Egg surface structure in the annual fishes Simpsonichthys (subgenera Ophthalmolebias and Xenurolebias) and Nematolebias (Teleostei: Cyprinodontiformes: Rivulidae): variability and phylogenetic significance

The surfaces of the egg chorion of nine species of Simpsonichthys , two of Nematolebias and eight other species of rivulids were studied with scanning electron microscopy revealing details of ornamentation that were previously undocumented. Surface structures of eggs of Simpsonichthys of the subgenus Ophthalmolebias are described for the first time: eggs of Simpsonichthys constanciae , Simpsonichthys perpendicularis , Simpsonichthys rosaceus and Simpsonichthys suzarti are ornamented with a very characteristic palm-like structure, that is restricted to these species among the rivulids examined. The surface of the egg chorion of Simpsonichthys bokermanni lacks the well-developed palm-like structure, but has a characteristic conical projection, distinct from the structures of other rivulids examined, that is proposed as homologous to the palm-like structure. Simpsonichthys bokermanni shares with Nematolebias papilliferus and Nematolebias whitei the presence of concentric rows of spiny projections around the micropylar region. Species of Simpsonichthys of the subgenus Ophthalmolebias , Simpsonichthys myersi (of the subgenus Xenurolebias ), and N. whitei share the presence of large rounded protuberances on the surface of the egg chorion. The phylogenetic significance of these features are evaluated and discussed in light of current knowledge about rivulid relationships.     

A study of the relationship between muscle length, tension-time area and stiffness in cat areflexic soleus

The relationship between muscle length and both tension-time area and stiffness were studied in the isolated cat soleus muscle during tetanic isometric contraction at different stimulus rates. The results show that: The area subtending the tension curve remains constant in a range of 8-10 mm of muscle length, for stimulation frequencies between 15 and 66 Hz. The muscle stiffness, measured using different amplitude stretches, remains constant over changes in muscle length of 10 mm. The stiffness is higher for smaller stretches than for larger ones. The data therefore show an approximately constant tension-time area and no significant changes in stiffness for variations in muscle length that exceed the physiological length variations during quiet standing. These results are discussed in the context of postural mechanisms.     

Thermal biology and locomotor performance of the Andean lizard Liolaemus fitzgeraldi (Liolaemidae) in Argentina

Ectotherms thermoregulate to maintain their body temperature within the optimal range needed for performing vital functions. The effect of climate change on lizards has been studied as regards the sensitivity of locomotor performance to environmental temperatures. We studied thermoregulatory efficiency and locomotor performance for Liolaemus fitzgeraldi in the Central Andes of Argentina. We determined body temperature, micro-environmental temperatures and operative temperatures in the field. In the laboratory, we measured preferred temperatures and calculated the index of thermoregulatory efficiency. We estimated the thermal sensitivity of locomotion by measuring sprint speed (initial velocity and long sprint) and endurance at five different body temperatures. Body temperature was not associated with either micro-environmental temperature, nor did it show differences with preferred temperatures. Thermoregulatory efficiency was moderate (0.61). Initial velocity and long sprint trials showed differences at different temperatures; however, endurance did not. Moreover, the optimal temperatures for the performance trials showed no significant differences among themselves. We conclude that Liolaemus fitzgeraldi has thermal sensitivity in locomotor performance with respect to body temperature and that it is an eurythermic lizard that experiences a large variation in body temperature and that has thermal flexibility in the cold.     

Cyclodextrins enhance the aerobic degradation and dechlorination of low-chlorinated biphenyls

Summary The aerobic dechlorination of 4-chlorobiphenyl and of Aroclor 1221 by Pseudomonas sp. CPE1 strain was enhanced by the presence of hydroxypropyl--cyclodextrin in the medium. The best dechlorination results were obtained when 4-chlorobiphenyl or Aroclor 1221 and the cyclodextrin were used at the molar ratios 1:1 and 1:1.5. This agent can be adopted to enhance the efficiency of PCB degradation tests.     

Papillomavirus capsid binding and uptake by cells from different tissues and species.

The inability of papillomaviruses (PV) to replicate in tissue culture cells has hampered the study of the PV life cycle. We investigated virus-cell interactions by the following two methods: (i) using purified bovine PV virions or human PV type 11 (HPV type 11) virus-like particles (VLP) to test the binding to eukaryotic cells and (ii) using different VLP-reporter plasmid complexes of HPV6b, HPV11 L1 or HPV11 L1/L2, and HPV16 L1 or HPV16 L1/L2 to study uptake of particles into different cell lines. Our studies showed that PV capsids bind to a broad range of cells in culture in a dose-dependent manner. Binding of PV capsids to cells can be blocked by pretreating the cells with the protease trypsin. Penetration of PV into cells was monitored by using complexes in which the purified PV capsids were physically linked to DNA containing the gene for beta-galactosidase driven by the human cytomegalovirus promoter. Expression of beta-galactosidase occurred in < 1% of the cells, and the efficiency of PV receptor-mediated gene delivery was greatly enhanced (up to 10 to 20% positive cells) by the use of a replication-defective adenovirus which promotes endosomal lysis. The data generated by this approach further confirmed the results obtained from the binding assays, showing that PV enter a wide range of cells and that these cells have all functions required for the uptake of PV. Binding and uptake of PV particles can be blocked by PV-specific antisera, and different PV particles compete for particle uptake. Our results suggest that the PV receptor is a conserved cell surface molecule(s) used by different PV and that the tropism of infection by different PV is controlled by events downstream of the initial binding and uptake.     

Effect of yeast extract on growth kinetics during aerobic biodegradation of chlorobenzoic acids

The Monod or Andrews kinetic parameters describing the growth of Pseudomonas sp. CPE2 strain on 2,5-dich!orobenzoic acid and 2-chlorobenzoic acid, and Al-caligenes sp. CPE3 strain on 3,4-dichlorobenzoic acid, 4-chlorobenzoic acid, and 3-chlorobenzoic acid were determined from batch and continuous growth experiments conducted in the presence or absence of yeast extract (50 mg/L). Strain CPE2 displayed inhibitory growth kinetics in the absence of yeast extract and a noninhibitory kinetics in the presence of yeast extract. Similar results were obtained for CPE3. The presence of yeast extract also resulted in a significant increase in the affinity of the strains for the chlorobenzoic acids they degraded. (c) 1995 John Wiley & Sons, Inc.     

Regulation by estrogen through the 5'-flanking region of the transforming growth factor alpha gene.

Expression of transforming growth factor alpha (TGF alpha) mRNA and protein can be stimulated by estrogens such as 17 beta-estradiol (E2) in estrogen-responsive rodent and human breast cancer cells. To ascertain if E2 can directly regulate TGF alpha expression through the 5'-flanking region of the human TGF alpha gene, E2-responsive MCF-7 or ZR-75-1 human breast cancer cells or E2-nonresponsive MDA-MB-231 breast cancer cells were transiently transfected with a plasmid containing an 1140-base pair (bp) Sac-I fragment of the TGF alpha 5'-flanking region ligated to the chloramphenicol acetyltransferase (CAT) gene. Cells that were transfected and subsequently treated with physiological concentrations of E2 (10(-11)-10(-8) M) for 24 h exhibited a 2- to 10-fold increase in CAT activity. The E2 stimulation of CAT activity was dose-dependent with an increase first found at 10(-10) M E2. The increase in CAT activity could be detected within 24-36 h after the addition of E2. There was no significant change in CAT activity in transiently transfected MDA-MB-231 cells as mediated through the TGF alpha 5'-flanking region after E2 treatment. MCF-7 cells were also transiently transfected with different fragments of the TGF alpha 5'-flanking region ligated to the luciferase gene. In the absence of E2 treatment, no detectable luciferase activity was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Improved high-affinity binding of 3H-apomorphine with a subcellular membrane fraction of mammalian brain tissue

The binding of low concentrations of [³H](?)apomorphine to preparations of calf and rat forebrain tissue was evaluated. Fractionation of crude homogenates to prepare a membrane fraction (P₄) of striatal or caudate homogenates increased the proportion of saturable to total binding from 33% to over 80%, and increased the apparent density of binding sites from 94 to 681 fmol/mg protein. Binding in calf caudate P₄ tissue was protein-dependent and optimal at pH = 7.0 to 7.5, and T = 20 to 25°C; at higher temperatures tissue binding sites appeared to degrade. The half-time of association and dissociation at 22°C were, respectively, 14.0 and 18.5 min; equilibration was complete in 60 min. Kinetic characteristics of high-affinity binding obtained from association and dissociation constants and from saturation isotherms were similar (K_d = 2.1 to 3.4 nM). The pharmacology of competition for ³H-APO suggests selectivity for dopamine-agonist interactions. These results indicate that the P₄ membrane preparation may be useful for the evaluation of dopamine-agonist binding sites or “receptors.”     

SERS‐based biosensor for Alzheimer disease evaluation through the fast analysis of human serum

Alzheimer disease (AD) is the most common form of dementia in the elderly, progressively affecting the cognitive functions with a complex diagnostic procedure that limits the time for a prompt intervention. In this study we optimized a reliable protocol for the analysis of AD patients and healthy subjects' serum using the Surface Enhanced Raman Spectroscopy (SERS), taking into consideration the effect of different variables on the final spectra, analyzed and compared through multivariate analysis and correlated with hippocampus volume. As results, we demonstrated a statistical difference between the spectra collected from the two investigated groups, with an accuracy, precision and specificity of respectively 83%, 86%, and 86%. The correlation of these data with those obtained from MRI, demonstrated a direct correlation between Raman spectra and hippocampus degeneration showing the Raman Spectroscopy (RS) as a potential tool for the monitoring of AD progression and rehabilitation treatments.