stimulated germination without stimulating the C₂H₄ production. Based on these results, it is suggested that in cocklebur seeds there may be some proteinaceous system which is involved in the maintenance of dormancy.     

Changes in Photosynthetic Activity and Related Processes Following Decapitation in Mulberry Trees

Physiological responses to decapitation, in combination with bud removal or bud retention, were followed for 45 days in mature leaves of potted mulberry trees (single shoot with 24 to 28 leaves) held in a greenhouse. Mature leaves, whose photosynthetic activity had already attained a maximum, initially increased and subsequently maintained their rates of gas exchange after decapitation. Equivalent leaves on intact trees showed a gradual decline in photosynthesis together with other changes generally associated with early senescence viz. loss of chlorophyll, increased starch, and accumulation of one category of cytokinin-like material presumed to be a glucose ester. Maintenance of physiological activity following decapitation, especially when combined with bud removal, was associated with greater chlorophyll content, mesophyll cell enlargement (palisade cells appeared more elongate), lower starch, and alteration in foliar levels of cytokinin-like substances. Internal constraints on CO₂ assimilation, i.e. residual resistance (rr), rather than stomatal factors, appeared to be the major influence on gas exchange. The higher photosynthetic activity of leaves on decapitated trees relative to control trees of the same age was attributed to lower r, but was also associated with higher chlorophyll content (leaf area basis) so that CO₂ assimilated per unit chlorophyll was not substantially altered by treatment.     

No contribution of the pentose phosphate pathway in dormancy-breaking of cocklebur seeds

The role of the oxidative pentose phosphate (PP) pathway in the dormancy-breaking of cocklebur (Xanthium pennsylvanicum Wallr.) seeds was investigated. D-[1-¹⁴C]-glucose or D-[6-¹⁴C]-glucose was fed to dormant and non-dormant lower seeds or to their axial or cotyledonary segments which were imbibed for different durations, and C₆/C₁ ratios of respired ¹⁴CO₂ as an index of the PP pathway activity were calculated. Contrary to expectation, there was no significant difference in the C₆/C₁ ratios between the dormant and non-dormant seeds or segments during a water imbition period of 24 h, although the PP pathway actually operated already in an early stage of water imbibition. Also concerning the activities of G6PDH and 6PGDH, the key enzymes of this pathway, no difference between the dormant and non-dormant seeds was found. It was thus concluded that, unlike other seeds, there is no contribution of the PP pathway to the regulation of dormancy of the cocklebur seed.     

The phylogenetic position of toadfishes (order Batrachoidiformes) in the higher ray-finned fish as inferred from partitioned Bayesian analysis of 102 whole mitochondrial genome sequences

In a previous study based on 100 whole mitochondrial genome (mitogenome) sequences, we sought to provide a new perspective on the ordinal relationships of higher ray-finned fish (Actinopterygii). The study left unexplored the phylogenetic position of toadfishes (order Batrachoidiformes), as data were unavailable owing to technical difficulties. In the present study, we successfully determined mitogenomic sequences for two toadfish species ( Batrachomoeus trispinosus and Porichthys myriaster ) and found that the difficulties resulted from unusual gene arrangements and associated repetitive non-coding sequences. Unambiguously aligned, concatenated mitogenomic sequences (13 461 bp) from 102 higher actinopterygians (excluding the ND6 gene and control region) were divided into five partitions (1st, 2nd and 3rd codon positions of the protein-coding genes, tRNA genes and rRNA genes) and partitioned Bayesian analyses were conducted. The resultant phylogenies strongly suggest that the toadfishes are not members of relatively primitive higher actinopterygians (Paracanthopterygii), but belong to a crown group of actinopterygians (Percomorpha), as was demonstrated for ophidiiform eels (Ophidiiformes) and anglerfishes (Lophiiformes) in the previous study. We propose revised limits of major unranked categories for higher actinopterygians and a new name (Berycomorpha) for a clade comprising two reciprocally paraphyletic orders (Beryciformes and Stephanoberyciformes) based on the present mitogenomic phylogenies.  © 2005 The Linnean Society of London, Biological Journal of the Linnean Society , 2005, 85 , 289–306.     

Seed Storage Glutelin α-2 Subunit Lacking Mutants in Rice

Nine rice Oryza sativa L.） mutant lines lacking the seed storage glutelin α-2 subunit were obtained from the progenies of fertilized egg cells treated with N-methy-N-nitrosourea (MNU). The mutants could be classified into three types: the α-1 subunit increased type (α-1H/α-2L), decreased the β-2 subunit decreased type (β-2L/α-2L) and the α-3 subunit increased type (α-3H/α-2L) according to their SDS-PAGE profiles. Two-dimensional electrophoresis analysis revealed that all of the mutants lacked a polypeptide of pI 6.71/α-2, while new polypeptides of pI 6.50/α-1 and pI 6.90/α-3 formed in α-1H/α-2L and α-3H/α-2L mutants respectively. Although the β-2L/α-2L mutants did not form new polypeptide, their pI 8.74/β-2 polypeptide was also decreased, suggesting that the two polypeptides decreased in β-2L/α-2L mutants might derive from the same glutelin precursor. These mutant lines are very useful in studying genetic characterisation,the mechanism of genetic regulation on biosynthesis, gene function and proteomics of rice seed storage glutelin.     

UV reflectance of inter-subspecific hybrid females obtained by crossing cabbage butterflies from Japan (Pieris rapae crucivora) with those from New Zealand (P. rapae rapae)

Cross-mating was performed between subspecies of cabbage butterfly Pieris rapae crucivora from Japan and P. rapae rapae from New Zealand, whose females are known to reflect and absorb ultraviolet (UV) light, respectively. In the female F ₁ hybrids UV reflectance was intermediate between the two parent females. Further, the UV reflectance was significantly higher in the female F ₁ hybrids derived from females of the New Zealand subspecies than in those derived from females of the Japanese subspecies.