Biogeography of Iberian freshwater fishes revisited: the roles of historical versus contemporary constraints

Aim The question of how much of the shared geographical distribution of biota is due to environmental vs. historical constraints remains unanswered. The aim of this paper is to disentangle the contribution of historical vs. contemporary factors to the distribution of freshwater fish species. In addition, it illustrates how quantifying the contribution of each type of factor improves the classification of biogeographical provinces. Location Iberian Peninsula, south‐western Europe (c. 581,000 km²). Methods We used the most comprehensive data on native fish distributions for the Iberian Peninsula, compiled from Portuguese and Spanish sources on a 20‐km grid‐cell resolution. Overall, 58 species were analysed after being categorized into three groups according to their ability to disperse through saltwater: (1) species strictly intolerant of saltwater (primary species); (2) species partially tolerant of saltwater, making limited incursions into saltwaters (secondary species); and (3) saltwater‐tolerant species that migrate back and forth from sea to freshwaters or have invaded freshwaters recently (peripheral species). Distance‐based multivariate analyses were used to test the role of historical (basin formation) vs. contemporary environmental (climate) conditions in explaining current patterns of native fish assemblage composition. Cluster analyses were performed to explore species co‐occurrence patterns and redefine biogeographical provinces based on the distributions of fishes. Results River basin boundaries were better at segregating species composition for all species groups than contemporary climate variables. This historical signal was especially evident for primary and secondary freshwater fishes. Eleven biogeographical provinces were delineated. Basins flowing to the Atlantic Ocean north of the Tagus Basin and those flowing to the Mediterranean Sea north of the Mijares Basin were the most dissimilar group. Primary and secondary freshwater species had higher province fidelity than peripheral species. Main conclusions The results support the hypothesis that historical factors exert greater constraints on native freshwater fish assemblages in the Iberian Peninsula than do current environmental factors. After examining patterns of assemblage variation across space, as evidenced by the biogeographical provinces, we discuss the likely dispersal and speciation events that underlie these patterns.     

Astrocyte Resilience to Oxidative Stress Induced by Insulin-like Growth Factor I (IGF-I) Involves Preserved AKT (Protein Kinase B) Activity

Disruption of insulin-like growth factor I (IGF-I) signaling is a key step in the development of cancer or neurodegeneration. For example, interference of the prosurvival IGF-I/AKT/FOXO3 pathway by redox activation of the stress kinases p38 and JNK is instrumental in neuronal death by oxidative stress. However, in astrocytes, IGF-I retains its protective action against oxidative stress. The molecular mechanisms underlying this cell-specific protection remain obscure but may be relevant to unveil new ways to combat IGF-I/insulin resistance. Here, we describe that, in astrocytes exposed to oxidative stress by hydrogen peroxide (H₂O₂), p38 activation did not inhibit AKT (protein kinase B) activation by IGF-I, which is in contrast to our previous observations in neurons. Rather, stimulation of AKT by IGF-I was significantly higher and more sustained in astrocytes than in neurons either under normal or oxidative conditions. This may be explained by phosphorylation of the phosphatase PTEN at the plasma membrane in response to IGF-I, inducing its cytosolic translocation and preserving in this way AKT activity. Stimulation of AKT by IGF-I, mimicked also by a constitutively active AKT mutant, reduced oxidative stress levels and cell death in H₂O₂-exposed astrocytes, boosting their neuroprotective action in co-cultured neurons. These results indicate that armoring of AKT activation by IGF-I is crucial to preserve its cytoprotective effect in astrocytes and may form part of the brain defense mechanism against oxidative stress injury.     

Synthesis and structure-activity relationship of 2-(aminoalkyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives: a novel series of 5-HT(2A/2C) receptor antagonists. Part 2.

Following the programme started at Janssen Research Foundation searching for 5-HT(2A/2C) antagonists, we now report on the synthesis of a series of substituted 2-(Dimethylaminomethyl)-2,3,3a,8-tetrahydrodibenzo[c,f]isoxazolo[2,3-a]azepine derivatives. The 5-HT(2A), 5-HT(2C) and H(1) receptor affinities as well as the mCPP antagonistic activity of the compounds synthesised is described.     

Hypocotyl growth of Pinus pinaster seedlings. Changes in the molecular weight distribution of hemicellulosic polysaccharides

Lorences, E. P., Suárez, L. and Zarra, I. 1987. Hypocotyl growth of Pinus pinaster seedlings. Changes in the molecular weight distribution of hemicellulosic polysaccharides.
The changes in the molecular weight distribution of water-soluble hemicelluloses and xyloglucan during hypocotyl growth of intact seedlings of Pinus pinaster Aiton were investigated. The mass-average molecular weight of total polysaccharides of the hemicellulose fraction soluble in 4% KOH dramatically increased during hypocotyl growth while xyloglucan slightly decreased. These phenomena were due to an increase in the degree of polymerization of an arabinogalactan and a slight depolymer-ization in the xyloglucan present in this fraction. In the hemicellulose fraction soluble in 24% KOH, xyloglucan increased its degree of polymerization from day 7 to 10 after which it decreased slightly. The xyloglucan of the hemicellulose fraction soluble in 4% KOH may thus be involved in cell wall loosening which makes cell wall expansion possible during hypocotyl growth.     

Calcium/calmodulin regulation of ATPase activity and endogenous phosphorylation of mammalian brain actomyosin

Rabbit brain actomyosin showed several fold stimulation of the MgATPase activity by Ca2+ alone and by Ca2+/calmodulin. The calmodulin-binding drug, fluphenazine, abolished the stimulated activity. In the presence of Ca2+, exogenous calmodulin had a biphasic effect on ATPase activity at low concentrations (less than 0.15 microM) and activated the ATPase activity by 60-70% at about 1 microM. Tropomyosin-troponin complex from skeletal muscle did not stimulate the ATPase activity of brain actomyosin, but conferred Ca2+ sensitivity to a skeletal muscle myosin/brain actomyosin mixture. These results indicate the presence of myosin-linked, calmodulin-dependent, Ca2+-regulatory system for brain actomyosin. Heavy and light chains of brain myosin were found to be rapidly phosphorylated by endogenous Ca2+-dependent protein kinase(s). Ca2+-independent phosphorylation of one of the light chains was also observed.     

Tissue plasminogen activator inhibitor in patients with systemic lupus erythematosus and thrombosis.

OBJECTIVE--To examine the relations among tissue plasminogen activator antigen, plasminogen activator inhibitor, the lupus anticoagulant, and anticardiolipin antibodies in patients with systemic lupus erythematosus. DESIGN--Prospective study of blood samples (a) from selected patients with systemic lupus erythematosus whose disease was and was not complicated by a history of thrombosis or recurrent abortions, or both, and (b) from a series of healthy controls with a similar age and sex distribution. SETTING--University based medical clinic. SUBJECTS--23 Patients with definite systemic lupus erythematosus (American Rheumatism Association criteria), of whom 11 (eight women) aged 26-51 had a history of thrombosis or recurrent abortions, or both, and 12 (10 women) aged 23-53 had no such history. 15 Healthy subjects (10 women) aged 25-58 served as controls. MAIN OUTCOME MEASURES--Tissue plasminogen activator concentrations, plasminogen activator inhibitor activities, detection of the lupus anticoagulant, and values of anticardiolipin antibodies in the two groups of patients and in the patients with a history of thrombosis or abortions compared with controls. Other measurements included concentrations of proteins that are known to change during the acute phase of systemic lupus erythematosus--namely, fibrinogen, C3 and C4, and C reactive protein. RESULTS--Patients with a history of thrombosis or abortions, or both, had significantly higher values of tissue plasminogen activator and plasminogen activator inhibitor than patients with no such history. A significant correlation between tissue plasminogen activator and plasminogen activator inhibitor (r = 0.80) was found only in the patients with a history of complications of their disease. The lupus anticoagulant was detected in six of the 11 patients with a history of thrombosis or abortions when tested by measuring the activated partial thromboplastin time but was found in all 11 patients when tested by measuring the diluted activated partial thromboplastin time. Nine of these 11 patients had raised values of anticardiolipin antibodies. The findings showed no relation to the activity of the disease. CONCLUSIONS--A significant correlation between tissue plasminogen activator concentrations and plasminogen activator inhibitor activities was found only in patients whose systemic lupus erythematosus was complicated by a history of thrombosis or recurrent abortions. The findings show that these patients have raised plasminogen activator inhibitor activities, and the frequent association between these raised activities and the presence of the lupus anticoagulant suggests that the two may be linked.     

Circadian rhythm of the endopeptidase 22.19 (EC 3.4.22.19) in the rat brain.

The endopeptidase 22.19 (EC 3.4.22.19) has been associated with the metabolism of neuropeptides by its ability to convert small enkephalin-containing peptides (8 to 13 amino acids) into enkephalins. In addition, this enzyme cleaves the Arg8-Arg9 bond of neurotensin and the Phe5-Ser6 bond of bradykinin. We analyzed the circadian variation of endopeptidase 22.19 in the whole and individual areas of the rat brain. Endopeptidase 22.19 activity was analyzed by high-performance liquid chromatography (HPLC) using bradykinin as an operative substrate. Enzymatic specific activities were analyzed by rhythmometric methods and indicate a circadian fluctuation of endopeptidase 22.19 specific activity (mU of enzyme/mg of protein) in the whole brain [p less than 0.001, mesor (M) = 7.62, amplitude (A) = 2.89, and acrophase (phi) = 23:08 h], striatum (p less than 0.001, M = 2.92, A = 0.62, phi = 23:03 h), hypothalamus (p less than 0.001, M = 3.15, A = 0.86, phi = 01:12 h), periaqueductal gray matter (p less than 0.005, M = 2.62, A = 0.34, phi = 22:35 h), and cerebellum (p less than 0.014, M = 4.27, A = 0.88, phi = 17:12 h). The circadian rhythmicity in endopeptidase 22.19 specific activity suggests that light may have an effect on the peptidase activity in whole brain and in areas of the central nervous system and may be essential for the mechanisms of circadian fluctuations of neuropeptides in the brain.     

A guinea-pig hereditary cataract contains a splice-site deletion in a crystallin gene

A congenital cataract present in guinea pigs provided a unique opportunity to study a hereditary lens diseases at the molecular level. ζ-crystallin, one of the most abundant guinea pig lens proteins, was found to be altered in the lens of cataractous animals. Several ζ-crystallin cDNA clones were isolated from a cataractous lens library and found to contain a 102-bp deletion towards the 3′ end of the coding region. The deletion does not interfere with the reading frame but results in a protein 34 amino acids shorter. Sequence analysis of a normal genomic ζ-crystallin clone revealed that the missing 102-bp fragment corresponds to an entire exon (exon 7). PCR analysis of the genomic DNA isolated from cataractous animals showed that exon 7, though missing from the mRNA, is intact in the cataractous genome. Further sequence analysis of the α-crystallin gene disclosed a dinucleotide delection of the universal AG at the acceptor splice-site of intron 6 of the mutant gene. The presence of this mutation results in the skipping of exon 7 during the mRNA processing which in turn results in the altered ζ-crystallin protein. This if the first time a genomic mutation in an enzyme/crytallin gene has been directly linked to a congenital cataract.     

Repair of UV-induced pyrimidine dimers in the individual genes Gart, Notch and white from Drosophila melanogaster cell lines.

The excision repair of UV-induced pyrimidine dimers was investigated in three genes: Gart, Notch and white in a permanent Drosophila cell line Kc, derived from wild type Drosophila melanogaster embryonic cells. In this cell line Gart and Notch are actively transcribed, whereas white is not expressed. In all three genes UV-induced pyrimidine dimers were removed with the same rate and to the same extent: 60% removal within 16 hours, up to 80-100% in 24 hours after irradiation with 10 or 15 J/m2 UV. These kinetics are similar to the time course of dimer removal measured in the genome overall. No difference in repair of the inactive white locus compared to the active Gart and Notch genes was found. Similar results were obtained using a different wild type cell line, SL2, although repair appeared to be somewhat slower in this cell line. The results are discussed with respect to the data found for gene specific repair in other eukaryotic systems.