ABSTRACT
Observations are reported for Dysidea avara sponges where once functioning oscula (outlets) are converted through internal re-plumbing into functioning oversized ostia (OSO; inlets). Flow tank studies employed high-speed photography and particle tracking of laser-illuminated 0.5-6.0 microm diameter glass beads to trace particles streaming into OSO. A fluorescein dye/glass bead uptake experiment showed that an oversized ostium was connected through internal structures to the lone osculum. Beginning 30 s after uptake and continuing over a 20 min period, dye streamed from the osculum, but no beads emerged. Scanning electron microscopy revealed that beads were deposited only on the inhalant side of particle filtering choanocyte chambers and not on the exhalant side, suggesting that internal re-plumbing had occurred. Functioning OSO were also found on freshly collected specimens in the field, making it highly unlikely that formation of OSO was only an artefact of sponges being held in a laboratory tank.
Subject(s)
Dysidea/growth & development , Morphogenesis , Animals , Dysidea/anatomy & histology , Dysidea/physiology , Fluorescein/analysis , Glass , Microscopy, Electron, Scanning , MicrospheresABSTRACT
Mechanical load is an important factor in the differentiation of cells and tissues. To investigate the effects of increased mechanical load on development of muscle and bone, zebrafish were subjected to endurance swim training for 6 h/day for 10 wk starting at 14 days after fertilization. During the first 3 wk of training, trained fish showed transiently increased growth compared with untrained (control) fish. Increased expression of proliferating cell nuclear antigen suggests that this growth is realized in part through increased cell proliferation. Red and white axial muscle fiber diameter was not affected. Total cross-sectional area of red fibers, however, was increased. An improvement in aerobic muscle performance was supported by an increase in myoglobin expression. At the end of 10 wk of training, heart and axial muscle showed increased expression of the muscle growth factor myogenin and proliferating cell nuclear antigen, but there were major differences between cardiac and axial muscle. In axial muscle, expression of the "slow" types of myosin and troponin C was increased, together with expression of erythropoietin and myoglobin, which enhance oxygen transport, indicating a shift toward a slow aerobic phenotype. In contrast, the heart muscle shifts to a faster phenotype but does not become more aerobic. This suggests that endurance training differentially affects heart and axial muscle.
Subject(s)
Heart/growth & development , Heart/physiology , Muscle, Skeletal/growth & development , Muscle, Skeletal/physiology , Physical Endurance/physiology , Animals , Behavior, Animal/physiology , Body Size/physiology , Cell Division/genetics , Conditioning, Psychological/physiology , Energy Metabolism/genetics , Erythropoietin/genetics , Female , Gene Expression Profiling , Gene Expression Regulation, Developmental , Male , Muscle, Skeletal/cytology , Myocardium/cytology , Myoglobin/genetics , Oxygen/metabolism , Physical Conditioning, Animal/physiology , Swimming/physiology , Weight-Bearing/physiology , ZebrafishABSTRACT
Mouse antibodies to (2'-5')oligoadenylates were obtained by the immunization of animals with the (2'-5')oligoadenylic acid trimer conjugated with bovine serum albumin through a 2',3'-levulinic acid residue. Using radioimmunoassay, the reactivity of mouse polyclonal antibodies to the (2'-5')oligoadenylic acid trimer was studied for the trimer analogues containing 9-(3-deoxy-3-fluro-beta-D- xylofuranosyl)adenine and 3'-deoxy-3'-fluoro-adenosine in various positions of the chain. It was found that (a) the three-dimensional structure of short oligonucleotides is an important factor in the antibody recognition; (b) antibodies are more sensitive to modifications of the 5'-terminal and central ribose fragments of the (2'-5')oligoadenylic acid trimer; (c) the 3'-hydroxyl group plays a secondary role in the formation of the antigen determinant.
Subject(s)
Adenine Nucleotides/immunology , Antibodies/immunology , Oligoribonucleotides/immunology , Adenine Nucleotides/chemistry , Animals , Antibodies/chemistry , Biopolymers , Circular Dichroism , Mice , Oligoribonucleotides/chemistry , Serum Albumin, Bovine/immunology , StereoisomerismABSTRACT
The heterogeneity of the cyprinid fishes (about 2000 species) and their feeding requires a general model of aquatic feeding. In this model the timing of mouth and gill slit opening and the relative contribution of head expansion and swimming are determining factors. The following elements have been distinguished in the feeding process of cyprinid fishes: search/choice, intake (particulate intake and gulping), size-and taste selection, intra-oral transport (including repositioning), mastication and deglutition. The recognition of these processes is based on the combined use of X-ray, cine film, video and emg techniques. Structural specialisations, including the intra-oral density of sensory elements and their central connections with associated feed back loops, enable a wide variety of combinations and regulation of (stereotyped) motor patterns.
Subject(s)
Adaptation, Biological , Carps/physiology , Feeding Behavior/physiology , Animals , EatingABSTRACT
In recent years various examples of highly stable two-residue hairpin loops (miniloops) in DNA have been encountered. As the detailed structure and stability of miniloops appear to be determined not only by the nature and sequence of the two bases in the loop, but also by the closing base pair, it is desirable to carry out in-depth studies of especially designed small model DNA compounds. Therefore, a circular DNA dumbbell-like molecule is tailored to consist of a stem of three Watson-Crick base pairs, flanked on each side by a minihairpin loop. The resulting circular DNA decamer 5'-d
Subject(s)
DNA, Circular/chemistry , Nucleic Acid Conformation , Base Sequence , Kinetics , Molecular Sequence Data , ThermodynamicsABSTRACT
The conformational behavior of DNA minihairpin loops is sensitive to the directionality of the base pair that closes the loop. Especially tailored circular dumbbells, consisting of a stem of three Watson-Crick base pairs capped on each side with a minihairpin loop, serve as excellent model compounds by means of which deeper insight is gained into the relative stability and melting properties of hairpin loops that differ only in directionality of the closing pair: C-G vs G-C. For this reason the thermodynamic properties of the circular DNA decamers 5'-d
Subject(s)
DNA, Circular/chemistry , Nucleic Acid Conformation , Base Sequence , Chemical Phenomena , Chemistry, Physical , Molecular Sequence Data , ThermodynamicsABSTRACT
The circular DNA decamer 5'-d
Subject(s)
DNA, Circular/chemistry , Magnetic Resonance Spectroscopy , Models, Molecular , Nucleic Acid Conformation , ProtonsABSTRACT
A one- and two-dimensional NMR study has been performed on seven A(2'-5')A(2'-5')A fragments containing 9-(3'-fluoro-3'-deoxy-beta-D-xylofuranosyl)-adenine (AF) or 3'-fluoro-3'-deoxyadenosine (AF) residues at different positions, and on the corresponding monomers. A(2'-5')A(2'-5')A served as a reference compound. The fluoro substituent governs the conformation of the sugar ring: an AF residue displays mainly N-type sugar and the ring is considerably flattened (phi N approximately 30 degrees) compared to AF residues (phi S approximately 40 degrees), which exhibit almost pure S-type conformation. Moreover, in AF moieties the rotamer distribution around torsion angle gamma (O5'-C5'-C4'-C3') and the base orientation are influenced to a large extent by the presence of the fluorine substituent. The sugar rings of nonfluorinated residues in the trimers appear rather flexible. A possible correlation between the conformational characteristics of the fluorinated fragments and their biological activity has been found: the fragments that meet the prerequisites for binding to RNase L indeed show enhanced binding to this endonuclease. Furthermore, substitution of the 3'-OH group of the second residue by hydrogen or of the 3'-OH group of the 2'-terminal residue by fluorine or hydrogen results in increased resistance towards 2'-5'-phosphodiesterase.
Subject(s)
Adenine Nucleotides/chemistry , Deoxyadenosines/chemistry , Endoribonucleases/metabolism , Adenine Nucleotides/pharmacology , Deoxyadenosines/pharmacology , Magnetic Resonance Spectroscopy , Molecular Conformation , Polymers , Structure-Activity RelationshipABSTRACT
The naturally occurring RNA-nucleopeptide H-Ala-Tyr[5'-pUUAAAAC-3']-NH2 is prepared via a solid-phase phosphite triester approach using N-SiOMB/O-TBDMS-protected nucleosides. Preliminary 1H-NMR studies show that the peptidyl unit has a remarkable effect on the conformational behaviour of the RNA moiety in the nucleopeptide.
Subject(s)
Oligoribonucleotides/chemistry , Peptide Fragments/chemical synthesis , Poliovirus/chemistry , RNA, Viral/chemistry , Ribonucleoproteins/chemical synthesis , Viral Proteins/chemical synthesis , Magnetic Resonance Spectroscopy , Nucleic Acid Conformation , Nucleoproteins/chemistry , Peptide Fragments/chemistry , Ribonucleoproteins/chemistry , Viral Proteins/chemistryABSTRACT
The circular DNA decamer 5'-d [formula: see text] 3' is studied in solution by means of NMR spectroscopy. At low temperature the molecule adopts a dumbbell structure with three Watson-Crick C-G base pairs and two two-residue loops in opposite parts of the molecule. On raising the temperature another conformer appears, in which the closing C-G base pair in the 5'-GTTC-3' loop is disrupted, whereas the opposite 5'-CTTG-3' loop remains stable. The two conformers are in slow equilibrium over a limited temperature range.