Phyllachora species infecting maize and other grass species in the Americas represents a complex of closely related species

The genus Phyllachora contains numerous obligate fungal parasites that produce raised, melanized structures called stromata on their plant hosts referred to as tar spot. Members of this genus are known to infect many grass species but generally do not cause significant damage or defoliation, with the exception of P. maydis which has emerged as an important pathogen of maize throughout the Americas, but the origin of this pathogen remains unknown. To date, species designations for Phyllachora have been based on host associations and morphology, and most species are assumed to be host specific. We assessed the sequence diversity of 186 single stroma isolates collected from 16 hosts representing 15 countries. Samples included both herbarium and contemporary strains that covered a temporal range from 1905 to 2019. These 186 isolates were grouped into five distinct species with strong bootstrap support. We found three closely related, but genetically distinct groups of Phyllachora are capable of infecting maize in the United States, we refer to these as the P. maydis species complex. Based on herbarium specimens, we hypothesize that these three groups in the P. maydis species complex originated from Central America, Mexico, and the Caribbean. Although two of these groups were only found on maize, the third and largest group contained contemporary strains found on maize and other grass hosts, as well as herbarium specimens from maize and other grasses that include 10 species of Phyllachora. The herbarium specimens were previously identified based on morphology and host association. This work represents the first attempt at molecular characterization of Phyllachora species infecting grass hosts and indicates some Phyllachora species can infect a broad range of host species and there may be significant synonymy in the Phyllachora genus.     

Effect of melatonin on hemolymph glucose and lactate levels in the fiddler crab Uca pugilator

Melatonin was injected into intact and eyestalk-ablated fiddler crabs (Uca pugilator), and its effects on hemolymph glucose and lactate levels were studied. In intact crabs, glucose and lactate levels cycled simultaneously, with peaks occurring during early and late photophase. Melatonin caused a shift in the glucose and lactate cycles, with only one peak occurring closer to mid-photophase. In eyestalk-ablated animals, the glucose rhythmicity was lost; lactate cycled, but levels were significantly lower than in intact animals. Melatonin caused a delayed hyperglycemia in eyestalk-ablated animals, with concurrent but much lower increases in lactate. Overall, melatonin demonstrated delayed hyperglycemic effects that do not appear to be mediated solely via eyestalk factors such as crustacean hyperglycemic hormone (CHH), though involvement of the eyestalks cannot be ruled out. An influence on extra-eyestalk CHH secretion is a potential mechanism of melatonin activity.     

Immune humoral response in pigs infected with eggs and posoncospheres of Taenia solium

Due to the importance of cysticercosis in Mexico and Latin America and to the fact that in the last years another mechanism of infection for this disease has been proposed, i.e. through postoncospheres and immunosuppression of the host, we have considered relevant to perform the present work, which consisted in assessing the immune response induced by dexamethasone as well as that produced by parasites in pigs infected with T. solium eggs, or postoncosphere-infected, and in postoncosphere-infected and dexamethasone-treated animals. We used 10 recently weaned pigs, three were used as controls, two of them without the drug and one with it; two were infected with T. solium eggs; five with postoncospheres receiving also dexamethasone three of them. We evaluated the humoral response against parasite antigen using indirect haemagglutination (IH) and ELISA methods. Results of the immune humoral response revealed titres of up to 1:128 in T. solium eggs infected animals, of 1:16 in postoncosphere infected animals, and of 1:32 towards the end of the experiment in postoncosphere plus dexamethasone animals. Absorbance titres with ELISA confirmed these findings. Data obtained by IH show that the antibody titres of the pigs challenged with postoncospheres and postoncospheres plus dexamethasone are positive as compared to the titres obtained in the pigs infected with T. solium eggs. Results from the ELISA confirmed this finding, since, from weeks 14 to 17, the pigs became positive, behaving as those pigs that developed cysticercosis. This is relevant as it indicates that the antiposcosphere antibodies recognized antigens of T. solium larvae.     

p53 Expression in circulating lymphocytes of non-melanoma skin cancer patients from an arsenic contaminated region in Mexico. A pilot study

Arsenic is a common environmental toxicant and epidemiological studies associate arsenic exposure with various pathologic disorders and several types of cancer. Skin cancers are the most common arsenic-induced neoplasias and the prevalence of skin lesions has been reported to be significantly elevated in individuals exposed to arsenic via drinking water in Mexico. Being lymphocytes the main cells used for human monitoring, we evaluated the expression of p53 protein in the lymphocytes from 44 healthy individuals and 19 samples from individuals living in a chronic arsenicism endemic region. Of the latter group, 12 individuals had non-melanoma skin cancer and 9 of them expressed p53 in the circulating lymphocytes, whereas only one of the 7 non-cancer arsenic exposed individuals expressed it. In the healthy non-arsenic exposed group only one from 44 individuals expressed the protein. These results suggest a clear relationship between non-melanoma skin cancer and p53 expression in circulating lymphocytes. p53 expression in circulating lymphocytes should be evaluated as a potential biomarker of effect or susceptibility.     

Progressive iron accumulation induces a biphasic change in the glutathione content of neuroblastoma cells

Glutathione (GSH) constitutes the single most important antioxidant in neurons, whereas iron causes oxidative stress that leads to cell damage and death. Although GSH and iron produce opposite effects on redox cell status, no mechanistic relationships between iron and GSH metabolism are known. In this work, we evaluated in SH-SY5Y neuroblastoma cells the effects of iron accumulation on intracellular GSH metabolism. After 2 d exposure to increasing concentrations of iron, cells underwent concentration-dependent iron accumulation and a biphasic change in intracellular GSH levels. Increasing iron from 1 to 5 microM resulted in a marked increase in intracellular oxidative stress and increased GSH levels. Increased GSH levels were due to increased synthesis. Further increases in iron concentration led to significant reduction in both reduced (GSH) and total (GSH + (2 x GSSG)) glutathione. Cell exposure to high iron concentrations (20-80 microM) was associated with a marked decrease in the GSH/GSSG molar ratio and the GSH half-cell reduction potential. Moreover, increasing iron from 40 to 80 microM resulted in loss of cell viability. Iron loading did not change GSH reductase activity but induced significant increases in GSH peroxidase and GSH transferase activities. The changes in GSH homeostasis reported here recapitulate several of those observed in Parkinson's disease substantia nigra. These results support a model by which progressive iron accumulation leads to a progressive decrease in GSH content and cell reduction potential, which finally results in impaired cell integrity.     

Therapeutic potential of the 2-alkyl and 2-alkylidene-19-nor-(20S)-modified analogs of 1alpha,25-dihydroxyvitamin D3

Five analogs of 19-nor-1alpha,25-dihydroxyvitamin D(3) are described that show highly selective and potent activities. The 2-methylene-19-nor-(20S)-1alpha25-dihydroxyvitamin D(3) (2MD) and its 2alpha-methyl sister are selectively active on the osteoblast. 2MD is bone anabolic and causes bone formation in vivo and in vitro and is being developed as a therapy for bone loss diseases such as osteoporosis. 2-Methylene-19-nor (20S)-bishomo-1alpha-hydroxypregnacalciferol (2BMP) has no activity on calcium in vivo while totally suppressing circulating parathyroid hormone. Its homologs, i.e. 2-methylene-19-nor-1alpha-hydroxy-homopregnacalciferol (2MP) and 2-methylene-19-nor-1alpha-hydroxypregnacalciferol (2MPC) act similarly but are either less selective (2MP) or not as potent (2MPC). These abbreviated side chain analogs will be developed for diseases where a rise in serum calcium is not desired, as for example, cancer, renal osteodystrophy, psoriasis and autoimmune diseases.     

Anchoring 9,371 maize expressed sequence tagged unigenes to the bacterial artificial chromosome contig map by two-dimensional overgo hybridization

Our goal is to construct a robust physical map for maize (Zea mays) comprehensively integrated with the genetic map. We have used a two-dimensional 24 x 24 overgo pooling strategy to anchor maize expressed sequence tagged (EST) unigenes to 165,888 bacterial artificial chromosomes (BACs) on high-density filters. A set of 70,716 public maize ESTs seeded derivation of 10,723 EST unigene assemblies. From these assemblies, 10,642 overgo sequences of 40 bp were applied as hybridization probes. BAC addresses were obtained for 9,371 overgo probes, representing an 88% success rate. More than 96% of the successful overgo probes identified two or more BACs, while 5% identified more than 50 BACs. The majority of BACs identified (79%) were hybridized with one or two overgos. A small number of BACs hybridized with eight or more overgos, suggesting that these BACs must be gene rich. Approximately 5,670 overgos identified BACs assembled within one contig, indicating that these probes are highly locus specific. A total of 1,795 megabases (Mb; 87%) of the total 2,050 Mb in BAC contigs were associated with one or more overgos, which are serving as sequence-tagged sites for single nucleotide polymorphism development. Overgo density ranged from less than one overgo per megabase to greater than 20 overgos per megabase. The majority of contigs (52%) hit by overgos contained three to nine overgos per megabase. Analysis of approximately 1,022 Mb of genetically anchored BAC contigs indicates that 9,003 of the total 13,900 overgo-contig sites are genetically anchored. Our results indicate overgos are a powerful approach for generating gene-specific hybridization probes that are facilitating the assembly of an integrated genetic and physical map for maize.