Molecular Cytogenetic Analysis of the European Hake Merluccius merluccius (Merlucciidae,Gadiformes): U1 and U2 snRNA Gene Clusters Map to the Same Location

The European hake (Merluccius merluccius) is a highly valuable and intensely fished species in which a long-term alive stock has been established in captivity for aquaculture purposes. Due to their huge economic importance, genetic studies on hakes were mostly focused on phylogenetic and phylogeographic aspects; however chromosome numbers are still not described for any of the fifteen species in the genus Merluccius. In this work we report a chromosome number of 2n = 42 and a karyotype composed of three meta/submetacentric and 18 subtelo/telocentric chromosome pairs. Telomeric sequences appear exclusively at both ends of every single chromosome. Concerning rRNA genes, this species show a single 45S rDNA cluster at an intercalary location on the long arm of subtelocentric chromosome pair 12; the single 5S rDNA cluster is also intercalary to the long arm of chromosome pair 4. While U2 snRNA gene clusters map to a single subcentromeric position on chromosome pair 13, U1 snRNA gene clusters seem to appear on almost all chromosome pairs, but showing bigger clusters on pairs 5, 13, 16, 17 and 19. The brightest signals on pair 13 are coincident with the single U2 snRNA gene cluster signals. Therefore, the use of these probes allows the unequivocal identification of at least 7 of the chromosome pairs that compose the karyotype of Merluccius merluccius thus opening the way to integrate molecular genetics and cytological data on the study of the genome of this important species.     

Unsaturated fatty acids induce non-canonical autophagy

To obtain mechanistic insights into the cross talk between lipolysis and autophagy, two key metabolic responses to starvation, we screened the autophagy-inducing potential of a panel of fatty acids in human cancer cells. Both saturated and unsaturated fatty acids such as palmitate and oleate, respectively, triggered autophagy, but the underlying molecular mechanisms differed. Oleate, but not palmitate, stimulated an autophagic response that required an intact Golgi apparatus. Conversely, autophagy triggered by palmitate, but not oleate, required AMPK, PKR and JNK1 and involved the activation of the BECN1/PIK3C3 lipid kinase complex. Accordingly, the downregulation of BECN1 and PIK3C3 abolished palmitate-induced, but not oleate-induced, autophagy in human cancer cells. Moreover, Becn1^+/− mice as well as yeast cells and nematodes lacking the ortholog of human BECN1 mounted an autophagic response to oleate, but not palmitate. Thus, unsaturated fatty acids induce a non-canonical, phylogenetically conserved, autophagic response that in mammalian cells relies on the Golgi apparatus.     

Effect of Soil Slope on the Appearance of Mycobacterium avium subsp. paratuberculosis in Water Running off Grassland Soil after Application of Contaminated Slurry

The study assessed the effect of soil slope on Mycobacterium avium subsp. paratuberculosis transport into rainwater runoff from agricultural soil after application of M. avium subsp. paratuberculosis-contaminated slurry. Under field conditions, 24 plots of undisturbed loamy soil 1 by 2 m² were placed on platforms. Twelve plots were used for water runoff: 6 plots at a 3% slope and 6 plots at a 15% slope. Half of the plots of each slope were treated with M. avium subsp. paratuberculosis-contaminated slurry, and half were not treated. Using the same experimental design, 12 plots were established for soil sampling on a monthly basis using the same spiked slurry application and soil slopes. Runoff following natural rainfall was collected and analyzed for M. avium subsp. paratuberculosis, coliforms, and turbidity. M. avium subsp. paratuberculosis was detected in runoff from all plots treated with contaminated slurry and one control plot. A higher slope (15%) increased the likelihood of M. avium subsp. paratuberculosis detection but did not affect the likelihood of finding coliforms. Daily rainfall increased the likelihood that runoff would have coliforms and the coliform concentration, but it decreased the M. avium subsp. paratuberculosis concentration in the runoff. When there was no runoff, rain was associated with increased M. avium subsp. paratuberculosis concentrations. Coliform counts in runoff were related to runoff turbidity. M. avium subsp. paratuberculosis presence/absence, however, was related to turbidity. Study duration decreased bacterial detection and concentration. These findings demonstrate the high likelihood that M. avium subsp. paratuberculosis in slurry spread on pastures will contaminate water runoff, particularly during seasons with high rainfall. M. avium subsp. paratuberculosis contamination of water has potential consequences for both animal and human health.     

<Emphasis Type="Italic">Kerianthera longiflora</Emphasis> (Rubiaceae), a remarkable new species from eastern Brazil,with some observations on <Emphasis Type="Italic">K. preclara</Emphasis>

A new species of Kerianthera, K. longiflora Zappi & C. T. Oliveira (Rubiaceae), has been discovered in relicts of Atlantic Forest in Minas Gerais and Espírito Santo, Brazil. This genus was, until now, thought to be monotypic and to occur only in the Amazon. The morphology, phenology and habitat of the new species are discussed and the IUCN conservation status of this and K. preclara are provided.     

Variegation mutants and mechanisms of chloroplast biogenesis

Variegated plants typically have green‐ and white‐sectored leaves. Cells in the green sectors contain normal‐appearing chloroplasts, whereas cells in the white sectors lack pigments and appear to be blocked at various stages of chloroplast biogenesis. Variegations can be caused by mutations in nuclear, chloroplast or mitochondrial genes. In some plants, the green and white sectors have different genotypes, but in others they have the same (mutant) genotype. One advantage of variegations is that they provide a means of studying genes for proteins that are important for chloroplast development, but for which mutant analysis is difficult, either because mutations in a gene of interest are lethal or because they do not show a readily distinguishable phenotype. This paper focuses on Arabidopsis variegations, for which the most information is available at the molecular level. Perhaps the most interesting of these are variegations caused by defective nuclear gene products in which the cells of the mutant have a uniform genotype. Two questions are of paramount interest: (1) What is the gene product and how does it function in chloroplast biogenesis? (2) What is the mechanism of variegation and why do green sectors arise in plants with a uniform (mutant) genotype? Two paradigms of variegation mechanism are described: immutans (im) and variegated2 (var2). Both mechanisms emphasize compensating activities and the notion of plastid autonomy, but redundant gene products are proposed to play a role in var2, but not in im. It is hypothesized that threshold levels of certain activities are necessary for normal chloroplast development.     

Reactive oxygen species contribute to sleep apnea-induced hypertension in rats

In clinical studies, sleep apnea is associated with hypertension, oxidative stress, and increased circulating endothelin-1 (ET-1). We previously developed a model of sleep apnea by exposing rats to eucapnic intermittent hypoxia (IH-C) during sleep, which increases both blood pressure and plasma levels of ET-1. Because similar protocols in mice increase tissue and plasma markers of oxidative stress, we hypothesized that IH-C generation of reactive oxygen species (ROS) contributes to the development of ET-1-dependent hypertension in IH-C rats. To test this, male Sprague-Dawley rats were instrumented with indwelling blood pressure telemeters and drank either plain water or water containing the superoxide dismutase mimetic, Tempol (4-hydroxy-2,2,6,6-tetramethyl-piperidine-1-oxyl, 1 mM). Mean arterial pressure (MAP) and heart rate (HR) were recorded for 3 control days and 14 treatment days with rats exposed 7 h/day to IH-C or air/air cycling (Sham). On day 14, MAP in IH-C rats treated with Tempol (107 +/- 2.29 mmHg) was significantly lower than in untreated IH-C rats (118 +/- 9 mmHg, P < 0.05). Tempol did not affect blood pressure in sham-operated rats (Tempol = 101 +/- 3, water = 101 +/- 2 mmHg). Immunoreactive ET-1 was greater in plasma from IH-C rats compared with plasma from sham-operated rats but was not different from Sham in Tempol-treated IH-C rats. Small mesenteric arteries from IH-C rats but not Tempol-treated IH-C rats had increased superoxide levels as measured by ferric cytochrome c reduction, lucigenin signaling, and dihydroethidium fluorescence. The data show that IH-C increases ET-1 production and vascular ROS levels and that scavenging superoxide prevents both. Thus oxidative stress appears to contribute to increases in ET-1 production and elevated arterial pressure in this rat model of sleep apnea-induced hypertension.     

Contrasting performances of generalist and specialist Myzus persicae (Hemiptera: Aphididae) reveal differential prevalence of maternal effects after host transfer

Transgenerational maternal effects on performance (rm) after host transfer were evaluated in the generalist aphid Myzus persicae s.s., and in its subspecies specialized on tobacco, M. persicae nicotianae Blackman. We tested whether the performance of these taxa, when reared separately on optimal and suboptimal hosts (as sources of different maternal background) and then transferred to optimal hosts, experienced variations along four successive generations. Additionally, to compare the tolerance of both taxa to stress following host transfers, developmental instability (fluctuating asymmetry and body abnormalities) along the four generations was assessed. Taxon, rearing host, and generation affected the performance after host transfer. In the generalist, there was a significant improvement of rm along generations when transferred from suboptimal to optimal host and a significant decrease when transferred from optimal to optimal host; in the specialist, no increase or decrease occurred in any host transfer treatment. Transfer from suboptimal to optimal hosts caused higher losses of remaining replicates along generations than transfers from optimal to optimal hosts, and the specialist showed higher losses than the generalist. The only significant effect detected in comparisons involving fluctuating asymmetry values was that of taxon on length of siphunculi. Frequency of body abnormalities was not affected by treatments. Collectively, these results show a transgenerational weakening of maternal effects in the generalist but not in the specialist aphid, and suggest that rearing the latter in a suboptimal host causes not easily reversible changes that further give rise to constraints in performance.     

<Emphasis Type="Italic">In vitro</Emphasis>–<Emphasis Type="Italic">ex vitro</Emphasis> salt (NaCl) tolerance of cassava (<Emphasis Type="Italic">Manihot esculenta</Emphasis> Crantz) plants

Three cassava clones (SOM-1, “05”, and “50”) were cultured in vitro on MS medium plus sucrose (30 g L⁻¹) and myo-inositol (100 mg L⁻¹) without plant growth regulators and with additions of 0 (control), 0.5, 1, 1.5, 2, 2.5, and 3 g L⁻¹ NaCl to test their salt tolerance. The same cassava clones were cultivated in greenhouse conditions on a sandy soil substratum and irrigated with 20% strength Hoagland solution, and additions of 0, 4, and 8 g L⁻¹ of NaCl. Salinity negatively affected the survival, development, leaf water content, and mineral composition (mainly by accumulation of Cl and Na) of both in vitro and ex vitro plants, but with different intensity in each clone. In both conditions of culture (in vitro and ex vitro) clone SOM-1, from a desert arid saline zone of Somalia, was the most tolerant and clone “05”, from a rainy region of Ivory Coast, the most sensitive. Clone “50” tolerance to in vitro salt treatments, although lower, was not significantly different from that of SOM-1 but the ex vitro response was similar to “05”. In general, there was a correlation between in vitro and ex vitro behavior of the cassava plant regarding salt tolerance, which would allow the in vitro culture method to be used for selection of salt-tolerant plants of this crop.