Evidence of incipient speciation in the Neotropical mangrove Pelliciera rhizophorae (Tetrameristaceae) as revealed by molecular,morphological, physiological and climatic characteristics

Two variants of the Neotropical mangrove species Pelliciera rhizophorae distributed along both sides of the Isthmus of Panama were detected by different colouration of the floral bracts and the size of the floral and vegetative structures. These findings raised questions concerning a possible speciation event in P. rhizophorae, for which a series of macro‐ and microscopic morphological traits (reproductive and vegetative structures), molecular markers from plastid DNA and climatic profiles were analyzed. Samples of P. rhizophorae were collected in three localities from the Panamanian Caribbean and Pacific coasts. The data obtained from molecular markers and morphological traits showed significant differences between the variants. The climatic profiles showed contrasting characteristics of rainfall and temperature in their habitats: variant A is found in wetter zones and variant B occupies drier zones. Evidence suggesting that a process of incipient speciation has occurred in P. rhizophorae in response to ecogeographical isolation due to climatic factors is presented. The presence of two geographically separate genetic‐morphological groups, adapted to contrasting climatic conditions, will be the basis for suggesting the existence of incipient lineages in Pelliciera. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 499–510.     

Fruits of Heterocoma (Vernonieae‐Lychnophorinae): taxonomic significance and a new pattern of phytomelanin deposition in Asteraceae

Heterocoma is a Brazilian endemic genus resulting from the dismemberment of Sipolisiinae, in which only representatives with fruit containing phytomelanin were included in the genus. As the fruits of Asteraceae are known to be systematically important at various taxonomic levels and Heterocoma fruit has not been described previously, we studied the morphology and anatomy of the cypselas of all species of the genus, comparing them with other fruits in the family containing phytomelanin and evaluating the systematic potential at the specific and tribal levels. The fruits were analysed by scanning electron microscopy (SEM) and light microscopy. The morphological features of the fruit, including the carpopodium, ribs and pappi, varied in the genus and demonstrated potential for species discrimination. The anatomy showed a pattern for the genus with a uniseriate exocarp, the outer mesocarp composed of fibres arranged in several layers, the inner mesocarp composed of several layers of parenchyma, the endocarp, and phytomelanin deposited between the inner and outer mesocarp. This anatomical pattern of phytomelanin deposition differs from that of other Asteraceae with phytomelanin in their fruit. Heterocoma is also the only genus in Vernonieae that has phytomelanin deposition in the cypselas. © 2015 The Linnean Society of London, Botanical Journal of the Linnean Society, 2015, 179 , 255–265.     

The NIN Transcription Factor Coordinates Diverse Nodulation Programs in Different Tissues of the Medicago truncatula Root

Biological nitrogen fixation in legumes occurs in nodules that are initiated in the root cortex following Nod factor recognition at the root surface, and this requires coordination of diverse developmental programs in these different tissues. We show that while early Nod factor signaling associated with calcium oscillations is limited to the root surface, the resultant activation of Nodule Inception (NIN) in the root epidermis is sufficient to promote cytokinin signaling and nodule organogenesis in the inner root cortex. NIN or a product of its action must be associated with the transmission of a signal between the root surface and the cortical cells where nodule organogenesis is initiated. NIN appears to have distinct functions in the root epidermis and the root cortex. In the epidermis, NIN restricts the extent of Early Nodulin 11 (ENOD11) expression and does so through competitive inhibition of ERF Required for Nodulation (ERN1). In contrast, NIN is sufficient to promote the expression of the cytokinin receptor Cytokinin Response 1 (CRE1), which is restricted to the root cortex. Our work in Medicago truncatula highlights the complexity of NIN action and places NIN as a central player in the coordination of the symbiotic developmental programs occurring in differing tissues of the root that combined are necessary for a nitrogen-fixing symbiosis.     

Infestation of arboreal nests of coatis by triatomine species,vectors of Trypanosoma cruzi,in a large Neotropical wetland

The coati (Nasua nasua, Carnivora) is a medium‐sized mammal common in the Pantanal of Brazil. Unlike most mammals, coatis construct arboreal nests used for resting and reproduction. In this region, the coati is an important host of Trypanosoma cruzi, the causative agent of Chagas disease. There are two possible routes through coatis can be infected by T. cruzi: the oral route or the vectorial route. However, the relative importance of each of these routes in the infection of coatis and its role in the sylvatic cycle of the parasite are unknown. Our objectives were to investigate: (i) whether coati nests were infested by triatomine bugs, (ii) what species were frequent in the nests, (iii) whether the triatomines in nests were infected by T. cruzi, and (iv) what were the food resources of these triatomines. Eight of the 24 nests sampled were infested with triatomines, a total of 37 specimens of at least two species (Rhodnius stali and Triatoma sordida). In one nest, R. stali and T. sordida co‐occurred and both fed on multiple resources, including coatis. This is the first report of triatomines occurring in arboreal nests of coatis. The co‐occurrence of two different genera of triatomine vectors and coatis within the limited space of the coati nests provide multiple opportunities for the exchange of the protozoan parasite through both the vectorial and oral transmission routes.     

Endothelial nitric oxide synthase uncoupling as a key mediator of melanocyte malignant transformation associated with sustained stress conditions

Melanoma cell lines and cells corresponding to premalignant melanocytes were established by our group after subjecting a nontumorigenic murine melanocyte lineage, melan-a, to sequential cycles of anchorage blockade. Previous results showed that in melan-a cells the superoxide level increases after such procedure. Superoxide production during melanocyte de-adhesion was inhibited by L-sepiapterin, the precursor of eNOS cofactor BH4, and increased by the inhibitor of BH4 synthesis, DAHP, hence indicating a partial uncoupling state of eNOS. The eNOS uncoupling seems to be maintained in cells derived from melan-a, because they present decreased nitric oxide and increased superoxide levels. The inhibition of superoxide production in Tm5 melanoma cells with L-sepiapterin reinforces their eNOS-uncoupled state. The maintenance of oxidative stress seems to be important in melanoma apoptosis resistance because Mn(III)TBAP, a superoxide scavenger, or L-sepiapterin renders Tm5 cells more sensitive to anoikis and chemotherapy. More importantly, eNOS uncoupling seems to play a pivotal role in melanocyte malignant transformation induced by sustained anchorage impediment, because no malignant transformation was observed when L-NAME-treated melanocytes were subjected to sequential cycles of de-adhesion. Our results show that uncoupled eNOS contributes to superoxide production during melanocyte anchorage impediment, contributing to anoikis resistance and malignant transformation.     

Representational Difference Analysis (RDA) reveals differential expression of conserved as well as novel genes during caste-specific development of the honey bee (Apis mellifera L.) ovary

In highly eusocial insects, such as the honey bee, Apis mellifera, the reproductive bias has become embedded in morphological caste differences. These are most expressively denoted in ovary size, with adult queens having large ovaries consisting of 150-200 ovarioles each, while workers typically have only 1-20 ovarioles per ovary. This morphological differentiation is a result of hormonal signals triggered by the diet change in the third larval instar, which eventually generate caste-specific gene expression patterns. To reveal these we produced differential gene expression libraries by Representational Difference Analysis (RDA) for queen and worker ovaries in a developmental stage when cell death is a prominent feature in the ovarioles of workers, whereas all ovarioles are maintained and extend in length in queens. In the queen library, 48% of the gene set represented homologs of known Drosophila genes, whereas in the worker ovary, the largest set (59%) were ESTs evidencing novel genes, not even computationally predicted in the honey bee genome. Differential expression was confirmed by quantitative RT-PCR for a selected gene set, denoting major differences for two queen and two worker library genes. These included two unpredicted genes located in chromosome 11 (Group11.35 and Group11.31, respectively) possibly representing long non-coding RNAs. Being candidates as modulators of ovary development, their expression and functional analysis should be a focal point for future studies.     

Synthesis, molecular modeling and preliminary biological evaluation of a set of 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole as potential antibacterial, anti-Trypanosoma cruzi and antifungal agents

A series of 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole derivatives was synthesized and their activity screened in vitro against Staphylococcus aureus, Trypanosoma cruzi, and Candida albicans. The bioactivity was expressed as minimum inhibitory concentration (MIC) for S. aureus strains, and as fifty-percent inhibitory concentration (IC(50)) of parasite population growth for T. cruzi. A molecular modeling approach was performed to establish qualitative relationships regarding the biological data and the compounds' physicochemical properties. The 5-(4-OC(4)H(9)Ph, 5l), and 5-(4-CO(2)CH(3)Ph, 5o) derivatives were the most active compounds for S. aureus ATCC 25923 (MIC=1.95-1.25 μg/mL) and T. cruzi (IC(50)=7.91 μM), respectively. Also, a preliminary evaluation against C. albicans involving some compounds was performed and the 5-(4-CH(3)Ph, 5e) derivative was the most active compound (MIC=3.28-2.95 μg/mL). In this preliminary study, all synthesized 3-acetyl-2,5-disubstituted-2,3-dihydro-1,3,4-oxadiazole derivatives were active against all microorganisms tested.     

Identification and expression of soul/p22HBP genes in zebrafish

The SOUL/p22HBP family is an evolutionarily ancient group of heme binding proteins with a main function as cytosolic buffer against tetrapyrrole accumulation. Structural and biochemical evidence suggest specialized roles in blood formation, necrotic cell death and chemotaxis. To date, nothing is known about the precise activity and expression patterns of this class of heme binding proteins during development. The zebrafish genome possesses five soul genes belonging to two subgroups, and no p22HBP orthologous gene. Here, spatial and temporal expression patterns are reported for zebrafish soul1, soul2 and soul4 genes. All three soul genes are maternally transcribed, and their zygotic expression takes place in unique (heart, pharynx, yolk syncytial layer, brain, eyes, lateral line) and overlapping (pronephros, pituitary gland, olfactory and otic vesicle) regions of the zebrafish embryo. Our study constitutes the first detailed analysis of soul gene expression in metazoan development, and provides the basis to understand the genetics of tetrapyrrole metabolism in a wide range of embryonic processes.