Deep-water macroalgae from the Canary Islands: new records and biogeographical relationships

Due to the geographical location and paleobiogeography of the Canary Islands, the seaweed flora contains macroalgae with different distributional patterns. In this contribution, the biogeographical relations of several new records of deep-water macroalgae recently collected around the Canarian archipelago are discussed. These areBryopsidella neglecta (Berthold) Rietema,Discosporangium mesarthrocarpum (Meneghini) Hauck,Hincksia onslowensis (Amsler et Kapraun) P. C. Silva,Syringoderma floridana Henry,Peyssonnelia harveyana J. Agardh,Cryptonemia seminervis (C. Agardh) J. Agardh,Botryocladia wynnei Ballantine,Gloiocladia blomquistii (Searles) R. E. Norris,Halichrysis peltata (W. R. Taylor) P. Huvé et H. Huvé,Leptofauchea brasiliensis Joly, andSarcodiotheca divaricata W. R. Taylor. These new records, especially those in the Florideophyceae, support the strong affinity of the Canary Islands seaweed flora with the warm-temperate Mediterranean-Atlantic region. Some species are recorded for the first time from the east coast of the Atlantic Ocean, enhancing the biogeographic relations of the Canarian marine flora with that of the western Atlantic regions.     

Selection of synthetic proteins to modulate the human frataxin function

Frataxin is a kinetic activator of the mitochondrial supercomplex for iron-sulfur cluster assembly. Low frataxin expression or a decrease in its functionality results in Friedreich's Ataxia (FRDA). With the aim of creating new molecular tools to study this metabolic pathway, and ultimately, to explore new therapeutic strategies, we have investigated the possibility of obtaining small proteins exhibiting a high affinity for frataxin. In this study, we applied the ribosome display approach, using human frataxin as the target. We focused on Affi_224, one of the proteins that we were able to select after five rounds of selection. We have studied the interaction between both proteins and discussed some applications of this specific molecular tutor, concerning the modulation of the supercomplex activity. Affi_224 and frataxin showed a K_D value in the nanomolar range, as judged by surface plasmon resonance analysis. Most likely, it binds to the frataxin acidic ridge, as suggested by the analysis of chemical shift perturbations (nuclear magnetic resonance) and computational simulations. Affi_224 was able to increase Cys NFS1 desulfurase activation exerted by the FRDA frataxin variant G130V. Importantly, Affi_224 interacts with frataxin in a human cellular model. Our results suggest quaternary addition may be a new tool to modulate frataxin function in vivo. Nevertheless, more functional experiments under physiological conditions should be carried out to evaluate Affi_224 effectiveness in FRDA cell models.     

Age structure, growth and reproduction of Leuciscus pyrenaicus in an intermittent stream in the Guadalquivir river basin, southern Spain

The age, growth and reproduction of Leuciscus pyrenaicus (Günther, 1868), an endemic cyprinid from the Iberian Peninsula, was studied from November 1987 to September 1989 in a small seasonal tributary of the Guadalquivir river basin. Maximum fork lengths observed were a 160 mm male with six scale annuli and a 171 mm female aged 7 +. Maximum ages observed were 7 + in males and 8 + in females. There were no significant differences in the annual growth increments between sexes. Seasonal growth period started in March and continued for 5 to 6 months. Mean lengths of 1 + specimens onwards diminished during summer and/or autumn. Males and females matured in their third and fourth year of life respectively. The overall sex ratio (272 males: 310 females) differed significantly from equality. Spawning began in May and ended in July. L. pyrenaicus is a multiple spawner that releases a minimum of two batches of eggs per female each year. Eggs in each batch were similar in both size (egg diameter) and number released. The relationship between fecundity (Fee) and fork length (mm) was represented by the formula: Fec=1.96 10⁻³ L^2.50.     

Age structure,growth and reproduction ofRutilus lemmingii in an intermittent stream of the Guadalquivir river basin,southern Spain

The age, growth and reproduction ofRutilus lemmingii (Steindachner, 1866), an endemic cyprinid from the Iberian Peninsula, was studied for over a period of two years in a small seasonal tributary of the Guadalquivir river basin. Approximately 65 % of the total growth in length occured in the first year of life. Males reached a maximum age of 3+ yr (Fork Length, F.L. = 114 mm) and females 4+ yr (F.L. = 144 mm). Both sexes matured during their second year of life (1 +). The overall sex ratio (334 males to 389 females) differed significantly from unity. Somatic condition decreased markedly during the reproductive period of March to May.R. lemmingii is a multiple spawner and releases two batches of eggs per female each year. Mean egg diameter of the first batch was larger than the second one. The regression between fecundity and Fork Length (mm) was: Fec = 0.014 F.L.Z.^2.858 Compared with available information, thisR. lemmingii population, located at a lower latitude, is characterized by fast growth, early maturity, high level of reproductive effort, and a short life-span. These life-history characteristices are typical of species in unstable environments, where adult mortality is high, variable or unpredictable.     

A newZornia species in the Flora of Cuba

A newZornia species from Cuba, the endemicZornia arenicola sp. nova, is described. It was found on moving sand dunes between the town of Guane and the village of Cortes (Pinar del Rio province).     

The nitrogen cycle in a ‘Terra Firme’ rainforest on oxisol in the Amazon territory of Venezuela

Standing stocks and fluxes of nitrogen, including nitrogen fixation and denitrification, were measured in a tropical rainforest on Oxisol in the Amazon Territory of Venezuela. The standing stock of nitrogen was comparable to that of temperate forests, but was higher than that in an adjacent forest on Spodosol. Fluxes were higher than in forests in the temperate zone, but lower than in another tropical forest on more fertile soil. Even though nitrogen was abundant, this does not mean that nitrogen could not be limiting to agriculture if the forest is cleared and the land cultivated. The nitrogen fixing and nitrogen conserving mechanisms are dependent upon the structure of the undisturbed forest, and destruction of the forest would eventually decrease the input of nitrogen to the soil.     

Effect of heparin on the utilization in vitro of labelled glycerides from triglyceride-rich lipoproteins in rat adipose tissue

Triglyceride-rich lipoproteins from adult rat plasma were labelled in vivo with 3H in the esterified fatty acids and 14C in the labelled glyceride glycerol of neutral lipids by injecting i.v. sodium 9-10 (n)-[3H] palmitate and [U-14C] glycerol, after which the prelabelled lipoproteins were purified by ultracentrifugation and dialysis. The lipoproteins were incubated in vitro, in the presence or not of heparin, with pieces of epididymal fat pads or isolated adipocytes from fed rats. The disappearance of both [3H]- and [14C] lipids from the media was greater when incubations were performed with adipocytes than with fat-pad pieces and it increased with heparin in both preparations. More 3H-label than 14C was found in the tissue lipids, a higher percentage being present in adipocytes than in fat-pad pieces, and the amount of label in tissue lipids was always enhanced by heparin. Some 14C-label appeared as esterified fatty acids in both tissue preparations and it also was enhanced by the presence of heparin. These findings are in agreement with the recognized influence of heparin on the release of lipoprotein lipase and show the direct relationship between heparin action and tissue ability to take up products of lipoprotein triglyceride breakdown. They also demonstrate the ability of adipose tissue to metabolize glycerol coming from the hydrolysis of lipoprotein glycerides.     

Fructose 1,6-bisphosphatase: Dissociation of AMP cooperativity and AMP inhibition by carbamylation

Selective treatment of pig kidney fructose 1,6-bisphosphatase with potassium cyanate leads to the formation of an active carbamylated enzyme that has lost the cooperative interactions among AMP sites, but retains sensitivity to inhibition of catalytic activity by the regulator AMP. Incorporation data on [¹⁴C]KNCO indicate that the loss of enzyme cooperativity at the AMP sites is related to selective carbamylation of four lysine residues per mole of tetrameric enzyme. Exhaustive carbamylation suggests that a second lysine residue per subunit is essential for AMP inhibition.     

Elevated levels of polyneuronal innervation persist for as long as two years in reinnervated frog neuromuscular junctions

When the nerve to an adult frog sartorius muscle is crushed, and axons are allowed to regenerate, the level of polyneuronal innervation at reinnervated neuromuscular junctions is higher than normal. With time, much of this polyneuronal innervation is reduced by the process of synapse elimination (Werle and Herrera, 1988). Using intracellular recording, we estimated the level of polyneuronal innervation in adult frog (Rana pipiens) sartorius muscles 2 years (range: 1.7-2.4 years) after crushing the sartorius nerve. We found that 27% (S.E. = 1.4%) of the junctions in muscles 2 years after reinnervation were polyneuronally innervated, whereas only 10% (S.E. = 1.2%) of the junctions in normal frog muscles were polyneuronally innervated. Thus, the synapse elimination that occurs following reinnervation does not restore the normal level of polyneuronal innervation. Histological comparisons of junctional structure between muscles 2 years after reinnervation and normal muscles revealed substantial differences. Reinnervated junctions had a greater length of synaptic gutter apposed by nerve terminal processes, more axonal inputs, more empty synaptic gutter, more instances of single synaptic gutters innervated by more than one axon, and longer lengths of nerve terminal processes that connect synaptic gutters within a junction. On the basis of this physiological and anatomical evidence, we conclude that nerve injury causes persistent changes in the pattern of muscle innervation.     

Effects of progesterone and estradiol on the proliferation of phytohemagglutinin-stimulated human lymphocytes

In this paper we report on a study to elucidate whether the response of human lymphocytes to mitogenic stimulation was modified by physiological changes which occur during the menstrual cycle. Experiments with untreated cultures showed intra-individual variation to mitogen stimulation in female lymphocyte cultures, but a significant correlation between the menstrual cycle and the proliferation kinetics of lymphocytes was not found. Consequently, we performed experiments in which two of the hormones that regulate the menstrual cycle in women, estradiol and progesterone, were added to cultured human lymphocytes obtained from both men and women. The results indicate that both hormones at physiological concentrations have the capacity to modify the proliferation of PHA-stimulated human lymphocytes. Therefore, both hormones could play a role in the induction of the intra-individual variation observed in the untreated female cultures. However, in vivo other factors could also modify the proliferation kinetics of human lymphocytes preventing the demonstration of the effects of a single factor, such as the hormonal changes occurring during the menstrual cycle.