North Equatorial Current and Kuroshio Velocity Variations Affect Body Length and Distribution of the Japanese eel Anguilla japonica in Taiwan and Japan

The larval stage of Japanese eel travels a substantial distance over a long duration through the North Equatorial Current (NEC) and the Kuroshio, and the spawning behavior of mature eels leads to monthly arrival waves in eastern Taiwan between November and February. The total length (TL) of the glass eel relates to its larval duration and age; therefore, the TL can indicate the larval duration. The monthly mean TLs of eels along eastern Taiwan from 2010–2021 were used to estimate the batch age, and the recruitment patterns and relative abundances were compared. The TLs of glass eels followed a normal distribution, and the estimated ages were highly correlated with their mean TLs. Early recruit TLs were significantly greater than those of late recruits. The mean tracer drift time was longer in early recruitment months (November–December) than in later dates (February–March). The recruitment lag was approximately 1–1.5 months, with relative recruitment higher in the early recruitment months than in later months. Cohorts followed the main streams of the NEC and Kuroshio, and the monthly velocity changes of these currents could affect the TLs as well as the distribution patterns of Japanese glass eels in Taiwan and Japan.

Abstract MP221: Early Recruitment Of Neutrophils To The Ischemic Heart Is Orchestrated By Catecholamine-induced Demargination

Myocardial infarction (MI) induces a rapid and robust inflammatory response characterized by infiltration of different leukocyte cell types to the infarcted heart. Neutrophils are the first cells to arrive at the infarct where they release a plethora of proteolytic enzymes, exacerbate tissue injury, expand infarct size and promote cardiac dysfunction/ failure. We previously have shown that granulopoiesis (in the bone marrow, BM) is the major source of neutrophils during MI. However, the increase in the number of neutrophils at the infarct begins much earlier than the peak response in the BM (~ 24 hours) suggesting that sources other than granulopoiesis may contribute to the overall neutrophil pool. Because the marginated pool of neutrophils represents the same size of circulating pool, we hypothesized that demargination of neutrophils from the vascular wall contribute to the neutrophil burden in the heart, particularly during the early hours after MI.Using a mouse model of the permanent ligation of the left anterior descending coronary artery, BM ablation of hematopoietic stem cells, flow cytometry and BM transplant techniques, we found that the first wave of neutrophils recruited to the ischemic heart are exclusively sourced from the vasculature and not granulopoiesis in the BM/ spleen. The neutrophils recruited at the heart bore all hallmarks of demargination induced by dexamethasone including decreased F-actin, CD62L, and increased Adam17 expression. The recruitment of neutrophils is orchestrated by catecholamine stress as experimental strategies aimed at blockade of β1 and β2 adrenergic receptors (AR) reduced neutrophil burden in the ischemic heart. Interestingly, despite a decrease in neutrophil burden, the cardiac function did not improve but rather declined. However, short-term inhibition (6-12 hours post-MI) of β AR system either by receptor blockade (propranolol) or inhibition of catecholamine synthesis (AMPT) not only reduced neutrophil burden but also significantly improved cardiac function. Together these data suggest that catecholamine stress induced-demargination constitute the major source of neutrophils during the early hours post-MI. Pharmacological strategies aimed at suppressing the initial onslaught of neutrophils on the ischemic heart may represent a novel and viable approach towards a better resolution of the injury. Currently, studies are underway to define the signaling mechanisms that drive demargination and, to optimize the dose/ duration of a specific β receptor blocker to achieve better functional outcomes.

Analysis of gene network bifurcation during optic cup morphogenesis in zebrafish

Sight depends on the tight cooperation between photoreceptors and pigmented cells, which derive from common progenitors through the bifurcation of a single gene regulatory network into the neural retina (NR) and retinal-pigmented epithelium (RPE) programs. Although genetic studies have identified upstream nodes controlling these networks, their regulatory logic remains poorly investigated. Here, we characterize transcriptome dynamics and chromatin accessibility in segregating NR/RPE populations in zebrafish. We analyze cis-regulatory modules and enriched transcription factor motives to show extensive network redundancy and context-dependent activity. We identify downstream targets, highlighting an early recruitment of desmosomal genes in the flattening RPE and revealing Tead factors as upstream regulators. We investigate the RPE specification network dynamics to uncover an unexpected sequence of transcription factors recruitment, which is conserved in humans. This systematic interrogation of the NR/RPE bifurcation should improve both genetic counseling for eye disorders and hiPSCs-to-RPE differentiation protocols for cell-replacement therapies in degenerative diseases.

Jackfruit trees as seed attractors and nurses of early recruitment of native plant species in a secondary forest in Brazil.

The Atlantic Forest is one of the most threatened tropical forests in the world, being drastically reduced, fragmented and disturbed. The drastic process of anthropic occupation and exploitation of this biome has, in many cases, led to the introduction of exotic species, such as the jackfruits (Artocarpus heterophyllus). However, studies on the influence of jackfruits on the native biota are still scarce. Here we investigated the influence of fruit trees on the seed rain and early recruitment of seedlings in native remnants, comparing these patterns with those observed for a native species tapirira (Tapirira guianensis), which similarly to jackfruits, produces many fruits thruought the year, attracting a variety of frugivore species. Seed rain and seedlings observed under the jackfruits were both more abundant and equally rich to the assemblages reported under the native tapirira trees. In both species, co-specifics comprise a large part of the number of seeds (> 70%) and seedlings (> 45%) individuals and, although they attract similar seed assemblages, seedling composition diverge, particularly when co-specifics are excluded. We reported that jackfruits can attract a diverse seed and seedling assemblages, and we find no evidence that the presence of jackfruits negatively affects the arrival and initial recruitment of native plant species in the study area. These results should be analysed with caution but considered when evaluating costs and benefits of management options to control exotic species.

Dystrophin Deficiency Causes Progressive Depletion of Cardiovascular Progenitor Cells in the Heart

Duchenne muscular dystrophy (DMD) is a devastating condition shortening the lifespan of young men. DMD patients suffer from age-related dilated cardiomyopathy (DCM) that leads to heart failure. Several molecular mechanisms leading to cardiomyocyte death in DMD have been described. However, the pathological progression of DMD-associated DCM remains unclear. In skeletal muscle, a dramatic decrease in stem cells, so-called satellite cells, has been shown in DMD patients. Whether similar dysfunction occurs with cardiac muscle cardiovascular progenitor cells (CVPCs) in DMD remains to be explored. We hypothesized that the number of CVPCs decreases in the dystrophin-deficient heart with age and disease state, contributing to DCM progression. We used the dystrophin-deficient mouse model (mdx) to investigate age-dependent CVPC properties. Using quantitative PCR, flow cytometry, speckle tracking echocardiography, and immunofluorescence, we revealed that young mdx mice exhibit elevated CVPCs. We observed a rapid age-related CVPC depletion, coinciding with the progressive onset of cardiac dysfunction. Moreover, mdx CVPCs displayed increased DNA damage, suggesting impaired cardiac muscle homeostasis. Overall, our results identify the early recruitment of CVPCs in dystrophic hearts and their fast depletion with ageing. This latter depletion may participate in the fibrosis development and the acceleration onset of the cardiomyopathy.