Esteban Martínez

Conserving Tropical Tree Diversity and Forest Structure: The Value of Small Rainforest Patches in Moderately-Managed Landscapes

Rainforests are undergoing severe deforestation and fragmentation worldwide. A huge amount of small forest patches are being created, but their value in conserving biodiversity and forest structure is still controversial. Here, we demonstrate that in a species-rich and moderately-managed Mexican tropical landscape small rainforest patches (<100 ha) can be highly valuable for the conservation of tree diversity and forest structure. These patches showed diverse communities of native plants, including endangered species, and a new record for the country. Although the number of logged trees increased in smaller patches, patch size was a poor indicator of basal area, stem density, number of species, genera and families, and community evenness. Cumulative species-area curves indicated that all patches had a similar contribution to the regional species diversity. This idea also was supported by the fact that patches strongly differed in floristic composition (high β-diversity), independently of patch size. Thus, in agreement with the land-sharing approach, our findings support that small forest patches in moderately-managed landscapes should be included in conservation initiatives to maintain landscape heterogeneity, species diversity, and ecosystem services.

B-Function Expression in the Flower Center Underlies the Homeotic Phenotype of Lacandonia schismatica (Triuridaceae)

This article shows that the peculiar expression pattern of a functionally conserved floral gene (APETALA3-like) in the center of the Lacandonia schismatica flower underlies its unique inside-out arrangement (i.e., central stamens surrounded by carpels). Thus, relatively simple genetic alterations may underlie large morphological shifts fixed in extant natural populations. Spontaneous homeotic transformations have been described in natural populations of both plants and animals, but little is known about the molecular-genetic mechanisms underlying these processes in plants. In the ABC model of floral organ identity in Arabidopsis thaliana, the B- and C-functions are necessary for stamen morphogenesis, and C alone is required for carpel identity. We provide ABC model-based molecular-genetic evidence that explains the unique inside-out homeotic floral organ arrangement of the monocotyledonous mycoheterotroph species Lacandonia schismatica (Triuridaceae) from Mexico. Whereas a quarter million flowering plant species bear central carpels surrounded by stamens, L. schismatica stamens occur in the center of the flower and are surrounded by carpels. The simplest explanation for this is that the B-function is displaced toward the flower center. Our analyses of the spatio-temporal pattern of B- and C-function gene expression are consistent with this hypothesis. The hypothesis is further supported by conservation between the B-function genes of L. schismatica and Arabidopsis, as the former are able to rescue stamens in Arabidopsis transgenic complementation lines, and Ls-AP3 and Ls-PI are able to interact with each other and with the corresponding Arabidopsis B-function proteins in yeast. Thus, relatively simple molecular modifications may underlie important morphological shifts in natural populations of extant plant taxa.

Pollen development and fertilization in Lacandonia schismatica (Lacandoniaceae)

The flower of Lacandonia schismatica is bisexual. Three or sometimes four bilocular or trilocular anthers occupy the center of the flower inside the zone of carpels. The anther wall comprises four layers: epidermis; endothecium whose cells develop helical wall thickenings; one middle layer, which disappears early; a tapetum of the secretory type. The tapetal cells apparently form cytoplasmic bridges among themselves. The microspore tetrads are in an isobilateral arrangement, surrounded by a thick wall. The mature anther wall has only two cell layers: epidermis and endothecium. The pollen grain is three-celled by the time germination occurs. Anther dehiscence has not been observed and probably does not occur. Pollination of Lacandonia schismatica occurs in the unopened flower bud

Inside‐Out Flowers Characteristic of Lacandonia schismatica Evolved at Least before Its Divergence from a Closely Related Taxon, Triuris brevistylis

Lacandonia schismatica, a mycoheterotrophic, hermaphroditic monocotyledon endemic to the Lacandon rain forest of southeast Mexico, is the only flowering plant for which a spatial inversion (heterotopy, complete homeosis) of the reproductive floral whorls (stamens and carpels) is known to occur in natural populations. In order to investigate if this autapomorphic inside‐out arrangement of the reproductive organs is fixed in natural populations, we have undertaken extensive and intensive fieldwork spanning several years to locate new populations in addition to the type locality. In parallel, we have also searched for natural variation in floral organ arrangement in Triuris brevistylis, a closely related dioecious triurid that is found in nearby areas of the Lacandon forest. We have found that a small proportion of L. schismatica inflorescences bear unisexual flowers of both sexes, as well as bisexual flowers with differences in the number of reproductive organs. However, in all bisexual flowers, the stamens were always central and the carpels peripheral to them. More important, we have also found that a few T. brevistylis individuals have bisexual flowers with altered positions of stamens and carpels. Among these, flowers with an inside‐out L. schismatica–like floral organ arrangement were observed. We document our findings with scanning electron micrographs, histological sections, and dissection microscope views. The information presented implies that the developmental‐genetic mechanism putatively responsible for homeotic/heterotopic transformations involving floral reproductive organs in the two triurid species originated at least before these taxa diverged from each other. The Mexican triurids may be an example in which the molecular evolutionary events causally related to a major morphological change in plants can best be understood at the microevolutionary scale.

ABIETANOID ACID FROM LEPECHINIA-CAULESCENS

Abstract The aerial parts of Lepechinia caulescens provided the new diterpene 7β-hydroxy-abietan-8(14)-en-18-oic acid 9α,13α-endoperoxide which decomposes to 7β-hydroxy-8α,9α,13α,14α-diepoxy-abietan-18-oic acid. Several known acids and flavonoids were also isolated from this species.

Di- and triterpenoid acids from Lepechinia caulescens☆

Abstract Above ground parts of Lepechinia caulescens afforded the new diterpene 8α(9α),13α(14α)-diepoxy-abietan-18-oic acid. Additional diterpenoid and triterpenoid acids were also characterized from another population of the same species.

The ultrastructural study of the interphase cell nucleus of Lacandonia schismatica (Lacandoniaceae: Triuridales) reveals a non-typical extranucleolar particle

By light and electron microscope cytochemistry we characterized the interphase nucleus of Lacandonia schismatica, the only known species of the new plant family Lacandoniaceae, whose most peculiar feature is the inverted position of the sexual organs, an aspect never found before among flowering plants. Furthermore, we compare it to Triuris alata, a related species, to Voyria aphylla (a dicotyledon), to Gymnosiphon divaricatus (a monocotyledon) and also to saprophytes. The reticulated chromatin of L schismatica and T alata is similar to that of other monocotyledons. In addition, we describe a unique type of RNP granules in the interchromatin space which are about 32 ± 3 nm SD in diameter and occur as huge clusters. They are intermediate in size and spatial distribution between inter‐ and peri‐chromatin granules. We term them ‘Lacandonia granules’. The granules were also found in T alata. They are 31 ± 2 nm in diameter. No significant differences in size were observed between them (P > 0.05). Synaptonemallike complexes and ring‐shaped structures were seen in interphase nuclei of somatic cells of these species. Coiled and nucleolus‐associated bodies, as well as centromeres were also found in these two organisms. On the contrary, Vaphylla and G divaricatus display a chromocentric nuclear organization. The nuclear similarities between L schismatica and T alata suggest extremely close phylogenetic relationships between them.

4CPS-120 Case report: use of vismodegib in a patient with gorlin goltz syndrome

Background Gorlin Goltz Syndrome (SGG) is caused by the mutation of the Hedgehog (Hh) gene. The clinical consequences are related to the production of basal cell carcinomas (BCC) and the alteration of normal tissue development. Vismodegib is a drug that inhibits the Hh signalling pathway by blocking the activation of the transmembrane-7 Smoot-hened receptor. Purpose Evaluation of the effectiveness and safety of vismodegib in a patient with BCC caused by SGG. Material and methods Follow-up of a patient treated with vismodegib as a cause of multiple CBCs. Previous treatment lines, the size and number of BCCs, the suitability of vismodegib in patients with SGG and the adverse effects presented were reviewed. Results A 62-year-old patient was diagnosed with SGG at 22 years of age. The patient’s multiple CBCs from their youth were controlled by surgical interventions, topical 5-fluorouracil, imiquimod, retinoids and photodynamic therapy. In 2016, before the impossibility of submitting the patient with new excision, treatment with vismodegib 150 mg starting every 24 hours. The effectiveness of the treatment has been crucial due to the fact that the second month had a reduction in BCC >30%. During the 13 months of treatment with vismodegib, the patient presented adverse reactions such as joint pain and generalised tiredness throughout the treatment and a punctual increase in the values of the liver enzymes that conditioned the suspension for 10 days. After 10 months of the starting treatment, as a consequence of the adverse effects and at the request of the patient, a therapeutic rest of 2 months was prescribed, restarting again due to the risk of relapse. Conclusion Although we are faced with a syndrome of low incidence and with few studies in terms of available treatments, we have made possible a significant decrease in BCC. Regarding the duration of treatment, the ERIVANCE fundamental study presented a median treatment duration of 9.6 months, having been overcome in our case. All adverse effects are presented in the technical file, highlighting the fatigue and joint pain that have conditioned the therapeutic rest. Reference and/or Acknowledgements 1. Sekulic A, Migden MR, Lewis K, et al. Pivotal ERIVANCE basalcell carcinoma (BCC) study: 12-month update of efficacy andsafety of vismodegib in advanced BCC. J Am Acad Dermatol2015;72(6):1021–1026. e8. No conflict of interest