Browsing by Issue Date, starting with "2024-11-12"
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- Enhancement of heat tolerance by salt stress in Tetraselmis striata CTP4: impacts on HSP gene expression, pigments, and proximal compositionPublication . Santos, Tamara; Pereira, Hugo; Maia, Inês Beatriz; Jacinto, Rita; Bombo, Gabriel; Ribeiro Pinheiro, Filipa Maria; Barreira, Luísa; Varela, JoãoAs the world average temperature is on the rise and heat waves are becoming more prevalent, microalgal producers have been facing significant challenges regarding the time periods during which they are able to grow less thermotolerant microalgae in outdoor production facilities. Therefore, it is urgent to explore how microalgae cope with thermal stress and under which growth conditions tolerance to temperatures close to or higher than their maximum thermal threshold is induced. For this purpose, Tetraselmis striata CTP4, a euryhaline microalga known for its thermotolerance, was selected. Tetraselmis striata belongs to the Chlorodendrophyceae, a clade that branched off early from other "core chlorophyte" clades, usually comprised of microalgae able to colonise freshwater habitats. Here, we present compelling evidence that the ability of this microalga to withstand otherwise lethal thermal upshifts to 40 degrees C is induced by exposure to higher salinity (35 ppt). In contrast, this response is abrogated at lower salinities. Concomitantly, the expression of genes encoding HSP70 and HSP100, two heat shock proteins known to mediate thermotolerance and tolerance to other stresses (e.g., salt stress) in fungi, animals and plants, was enhanced when exposed to both heat stress and higher salinities. This suggests that cross-protective mechanisms against abiotic stress appeared early during the evolution of the core chlorophytes and of Archaeplastida in general. This knowledge can be used to select novel strains and growth conditions that promote thermotolerance in microalgae that are grown in outdoor industrial production facilities in environments where heat waves are expected.
- Genome sequence of the marine alphaproteobacterium sp. EG35 isolated from the temperate octocoralPublication . Keller-Costa, Tina; Madureira, Selene; Fernandes, Ana S.; Kozma, Lydia; Gonçalves, Jorge Manuel Santos; Barroso, Cristina; Egas, Conceição; Costa, RodrigoWe report the genome sequence of sp. strain EG35 isolated from the octocoral sampled off the coast of Portugal. We reveal the coding potential for the biosynthesis of polyhydroxyalkanoates - biodegradable polyesters that may serve bioplastics production, diverse homoserine lactone-like communication signals, and four putatively novel natural products.
- Nesting biology of Green Sea turtles (Chelonia mydas), in Príncipe Island, Gulf of Guinea, Central AfricaPublication . Revés, Joana Filipa Silva; Patrício, Ana Rita; Vinagre, CatarinaThe green turtle (Chelonia mydas) hosts major nesting colonies in the Atlantic including São Tomé and Príncipe, where green sea turtles are the most common turtle species and Príncipe Island serves as a key nesting location. This rookery is known for exhibiting high genetic diversity, being an important genetic pool for the region. This study evaluated trends in the green turtle nesting population of Príncipe Island using data collected by Fundação Principe from 2015/16 until 2022/23 and data already published for Praia Grande from 2007/08 to 2014/15. Monitoring of sea turtle nesting activities occurs on all 36 nesting beaches from 1st September until the 30th of April and is divided into night and morning patrols during adult female and hatchling emergence. Green turtles followed a temporal distribution pattern that aligned with one of the dry periods (Gravaninha) and coincided with the nesting of São Tomé (August – March). Peaking between December and January, green turtles showed a preference for the eastern side of the island and a strong site fidelity. However, movements between nearby beaches were observed. Praia Grande and Praia Infante were the favourite nesting beaches, possessing ~ 80% of all nesting activity. 11,847 nests were monitored, with no significant increase in the nesting population, however, Praia Grande revealed consistent growth in nesting activity over 16 consecutive seasons, with a clutch frequency of 3.3 ± 1.8 clutches/season (range: 1-9). An estimated 884 nesting green turtle individuals was determined for the last three seasons, which revealed to be six times more than from the nesting seasons of 2007/08 – 2009/10. Long-term data analysis is still in need for determining definitive trends. Mean curved carapace lengths (99.4± 5.8 cm) of nesting females were smaller compared to other Atlantic populations, and similar to São Tomé. Clutch size (111 ± 22 eggs/clutch) also proved to be slightly lower from near green turtle populations and similar to São Tomé island’s average, likely due to the smaller size of nesting females. Hatching success was relatively high (88.9 ± 5.2%), but overestimations might have happened, since important data was missing like the percentage of ‘lost nests’ of the island, and detailed information of predation numbers. Predation was primarily made by dogs and tufted ghost crabs, remaining a significant threat to nesting success.