Biology subjects

Alves-Lima, C.

Publications and source records attributed to Alves-Lima, C..

4 recordsLinked to original sources

bioRxiv2025

Evidence of local adaptation in threatened bull kelp (Nereocystis luetkeana) populations in Puget Sound

Stark declines in the abundance and distribution of bull kelp and reduced genetic diversity have been observed in Puget Sound, Washington, especially in southernmost areas. Consequently, introducing new variation through genetic rescue (GR) has emerged as a promising restoration strategy. However, GR success hinges on the preservation of local adaptation, which has not yet been studied in the region. To that end, we performed whole-genome sequencing on 100 gametophyte individuals from our biobank, sourced from 14 populations across Puget Sound. We identified three genetic clusters, corresponding broadly to southern Puget Sound (SPS), Whidbey Basin (WB), and the Strait of Juan de Fuca (SJF). Despite low genetic diversity and high genetic load, we found evidence of local adaptation to five environmental variables. Although salinity emerged as the strongest predictor of environmentally associated genetic variance overall, in SPS the primary drivers were average winter sea surface temperature (SST) and seasonal turbidity. We identified SNPs and enriched gene ontology (GO) terms and analyzed their allele frequencies to assess functional variation between clusters. These frequencies revealed marked differences between SJF and the other clusters, while for most genes, the highest-frequency allele in WB was also most prevalent in SPS. However, for all genes linked to winter SST and turbidity, SPS harbored distinct alleles not found in any other cluster. These findings suggest that a WB population would likely be a strong candidate donor for SPS due to its higher genetic diversity and shared adaptive variation. Further experiments are needed to validate these results and assess the suitability of WB populations for GR.

evolutionary biology↗

bioRxiv2025

SAMMBA is a high-throughput pipeline for isolating and phenotyping macroalgal strains

Anthropogenic climate change is causing the decline of seaweed forests in many parts of the world. Despite successful preservation efforts, their immense biodiversity is still severely underrepresented in germplasm biobanks throughout the world. These culture libraries can preserve genetic diversity and provide inoculum for marine forest restoration and mariculture ventures, and potentially accelerate the selection and breeding of climate-resilient and high-yielding strains. However, the complex life cycles and body plans of seaweeds pose a huge challenge for the development of standardized phenotyping and isolating protocols for microscopic stages, especially with the efficiency necessary to deal with the current pace of global climatic changes. Here, we present SAMMBA (Seaweed Automatable Microplate Microscopy for Breeding Approaches), an end-to-end pipeline for the high-throughput isolation, phenotyping and storage of macroalgal cells in 384-well plates (384WP). By optimizing fluorescence microscopy imaging and analysis, along with a novel fragmentation method and dilution-to-extinction isolation, different unialgal seaweed tissues could be regrown after thousand-fold dilutions. In a single plate, we successfully isolated 68 singlet gametophyte fragments of Laminaria ochroleuca (39 males, 29 females; 17.7% efficiency) and 60 spores of Phyllariopsis purpurascens (31.25% efficiency). Furthermore, the taxonomic versatility of SAMMBA was demonstrated through the successful isolation of 60 unialgal cultures of red algae (Halymenia sp., Hydrolithon sp., Erythrotrichia sp.) and 10 strains of the green alga Ulva sp, without cross-contamination. The viability and unialgal nature of the isolated strains were verified by distributing a single L. ochroleuca strain across an entire 384-well plate and imaging each well over 30 days. We found that the average specific daily growth rates (daily SGR) per well were 0.130 {+/-} 0.006 and 0.117 {+/-} 0.01 day-1 for males and females, respectively, showing a significant difference between sexes (n = 768; p = 1.27e-53), while edge effects significantly reduced daily SGR in males but not in females. This approach dramatically increases experimental reproducibility and statistical power compared to conventional methods. Due to its modular design and cost-effectiveness, SAMMBA is readily adaptable to macroalgal repositories globally. It supports high-throughput, selective recovery of unialgal strains without reliance on robotic platforms, while remaining fully compatible with automation. This system significantly expands the experimental and operational capacity in macroalgal hatcheries, providing a scalable foundation for phenomics, domestication programs, and standardized, verifiable biobanking of unialgal strains. Ultimately, SAMMBA could provide critical support for breeding strategies required to ensure the resilience of marine forests and aquaculture in a rapidly changing ocean.

plant biology↗

bioRxiv2025

The reference genome for the northeastern Pacific bull kelp, Nereocystis luetkeana

Bull kelp, Nereocystis luetkeana, is a northeastern Pacific kelp with broad distribution from Alaska to central California. Its population declines have caused severe concerns in northern California, the Salish Sea in Washington, and recently in some populations in Oregon. Despite bull kelps accumulated ecological and physiological studies, an assembled and annotated genomic reference was still unavailable. Here, we report the complete and annotated genome of Nereocystis luetkeana, produced by the California Conservation Genomics Project (CCGP), which aims to reveal genomic diversity patterns across California by sequencing the complete genomes of approximately 150 carefully selected species. The genome was assembled into 1,562 scaffolds with 449.82 Mb, 80x of coverage and 22,952 gene models. BUSCO assembly showed a completeness score of 72% for the stramenopiles gene set. The mitochondria and chloroplast genome sequences have 37 Mb and 131 Mb, respectively. The orthology analysis between 10 Phaeophycean genomes showed 1,065 expanded and 286 unique orthogroups for this species. Pairwise comparisons showed 542 orthogroups present only in N. luetkeana and M. pyrifera, another large-body kelp. The enrichment analysis of these orthogroups showed important functions related to central metabolism and signaling due to ATPases enrichment in these two species. This genome assembly will provide an essential resource for the ecology, evolution, conservation, and breeding of bull kelp.

genomics↗

bioRxiv2019

Rhythms of Transcription in Field-Grown Sugarcane Are Highly Organ Specific

We investigated whether different specialized organs in field-grown sugarcane follow the same temporal rhythms in transcription. We assayed the transcriptomes of three organs during the day: leaf, a source organ; internodes 1 and 2, sink organs focused on cell division and elongation; and internode 5, a sink organ focused on sucrose storage. The leaf had twice as many rhythmic transcripts (>68%) as internodes, and the rhythmic transcriptomes of the two internodes were more similar to each other than to those of the leaves. More transcripts were rhythmic under field conditions than under circadian conditions and most of their peaks were during the day. Among the transcripts that were considered expressed in all three organs, only 7.4% showed the same rhythmic time course pattern. The central oscillators of these three organs -- the networks that generate circadian rhythms -- had similar dynamics with different amplitudes. The differences between the rhythmic transcriptomes in circadian conditions and field conditions highlight the importance of field experiments to understand the plant circadian clock in natura. The highly specialized nature of the rhythmic transcriptomes in sugarcane organs probably arises from amplitude differences in tissue-specific circadian clocks and different sensitivities to environmental cues. One sentence summaryThe rhythmic transcriptome of field-grown sugarcane is highly organ-specific.

plant biology↗