Detection and Molecular Characterization of Phytoplasma associated with Lethal Yellowing Disease of Coconut Palms in Cuba

Lethal Yellowing (LY) disease of coconut palm (Cocos nucifera L.) in Cuba has been reported since the end of the 19th century. In order to ascertain the presence of phytoplasmas associated with this disease, leaf samples were taken from plants showing typical disease symptoms and assayed for the LY agent by the polymerase chain reaction (PCR) using LY‐specific primers. Selected PCR amplification products were cloned, sequenced and compared to that of a Mexican LY isolate from the Yucatán region. The results obtained confirm the presence of LY phytoplasma in Cuba. Cuban and Mexican isolates show an overall high degree of sequence similarity with occasional point mutations and small deletions or insertions. Based on these identified genetic differences, LY isolates from the Havana and the Yucatán region cluster together and apart from isolates originating at Maisí in eastern Cuba.     

Distinct sequence elements control the specificity of G protein activation by muscarinic acetylcholine receptor subtypes.

Relatively little is understood concerning the mechanisms by which subtypes of receptors, G proteins and effector enzymes interact to transduce specific signals. Through expression of normal, hybrid and deletion mutant receptors in Xenopus oocytes, we determined the G protein coupling characteristics of the functionally distinct m2 and m3 muscarinic acetylcholine receptor (mAChR) subtypes and identified the critical receptor sequences responsible for G protein specificity. Activation of a pertussis toxin insensitive G protein pathway, leading to a rapid and transient release of intracellular Ca2+ characteristic of the m3 receptor, could be specified by the transfer of as few as nine amino acids from the m3 to the m2 receptor. In a reciprocal manner, transfer of no more than 21 residues from the m2 to the m3 receptor was sufficient to specify activation of a pertussis toxin sensitive G protein coupled to a slow and oscillatory Ca2+ release pathway typical of the m2 subtype. Notably, these critical residues occur within the same region of the third cytoplasmic domain of functionally distinct mAChR subtypes.     

DNA barcoding of deep‐water notacanthiform fishes (Teleostei,Elopomorpha)

Notacanthiformes Goodrich, 1909, is an order of deep‐sea teleost fishes with a leptocephalus larval stage whose biology and systematics are not widely known. The aim of this work was to apply the DNA barcode standard, based on COI sequence variation, to the delimitation of the species of this order, which is composed by the families Halosauridae (halosaurus) and Notacanthidae (spiny eels). The sequence data used for the analyses were obtained from two sources: 71 samples collected during oceanographic surveys in the North Atlantic Ocean (including the rare species Lipogenys gillii Goode & Bean, 1895) and 95 sequences collected from the BOLD data set. The neighbor‐joining analysis of the barcodes was successful in identifying 96% of the specimens, representing 9 of 16 and 9 of 10 of the recognised species of halosaurus and spiny eels, respectively, including all the current genera. The comparison between the Atlantic and the BOLD data sets also flagged the possibility of occurrences of misidentification and cryptic species. A modern molecular tool like the DNA barcoding supports the previously morphological‐based systematics of the order Notacanthiformes and will provide better access to the taxonomic knowledge of these deep‐water fishes.     

Production of rhamnolipids in solid-state cultivation: Characterization,downstream processing and application in the cleaning of contaminated soils

Pseudomonas aeruginosa UFPEDA 614 produced a rhamnolipid biosurfactant when grown on sugarcane bagasse impregnated with a solution containing glycerol. Biosurfactant levels reached 40 g of rhamnolipid per kilogram of dry initial substrate after 12 days. On the basis of the volume of liquid used, the biosurfactant levels were similar to those obtained in submerged liquid culture of a medium identical to the impregnating solution. The properties of the biosurfactant were very similar to those obtained with rhamnolipids produced in submerged culture, with a critical micelle concentration of 46.8 mg/L and an emulsification index at 24 h of over 90% against gasoline. The surface properties were maintained after autoclaving of the fermented solids, meaning that it is possible to minimize safety risks by killing the producing organism with a heat treatment of the solids prior to product extraction. The biosurfactant was used in the washing of soils contaminated with gasoline. An aqueous biosurfactant solution was 3.2-fold more efficient than water in leaching organic material from the soil, demonstrating the viability of application of rhamnolipids in the bioremediation of soils contaminated with gasoline.     

Evaluation of diuron tolerance and biotransformation by the white-rot fungus Ganoderma lucidum

The white rot basidiomycete Ganoderma lucidum was evaluated for its capability to tolerate and to degrade the herbicide diuron. Diuron at a subtoxic concentration was added at the start of the cultivation in glucose liquid stationary cultures. Under this condition diuron was a laccase inducer. Almost 50% of the initially present diuron was removed after 15 d of cultivation. Two diuron metabolites were found N′-(3,4-dichlorophenyl)-N-methylurea (DCPMU) and 3,4-dichlorophenylurea (DCPU). The addition of the cytochrome P450 inhibitors 1-aminobenzotriazole and piperonyl butoxide reduced significantly the capability of the fungus in degrading diuron. The activities of superoxide dismutase and catalase were significantly increased in the mycelial extracts by the presence of diuron. On the other hand, diuron did not cause any significant alteration in the levels of reactive oxygen species. Additionally, laccase could also degrade diuron in vitro and this degradation was increased by the addition of synthetic mediators, 3-ethylbenzthiazoline-6-sulphonic acid and acetylacetone. Significant reduction in the toxicity, as evaluated by the Lactuca sativa bioassay, was observed after G. lucidum treatment. In conclusion, G. lucidum is able to metabolize diuron by intra- and extracellular mechanisms, without the accumulation of toxic products.     

Comparison of three estrus detection systems during summer in a large commercial dairy herd

The objective of the study was to compare three systems for estrus detection and combinations of these systems on a large commercial dairy (1075 lactating cows) during stress of summer heat. At 37-45 days in milk (DIM), 255 cows were fitted with a HeatWatch device (HW; DDx Inc., Denver, CO), an activity sensor ALPRO (ALPRO; DeLaval Inc., Kansas City, MO), and visually observed (VO) three times daily. Pregnancy status was determined by uterine palpation per rectum 35-49 days following artificial insemination (AI). Effects of DIM, parity, standing events, inseminator, and interval between onset of estrus and AI on conception rates were determined using logistic regression. Efficiencies for detection of estrus, determined by comparing detected periods of estrus with a theoretical total of 570 periods, were 49.3% (VO), 37.2% (ALPRO), 48.0% (HW), and 80.2% for all three systems simultaneously. Conception rates (LSM+/-S.E.) for cows detected by one or more of the three systems were 6.2+/-3.9 for VO, 19.8+/-5.6 for ALPRO, 17.3+/-5.0 for HW, 22.8+/-7.0 for VO+ALPRO, 26.9+/-4.6 for VO+HW, 23.2+/-5.2 for ALPRO+HW, and 18.4+/-4.7 for VO+ALPRO+HW. Inseminations performed during no and mild heat stress (temperature-humidity index; THI< or =76) had greater conception rate (P<0.05; 38.8%) compared to AI performed during moderated heat stress conditions (THI>76; 17.6%). Number of mounts were higher for primiparous versus multiparous cows (P<0.05). Cows over 80 DIM during estrus exhibited fewer (P<0.05) standing events. The highest conception rate occurred with the combination of VO+HW, which confirms the premise that combination of multiple systems enhances both the efficiency and accuracy of estrus detection.     

Phytoplankton dynamics in a deep, tropical, hyposaline lake

The annual variation of the phytoplankton assemblage of deep (64.6 m), hyposaline (8.5 g l^–1) Lake Alchichica, central Mexico (19 ° N, 97° W), was analyzed in relation to thermal regime, and nutrients concentrations. Lake Alchichica is warm monomictic with a 3-month circulation period during the dry, cold season. During the stratified period in the warm, wet season, the hypolimnion became anoxic. N–NH₃ ranged between non detectable (n.d.) and 0.98 mg l^–1, N–NO₂ between n.d. and 0.007 mg l^–1, N–NO₃ from 0.1 to 1.0 mg l^–1 and P–PO₄ from n.d. to 0.54 mg l^–1. Highest nutrient concentrations were found in the circulation period. Chlorophyll a varied from <1 to 19.8 g l^–1 but most values were <5 g l^–1. The euphotic zone (>1% PAR) usually comprised the top 15–20 m. Nineteen algae species were identified, most of them are typical inhabitants of salt lakes. Diatoms showed the highest species number (10) but the small chlorophyte Monoraphidium minutum, the single-cell cyanobacteria, Synechocystis aquatilis, and the colonial chlorophyte, Oocystis parva, were the numerical dominant species over the annual cycle. Chlorophytes, small cyanobacteria and diatoms dominated in the circulation period producing a bloom comparable to the spring bloom in temperate lakes. At the end of the circulation and at the beginning of stratification periods, the presence of a bloom of the nitrogen-fixing cyanobacteria, N. spumigena, indicated nitrogen-deficit conditions. The well-stratified season was characterized by low epilimnetic nutrients levels and the dominance of small single-cell cyanobacteria and colonial chlorophytes. Phytoplankton dynamics in tropical Lake Alchichica is similar to the pattern observed in some deep, hyposaline, North American temperate lakes.     

Partial trisomy 14q

Summary A dysmorphic female born with partial trisomy of the proximal segment of the long arm of chromosome 14 had 47 chromosomes. The extra one was acrocentric, smaller than the D group, and bigger than the G-chromosome group. By GTG banding it was identified as a deleted chromosome 14, the karyotype being 47,XX,+del 14(q24). Chromosome analysis of the parents was normal.     

Diversity patterns and food web structure in a Mediterranean intermittent stream

In this work we present the results of a one‐year study on the macroinvertebrate community in an intermittent stream in southern Spain. We have studied the taxonomic composition, diversity and food web monthly in order to consider temporal variability in these parameters. More than 60 macroinvertebrate taxa have been recorded in the stream, but they do not cohabit at the same time. Many of them join the community at the beginning of the wet period. Afterwards, some new taxa incorporate but some others disappear. This leads to huge fluctuations in the diversity of the community and in the food web of different sampling dates. These variations are linked to environmental disturbances, mainly to flow peaks and minimums. From a relatively well structured, but simple, food web at the beginning of the wet period, it can be seen how several trophic levels disappear with time, and how several organisms change or extend their trophic function within it. We relate these variations to the intermediate disturbance hypothesis and discuss the resilience of the community of this intermittent stream (© 2012 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Receptor protein tyrosine phosphatase alpha participates in the m1 muscarinic acetylcholine receptor-dependent regulation of Kv1.2 channel activity.

The phosphorylation state of a given tyrosine residue is determined by both protein tyrosine kinase (PTK) and protein tyrosine phosphatase (PTP) activities. However, little is known about the functional interaction of these opposing activities at the level of an identified effector molecule. G protein-coupled receptors (GPCRs), including the m1 muscarinic acetylcholine receptor (mAChR), regulate a tyrosine kinase activity that phosphorylates and suppresses current generated by the Kv1.2 potassium channel. We examined the possibility that PTPs also participate in this signaling pathway since the tyrosine phosphatase inhibitor vanadate increases the extent of both Kv1.2 phosphorylation and suppression. We show that an endogenous transmembrane tyrosine phosphatase, receptor tyrosine phosphatase alpha (RPTPalpha), becomes tyrosine phosphorylated and co-immunoprecipitates with Kv1.2 in a manner dependent on m1 receptor activation. The N- and C-termini of Kv1.2 are shown to bind RPTPalpha in vitro. Overexpression of RPTPalpha in Xenopus oocytes increases resting Kv1.2 current. Biochemical and electrophysiological analysis reveals that recruiting RPTPalpha to Kv1.2 functionally reverses the tyrosine kinase-induced phosphorylation and suppression of Kv1.2 current in mammalian cells. Taken together, these results identify RPTPalpha as a new target of m1 mAChR signaling and reveal a novel regulatory mechanism whereby GPCR-mediated suppression of a potassium channel depends on the coordinate and parallel regulation of PTK and PTP activities.