Global climate is changing at unprecedented rates, causing detrimental effects on vulnerable organisms and forcing them to cope with unfavorable conditions. Ectotherms often adapt to changing abiotic variables by altering their distribution ranges. Amphibians are known to alter their distribution because of rising temperatures. In Puerto Rico we have observed a range-shift to higher elevations in one species of direct-developing frog. Here we considered two species that occur sympatrically in part of their range at El Yunque tropical montane reserve. One species, Eleutherodactylus portoricensis, is presently limited to high elevations above 700 m.a.s.l., although it was previously found down to 400 m.a.s.l. Contrastingly, its congeneric E. coqui, can be found at all elevations (0-1,300 m.a.s.l.). Our objective was to characterize both species’ thermo-physiological profiles and question if the observed range-shift to higher elevations of E. portoricensis was associated to higher physiological sensitivity. We evaluated critical thermal minima and maxima, and thermal preference for three populations: E. portoricensis (850m), and low (180m) and highland (850m) E. coqui. We also evaluated dehydration stress during jumping performance by reducing 5% of their body mass using dry-air chambers. Lastly, we modeled E. portoricensis current and future distribution range under various scenarios of climate change. Our results show that E. portoricensis has a narrower thermal tolerance range and prefers lower temperatures when given a gradient. Also, E. portoricensis showed lower performance levels than E. coqui when dehydrated. Our results suggest that higher physiological sensitivity may explain elevational range contraction on this species. In addition, distribution models show a decrease in occurrence probability later this century in comparison to current projections. Our models also predict a range contraction towards higher elevations. This range shift would most likely result in the extirpation of most E. portoricensis populations. This research highlights the vulnerability of an endemic tree frog in Puerto Rico as a consequence of anthropogenic climate change and the urge to develop effective conservation efforts....

Corals can exhibit much variability in life-history strategies. A proposed categorization recognizes competitive, stress-tolerant and weedy species. 'Competitive' corals invest more energy towards growth, 'stress-tolerant' towards maintenance and 'weedy' towards reproduction. While competitive corals are declining due to climate change and anthropogenic stressors, stress-tolerant and weedy are thriving. We performed a reciprocal transplant experiment between a degraded and a more pristine reef, and measured the physiological (Symbiodinium density, chlorophyll a concentration, protein concentration) and immunological (oxidative stress) response of the stresstolerant Pseudodiploria strigosa and Orbicella annularis, and the weedy Porites astreoides. Results indicate that the studied species can rapidly and successfully acclimate to local environmental conditions. Comparisons among species suggest that the physiological and immunological response in P. astreoides, P. strigosa and O. annularis are more influenced by species-specificity than by life-history strategy....

In this thesis, we explore the cognitive basis for the emergence of individual foraging strategies (IFS) across multiple honey bee subspecies using Reversal Learning assays and Free-Flying foraging problems. In Chapter 1 ...

Butterfly wing patterns have captivated evolutionary and developmental biologists for decades because of their vast diversity. Studies have focused on the molecular basis of pattern variation in the Nymphalidae, with little effort put toward skippers, family Hesperiidae. This study had two aims: identify the presence of Wnt genes through ISH and pharmacological drug injections, and test differentially expressed genes in three developmental stages, between wing types, and between wing compartments of E. clarus using RNA-sequencing. I hypothesized, that a simple yet modular set of genes was involved in wing pattern development of the skipper, similar to that of nymphalid butterflies and that genes such as WntA and Ubx would be differentially expressed as in nymphalids. ISH confirmed the presence of two Wnt genes and RNA-seq provided evidence of differential expression, suggesting that the genes underlining wing pattern diversity are being shared between these two distantly related families....

Pathogenesis often involves the formation of biofilms and adaptation to low oxygen environments to survive in the human body. Aspergillus fungi are opportunistic pathogens that can form biofilms and adapt to microenvironments that vary in oxygen. However, interactions between biofilms and low oxygen environments are not well understood, The first chapter, we studied biofilm formation in vitro by A. fumigatus, A. niger, A. flavus, and A. terreus in microaerophilic conditions. All species formed biofilms in microaerophilic conditions. In the second chapter, we compared biofilm formation vs. planktonic cells of Aspergillus spp. in microaerophilic vs. aerobic conditions and compared resistance to Amphotericin B in different conditions. A. flavus was more resistant to AMB than A. fumigatus in microaerophilic conditions. In the third chapter, we studied the roles of melanin in biofilm formation and virulence. We evaluate biofilms formation in microaerophilic vs. aerobic conditions in A. fumigatus mutants deficient in pyomelanin (hppd) and DHN-melanin (alb1). Melanin was not crucial for biofilm formation. The alb1 mutants showed increased metabolic activity in a microaerophilic environment. Also, the alb1-mutant was more virulent in Drosophila melanogaster than several wild type strains of A. fumigatus. These data support why aspergillosis infections are challenging to eradicate....

On this thesis, a synthetic human urine formulation alike real urine and that can be ideal for P. vulgaris growth is identified. Additionally, urease activity from robust P. vulgaris is assessed electrochemically by measuring ammonia oxidation currents from synthetic human urine cultures via cyclic voltammetry. The results of this research will be fundamental for future experiments leading to the continuous growth of P. vulgaris and urease activity in real human urine....

Essential Thrombocytemia (ET) is part of the spectrum of myeloproliferative disorders that affect the myeloid progenitor cells. This neoplasm is characterized by a cytokine overproduction, persistent thrombocytosis, ...

Malaria is a devastating disease that kills millions of people each year, and the emergence of multidrug-resistant Plasmodium parasites poses a major challenge to global malaria control efforts. This dissertation evaluated the antiplasmodial activity of seven novel hydrazone compounds (referred to as CB compounds: CB-27, CB-41, CB-50, CB-53, CB-58, CB-59, and CB-61) against multiple stages of Plasmodium parasites. All CB compounds exhibited broad-spectrum antiplasmodial activity, inhibiting the growth of drug-resistant or sensitive strains of Plasmodium falciparum blood stages with high potency. Interestingly, CB-41 showed prophylactic activity against hypnozoites and liver schizonts in the Plasmodium cynomolgi, a primate model for Plasmodium vivax. Four CB compounds (CB-27, CB-41, CB-53, and CB-61) inhibited P. falciparum oocyst formation in mosquitoes, and five CB compounds (CB-27, CB-41, CB-53, CB-58, and CB-61) hindered the in vitro development of Plasmodium berghei ookinetes. The CB compounds did not inhibit the activation of P. berghei female and male gametocytes in vitro. Six CB compounds showed no inhibition of Plasmodium glutathione S-transferase as a putative target, and no cytotoxicity was exhibited in HepG2 cells. The development and application of the Machine Learning Synergy Predictor (MLSyPred©) tool, an open-sourced and accessible tool for predicting synergistic antimalarial drug combinations, is a significant contribution to malaria research. Using predictions made by MLSyPred©, P. berghei blood stage isobologram analyses showed synergy between CB-61 and FDA-approved antimalarial drugs clindamycin and halofantrine, suggesting that CB compounds could be used in combination therapy to enhance the efficacy of existing antimalarial drugs. These findings demonstrate that CB compounds (CB-27, CB-41, CB-53, and CB-61) are promising candidates for further development as broad-spectrum antimalarial drugs that could treat multidrug-resistant malaria and prevent transmission. CB compounds and the MLSyPred© tool have the potential to make important contributions to malaria research....

I explore the distribution and germination patterns of the epiphytic orchid, Psychilis kraenzlinii in the Susua State Forest, Puerto Rico. The orchid grows on a subset of the available tree species and shows preference for the endemic Machaonia portorricensis (Rubiaceae). The orchid preferred trees with smoother bark with high water holding capacity and low water retention capacity. Microclimatic conditions under which embryos began pre-germination stages mirrored that of the adult orchid, but germination did not, suggesting that suitable germination sites are not necessarily the best sites for later stages of development....
Exploré la distribución y los patrones de germinación de la orquídea epífita, Psychilis kraenzlinii en el Bosque Estatal de Susúa. Psychilis kraenzlinii crece en un subconjunto de las especies de árboles disponibles y muestra preferencia por la endémica Machaonia portorricensis. La orquídea prefiere árboles con cortezas lisas y alta capacidad de sostener agua y baja capacidad de retención de agua. Las condiciones microclimáticas bajo las cuáles los embriones entran a etapas pre-germinación reflejan los de la orquídea adulta, pero las condiciones bajo las cuáles los embriones llegan a etapas de germinación no. Lo que sugiere que los sitios de germinación adecuados no son necesariamente los lugares donde mejor se producirá; el desarrollo a etapas más avanzadas de la germinación....

Bone morphogenetic proteins (BMPs) are widely known for their ability to induce bone formation in development and/or when it has been some damage in bone tissue. Nonetheless, these proteins are also involved on many other processes and exert their functions in other tissues. The BMPs are recently study in cancer, possible therapy for repairing cardio vascular tissues and in regeneration process. Our lab focus the study on understanding the dynamics of regeneration process once there is loss or damaged to a tissue, to bring an insight of which are the mechanisms that ensure a complete regeneration. The phylum of Echinoderms possess impressive regenerative capacities, which makes them a great example of model systems to study and comprehend the regeneration process. Our model system, the Caribbean Sea cucumber Holothuria glaberrima helps us understand how the regeneration is accomplished since this echinoderm is able to regenerate most of its organs once they are eviscerated. Here we explore the functions of BMPs under the intestinal regeneration since previous studies in our lab prove that these proteins were present during this process. We used pharmacological agents to see how the BMPs played a role in the process of regeneration. Our results demonstrates that these proteins compromised the muscle cell dedifferentiation, cell proliferation and affect the variability of the blastema size during the intestinal regeneration....