Sex-specific somatic–otolith growth relationship in two Gadidae

Otolith and somatic mass of two Gadidae ( Merlangius merlangus and Trisopterus minutus ) were compared in order to analyse the sex-specific relationship between otolith and somatic growth at age. In the present study, otolith mass appeared a reliable indicator of age in both species. Otolith growth reflected somatic growth, but the relationship between these characters varied and differed between species and sexes.     

Biodeterioration of Mayan buildings at uxmal and tulum,Mexico

Uxmal and Tulum are two important Mayan sites in the Yucatan peninsula. The buildings are mainly composed of limestone and grey/black discoloration is seen on exposed walls and copious greenish biofilms on inner walls. The principal microorganisms detected on interior walls at both Uxmal and Tulum were cyanobacteria; heterotrophic bacteria and filamentous fungi were also present. A dark‐pigmented mitosporic fungus and Bacillus cereus, both isolated from Uxmal, were shown to be acidogenic in laboratory cultures. Cyanobacteria belonging to rock‐degrading genera Synechocystis and Gloeocapsa were identified at both sites. Surface analysis previously showed that calcium ions were present in the biofilms on buildings at Uxmal and Tulum, suggesting the deposition of biosolubilized stone. Apart from their potential to degrade the substrate, the coccoid cyanobacteria supply organic nutrients for bacteria and fungi, which can produce organic acids, further increasing stone degradation.     

Molecular systematics of the Atlanto-Mediterranean Solea species

Within the genus Solea , four sister lineages have been evolved that actually correspond to the species S. vulgaris, S. senegalensis, S. kleini and S. lascaris . The existence of S. aegyptiaca and S. impar is not supported and these species can be synonymized under S. vulgaris and S. lascaris , respectively. This pattern of taxonomy agrees fully with that proposed by Ben-Tuvia (1990; Journal of Fish Biology 36, 947–960) based on morphological features. In addition, mtDNA data contradict the widely accepted relatedness between S. kleini and S. lascaris based on the shared enlarged forenostril on the blind side. A sample of soles clearly related to S. senegalensis was caught in the Gulf of Taranto (Ionian Sea), representing the most western finding of this species in the Mediterranean Sea.     

First Microsatellite Loci of Red Mullet (<Emphasis Type="Italic">Mullus barbatus</Emphasis>) and Their Application to Genetic Structure Analysis of Adriatic Shared Stock

In order to study the genetic structure of the Adriatic shared stock of red mullet (Mullus barbatus), we developed a set of dinucleotide microsatellite markers. A dinucleotide-enriched genomic library was obtained, and 6 polymorphic dinucleotide loci were successfully optimized. The markers showed high expected heterozygosity (from 0.68 to 0.92) and allele number (from 12 to 33); thus they appear to be suitable for detecting genetic differences in the population of red mullet. Four Adriatic samples were subsequently analyzed for microsatellite variation, and the results showed subtle but statistically significant genetic differentiation, indicating that the Adriatic red mullet may group into local, genetically isolated populations. No correlation between geographic distance and genetic differentiation was observed. In addition, the evidence of recent bottlenecks in the Adriatic samples indicates that the observed population subdivision might reflect random local allelic variations, generated by reproductive success, survival rates, or fishing pressure.     

Multimodal pressure-flow method to assess dynamics of cerebral autoregulation in stroke and hypertension

Background

This study evaluated the effects of stroke on regulation of cerebral blood flow in response to fluctuations in systemic blood pressure (BP). The autoregulatory dynamics are difficult to assess because of the nonstationarity and nonlinearity of the component signals.

Methods

We studied 15 normotensive, 20 hypertensive and 15 minor stroke subjects (48.0 ± 1.3 years). BP and blood flow velocities (BFV) from middle cerebral arteries (MCA) were measured during the Valsalva maneuver (VM) using transcranial Doppler ultrasound.

Results

A new technique, multimodal pressure-flow analysis (MMPF), was implemented to analyze these short, nonstationary signals. MMPF analysis decomposes complex BP and BFV signals into multiple empirical modes, representing their instantaneous frequency-amplitude modulation. The empirical mode corresponding to the VM BP profile was used to construct the continuous phase diagram and to identify the minimum and maximum values from the residual BP (BP_R) and BFV (BFV_R) signals. The BP-BFV phase shift was calculated as the difference between the phase corresponding to the BP_R and BFV_R minimum (maximum) values. BP-BFV phase shifts were significantly different between groups. In the normotensive group, the BFV_R minimum and maximum preceded the BP_R minimum and maximum, respectively, leading to large positive values of BP-BFV shifts.

Conclusion

In the stroke and hypertensive groups, the resulting BP-BFV phase shift was significantly smaller compared to the normotensive group. A standard autoregulation index did not differentiate the groups. The MMPF method enables evaluation of autoregulatory dynamics based on instantaneous BP-BFV phase analysis. Regulation of BP-BFV dynamics is altered with hypertension and after stroke, rendering blood flow dependent on blood pressure.

     

Characterization of INTA 51-3, a New Atypical Strain of Bacillus thuringiensis from Argentina

Several isolates of Bacillus thuringiensis native to Argentina obtained in a nationwide screening program showed atypical crystal morphology. One of these strains, INTA 51-3, was further characterized in order to determine other features like protein composition of its parasporal crystal, plasmid pattern, identification of cry genes and toxicological properties. B. thuringiensis INTA 51-3 (serovar tohokuensis) had an amorphous inclusion containing a major protein component of ca. 130 kDa. After trypsin digestion of solubilized crystals, SDS-PAGE resolved a unique protease-resistant peptide of ca. 90 kDa. The plasmid pattern from INTA 51-3 resembled that of the standard strain HD-1. However, Southern analysis showed no hybridization to fragments of cry1Aa, cry2Aa, cry3A, and cry11A genes. Degenerate primers were used for identification of the cry1 genes by PCR. Nevertheless, the presence of cry1 type gene(s) in B. thuringiensis INTA 51-3 was confirmed. Highly concentrated crystal suspensions showed to be weakly toxic only to lepidopteran species. Received: 23 May 2000 / Accepted: 26 June 2000     

Efflux pumps expression and its association with porin down-regulation and β-lactamase production among <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> causing bloodstream infections in Brazil

Background  

Multi-drug efflux pumps have been increasingly recognized as a major component of resistance in P. aeruginosa. We have investigated the expression level of efflux systems among clinical isolates of P. aeruginosa, regardless of their antimicrobial susceptibility profile.     

Aspidosperma (Apocynaceae) plant cytotoxicity and activity towards malaria parasites. Part II: experimental studies with Aspidosperma ramiflorum in vivo and in vitro

Several species of Aspidosperma plants are used to treat diseases in the tropics, including Aspidosperma ramiflorum, which acts against leishmaniasis, an activity that is experimentally confirmed. The species, known as guatambu-yellow, yellow peroba, coffee-peroba andmatiambu, grows in the Atlantic Forest of Brazil in the South to the Southeast regions. Through a guided biofractionation of A. ramiflorum extracts, the plant activity against Plasmodium falciparum was evaluated in vitro for toxicity towards human hepatoma G2 cells, normal monkey kidney cells and nonimmortalised human monocytes isolated from peripheral blood. Six of the seven extracts tested were active at low doses (half-maximal drug inhibitory concentration < 3.8 µg/mL); the aqueous extract was inactive. Overall, the plant extracts and the purified compounds displayed low toxicity in vitro. A nonsoluble extract fraction and one purified alkaloid isositsirikine (compound 5) displayed high selectivity indexes (SI) (= 56 and 113, respectively), whereas compounds 2 and 3 were toxic (SI < 10). The structure, activity and low toxicity of isositsirikine in vitro are described here for the first time in A. ramiflorum, but only the neutral and precipitate plant fractions were tested for activity, which caused up to 53% parasitaemia inhibition of Plasmodium berghei in mice with blood-induced malaria. This plant species is likely to be useful in the further development of an antimalarial drug, but its pharmacological evaluation is still required.     

Appetite regulation: The central role of melatonin in Danio rerio

Melatonin is the hormonal mediator of photoperiodic information to the central nervous system in vertebrates and allows the regulation of energy homeostasis through the establishment of a proper balance between energy intake and energy expenditure. The aim of this study was to evaluate the role of melatonin in appetite central control analyzing the involvement of this hormone in the regulation of feeding behavior in the zebrafish Danio rerio. For this purpose, the effect of two different melatonin doses (100 nM and 1 μM) administered for 10 days, via water, to zebrafish adults was evaluated at both physiological and molecular level and the effect of melatonin was considered in relation to the most prominent systems involved in appetite regulation. For the first time, in fact, melatonin control of food intake by the modulation of leptin, MC4R, ghrelin, NPY and CB1 gene expression was evaluated.The results obtained indicate that melatonin significantly reduces food intake and the reduction is in agreement with the changes observed at molecular level. A significant increase in genes codifying for molecules involved in feeding inhibition, such as leptin and MC4R, and a significant reduction in the major orexigenic signals including ghrelin, NPY and CB1 are showed here.Taken together these results support the idea that melatonin falls fully into the complex network of signals that regulate food intake thus playing a key role in central appetite regulation.