The Effect of Hearing Loss and Working Memory Capacity on Context Use and Reliance on Context in Older Adults.

OBJECTIVES: Older adults often complain of difficulty in communicating in noisy environments. Contextual information is considered an important cue for identifying everyday speech. To date, it has not been clear exactly how context use (CU) and reliance on context in older adults are affected by hearing status and cognitive function. The present study examined the effects of semantic context on the performance of speech recognition, recall, perceived listening effort (LE), and noise tolerance, and further explored the impacts of hearing loss and working memory capacity on CU and reliance on context among older adults. DESIGN: Fifty older adults with normal hearing and 56 older adults with mild-to-moderate hearing loss between the ages of 60 and 95 years participated in this study. A median split of the backward digit span further classified the participants into high working memory (HWM) and low working memory (LWM) capacity groups. Each participant performed high- and low-context Repeat and Recall tests, including a sentence repeat and delayed recall task, subjective assessments of LE, and tolerable time under seven signal to noise ratios (SNRs). CU was calculated as the difference between high- and low-context sentences for each outcome measure. The proportion of context use (PCU) in high-context performance was taken as the reliance on context to explain the degree to which participants relied on context when they repeated and recalled high-context sentences. RESULTS: Semantic context helps improve the performance of speech recognition and delayed recall, reduces perceived LE, and prolongs noise tolerance in older adults with and without hearing loss. In addition, the adverse effects of hearing loss on the performance of repeat tasks were more pronounced in low context than in high context, whereas the effects on recall tasks and noise tolerance time were more significant in high context than in low context. Compared with other tasks, the CU and PCU in repeat tasks were more affected by listening status and working memory capacity. In the repeat phase, hearing loss increased older adults' reliance on the context of a relatively challenging listening environment, as shown by the fact that when the SNR was 0 and -5 dB, the PCU (repeat) of the hearing loss group was significantly greater than that of the normal-hearing group, whereas there was no significant difference between the two hearing groups under the remaining SNRs. In addition, older adults with LWM had significantly greater CU and PCU in repeat tasks than those with HWM, especially at SNRs with moderate task demands. CONCLUSIONS: Taken together, semantic context not only improved speech perception intelligibility but also released cognitive resources for memory encoding in older adults. Mild-to-moderate hearing loss and LWM capacity in older adults significantly increased the use and reliance on semantic context, which was also modulated by the level of SNR.

SeMet alleviates AFB1-induced oxidative stress and apoptosis in rabbit kidney by regulating Nrf2//Keap1/NQO1 and PI3K/AKT signaling pathways.

The purpose of this study was to explore the protective effect of SeMet on renal injury induced by AFB1 in rabbits and its molecular mechanism. Forty rabbits of 35 days old were randomly divided into control group, AFB1 group (0.3 mg AFB1/kg b.w), 0.2 mg/kg Se + AFB1 group (0.3 mg AFB1/kg b.w + 0.2 mg SeMet/kg feed) and 0.4 mg/kg Se + AFB1 group (0.3 mg AFB1/kg b.w + 0.4 mg SeMet/kg feed). The SeMet treatment group was fed different doses of SeMet diets every day for 21 days. On the 17-21 day, the AFB1 treatment group, the 0.2 mg/kg Se + AFB1 group and the 0.4 mg/kg Se + AFB1 group were administered 0.3 mg AFB1 /kg b.w by gavage (dissolved in 0.5 ml olive oil) respectively. The results showed that AFB1 poisoning resulted in the changes of renal structure, the increase of renal coefficient and serum biochemical indexes, the ascent of ROS and MDA levels, the descent of antioxidant enzyme activity, and the significant down-regulation of Nrf2, HO-1 and NQO1. Besides, AFB1 poisoning increased the number of renal apoptotic cells, rised the levels of PTEN, Bax, Caspase-3 and Caspase-9, and decreased the levels of PI3K, AKT, p-AKT and Bcl-2. In summary, SeMet was added to alleviate the oxidative stress injury and apoptosis of kidney induced by AFB1, and the effect of 0.2 mg/kg Se + AFB1 is better than 0.4 mg/kg Se + AFB1.

Differential auditory cortical development in left and right cochlear implanted children.

Unilateral aural stimulation has been shown to cause massive cortical reorganization in brain with congenital deafness, particularly during the sensitive period of brain development. However, it is unclear which side of stimulation provides most advantages for auditory development. The left hemisphere dominance of speech and linguistic processing in normal hearing adult brain has led to the assumption of functional and developmental advantages of right over left implantation, but existing evidence is controversial. To test this assumption and provide evidence for clinical choice, we examined 34 prelingually deaf children with unilateral cochlear implants using near-infrared spectroscopy. While controlling for age of implantation, residual hearing, and dominant hand, cortical processing of speech showed neither developmental progress nor influence of implantation side weeks to months after implant activation. In sharp contrast, for nonspeech (music signal vs. noise) processing, left implantation showed functional advantages over right implantation that were not yet discernable using clinical, questionnaire-based outcome measures. These findings support the notion that the right hemisphere develops earlier and is better preserved from adverse environmental influences than its left counterpart. This study thus provides, to our knowledge, the first evidence for differential influences of left and right auditory peripheral stimulation on early cortical development of the human brain.

Chitosan Microspheres Loaded with Curcumin and Gallic Acid: Modified Synthesis, Sustainable Slow Release, and Enhanced Biological Property.

Improving the utilization rate of loaded-drugs is of huge importance for generating chitosan-based (CS) micro-carriers. This study aims to fabricate a novel CS microspheres co-delivered curcumin (Cur) and gallic acid (Ga) to assess drug loading and release kinetics, the blood compatibility and anti-osteosarcoma properties. The present study observes the interaction between CS and Cur/Ga molecules and estimates the change in crystallinity and loading and release rate. In addition, blood compatibility and cytotoxicity of such microspheres are also evaluated. Cur-Ga-CS microspheres present high entrapment rate of (55.84 ± 0.34) % for Ga and (42.68 ± 0.11) % for Cur, possibly attributed to surface positive charge (21.76 ± 2.46) mV. Strikingly, Cur-Ga-CS microspheres exhibit slowly sustainable release for almost 7 days in physiological buffer. Importantly, these microspheres possess negligibly toxic to blood and normal BMSC cells, but strong anti-osteosarcoma effect on U2OS cells. Overall, Cur-Ga-CS microspheres are promising to become a novel anti-osteosarcoma agent or sustainable delivery carrier in biomedical applications.

Selenomethionine attenuates ochratoxin A-induced small intestinal injury in rabbits by activating the Nrf2 pathway and inhibiting NF-κB activation.

The aim of this study was to investigate whether selenomethionine (SeMet) could attenuate intestinal injury in rabbits induced by ochratoxin A (OTA). Sixty 35-day-old IRA rabbits with similar weights were randomly assigned to the control group, OTA group (0.2 mg OTA/kg b.w), OTA+ 0.2 mg/kg Se (0.2 mg OTA/kg b.w + 0.2 mg SeMet/kg feed), OTA+ 0.4 mg/kg Se (0.2 mg OTA/kg b.w + 0.4 mg SeMet/kg feed) and OTA+ 0.6 mg/kg Se (0.2 mg OTA/kg b.w + 0.6 mg SeMet/kg feed). The rabbits were examined after oral administration of different doses of SeMet for 21 days and were intragastrically administered OTA for 7 consecutive days. The results showed that pretreatment with different doses of SeMet protected against the changes in serum biochemical indicators and the decline in production performance caused by OTA exposure. In addition, the activities of SOD, GSH-PX and T-AOC were significantly increased, and the levels of MDA and ROS were decreased after SeMet pretreatment; thus, oxidative damage in rabbit jejunum tissue due to OTA exposure was inhibited. SeMet stimulates Nrf2 and inhibits the NF-κB signalling pathway; the anti-inflammatory response and antioxidative stress in rabbits were improved, and the intestinal barrier damage caused by OTA exposure was improved. In summary, SeMet alleviates OTA-induced intestinal toxicity in rabbits by activating the Nrf2 pathway and inhibiting NF-κB activation. Moreover, 0.4 mg/kg SeMet induced the most significant improvement.

Functional antibody characterization via direct structural analysis and information-driven protein-protein docking.

Detailed description of the mechanism of action of the therapeutic antibodies is essential for the functional characterization and future optimization of potential clinical agents. We recently developed KD035, a fully human antibody targeting vascular endothelial growth factor receptor 2 (VEGFR2). KD035 blocked VEGF-A, and VEGF-C-mediated VEGFR2 activation, as demonstrated by the in vitro binding and competition assays and functional cellular assays. Here, we report a computational model of the complex between the variable fragment of KD035 (KD035(Fv)) and the domains 2 and 3 of the extracellular portion of VEGFR2 (VEGFR2(D2-3)). Our modeling was guided by a priori experimental information including the X-ray structures of KD035 and related antibodies, binding assays, target domain mapping and comparison of KD035 affinity for VEGFR2 from different species. The accuracy of the model was assessed by molecular dynamics simulations, and subsequently validated by mutagenesis and binding analysis. Importantly, the steps followed during the generation of this model can set a precedent for future in silico efforts aimed at the accurate description of the antibody-antigen and more broadly protein-protein complexes.

Ultramicroporous Organophosphorus Polymers via Self-Accelerating P-C Coupling Reactions: Kinetic Effects on Crosslinking Environments and Porous Structures.

Porous organic polymers (POPs) have drawn significant attention in diverse applications. However, factors affecting the heterogeneous polymerization and porosity of POPs are still not well understood. Herein, we report a new strategy to construct porous organophosphorus polymers (POPPs) with high surface areas (1283 m2/g) and ultramicroporous structures (0.67 nm). The strategy harnesses an efficient transition-metal-catalyzed phosphorus-carbon (P-C) coupling reaction at the trigonal pyramidal P-center, which is distinct from the typical carbon-carbon coupling reaction utilized in the synthesis of POPs. As the first kinetic study on the coupling reaction of POPs, we uncovered a self-accelerating reaction characteristic, which is controlled by the choice of bases and catalysts. The self-accelerating characteristic of the P-C coupling reaction is beneficial for the high surface area and uniform ultramicroporosity of POPPs. The direct crosslinking of the P-centers allows 31P solid-state (ss)NMR experiments to unambiguously reveal the crosslinking environments of POPPs. Leveraging on the kinetic studies and 31P ssNMR studies, we were able to reveal the kinetic effects of the P-C coupling reaction on both the crosslinking environments and the porous structures of POPPs. Furthermore, our studies show that the CO2 uptake capacity of POPPs is highly dependent on their porous structures. Overall, our studies paves the way to design new POPs with better controlled chemical and ultramicroporous structures, which have potential applications for CO2 capture and separation.

hsa-miR-875-5p inhibits tumorigenesis and suppresses TGF-ß signalling by targeting USF2 in gastric cancer.

BACKGROUND: Gastric cancer (GC) is one of the most common malignancies, and an increasing number of studies have shown that its pathogenesis is regulated by various miRNAs. In this study, we investigated the role of miR-875-5p in GC. METHODS: The expression of miR-875-5p was detected in human GC specimens and cell lines by miRNA qRT-PCR. The effect of miR-875-5p on GC proliferation was determined by Cell Counting Kit-8 (CCK-8) proliferation and 5-ethynyl-2'-deoxyuridine (EdU) assays. Migration and invasion were examined by transwell migration and invasion assays as well as wound healing assays. The interaction between miR-875-5p and its target gene upstream stimulatory factor 2(USF2) was verified by dual luciferase reporter assays. The effects of miR-875-5p in vivo were studied in xenograft nude mouse models. Related proteins were detected by western blot. RESULTS: The results showed that miR-875-5p inhibited the proliferation, migration and invasion of GC cells in vitro and inhibited tumorigenesis in vivo. USF2 was proved to be a direct target of miR-875-5p. Knockdown of USF2 partially counteracted the effects of miR-875-5p inhibitor. Overexpression of miR-875-5p could inhibit proliferation, migration and invasion and suppress the TGF-ß signalling pathway by downregulating USF2. CONCLUSIONS: MiR-875-5p can inhibit the progression of GC by directly targeting USF2. And in the future, miR-875-5p is expected to be a potential target for GC diagnosis and treatment.

Voice Emotion Recognition by Mandarin-Speaking Children with Cochlear Implants.

OBJECTIVES: Emotional expressions are very important in social interactions. Children with cochlear implants can have voice emotion recognition deficits due to device limitations. Mandarin-speaking children with cochlear implants may face greater challenges than those speaking nontonal languages; the pitch information is not well preserved in cochlear implants, and such children could benefit from child-directed speech, which carries more exaggerated distinctive acoustic cues for different emotions. This study investigated voice emotion recognition, using both adult-directed and child-directed materials, in Mandarin-speaking children with cochlear implants compared with normal hearing peers. The authors hypothesized that both the children with cochlear implants and those with normal hearing would perform better with child-directed materials than with adult-directed materials. DESIGN: Thirty children (7.17-17 years of age) with cochlear implants and 27 children with normal hearing (6.92-17.08 years of age) were recruited in this study. Participants completed a nonverbal reasoning test, speech recognition tests, and a voice emotion recognition task. Children with cochlear implants over the age of 10 years also completed the Chinese version of the Nijmegen Cochlear Implant Questionnaire to evaluate the health-related quality of life. The voice emotion recognition task was a five-alternative, forced-choice paradigm, which contains sentences spoken with five emotions (happy, angry, sad, scared, and neutral) in a child-directed or adult-directed manner. RESULTS: Acoustic analyses showed substantial variations across emotions in all materials, mainly on measures of mean fundamental frequency and fundamental frequency range. Mandarin-speaking children with cochlear implants displayed a significantly poorer performance than normal hearing peers in voice emotion perception tasks, regardless of whether the performance is measured in accuracy scores, Hu value, or reaction time. Children with cochlear implants and children with normal hearing were mainly affected by the mean fundamental frequency in speech emotion recognition tasks. Chronological age had a significant effect on speech emotion recognition in children with normal hearing; however, there was no significant correlation between chronological age and accuracy scores in speech emotion recognition in children with implants. Significant effects of specific emotion and test materials (better performance with child-directed materials) in both groups of children were observed. Among the children with cochlear implants, age at implantation, percentage scores of nonverbal intelligence quotient test, and sentence recognition threshold in quiet could predict recognition performance in both accuracy scores and Hu values. Time wearing cochlear implant could predict reaction time in emotion perception tasks among children with cochlear implants. No correlation was observed between the accuracy score in voice emotion perception and the self-reported scores of health-related quality of life; however, the latter were significantly correlated with speech recognition skills among Mandarin-speaking children with cochlear implants. CONCLUSIONS: Mandarin-speaking children with cochlear implants could have significant deficits in voice emotion recognition tasks compared with their normally hearing peers and can benefit from the exaggerated prosody of child-directed speech. The effects of age at cochlear implantation, speech and language development, and cognition could play an important role in voice emotion perception by Mandarin-speaking children with cochlear implants.

Effects of a Shift of the Signal Peptide Cleavage Site in Signal Peptide Variant on the Synthesis and Secretion of SARS-CoV-2 Spike Protein.

The COVID-19 pandemic is caused by SARS-CoV-2; the spike protein is a key structural protein that mediates infection of the host by SARS-CoV-2. In this study, we aimed to evaluate the effects of signal peptide on the secretion and release of SARS-CoV-2 spike protein. Therefore, we constructed a signal peptide deletion mutant and three signal peptide site-directed mutants. The (H) region and (C) region in the signal peptide of L5F-S13I mutant have changed significantly, compared with wild type, L5F and S13I. We demonstrated the effects of signal peptide on the secretion and synthesis of RBD protein, finding that mutation of S13 to I13 on the signal peptide is more conducive to the secretion of RBD protein, which was mainly due to the shift of the signal peptide cleavage site in the mutant S13I. Here, we not only investigated the structure of the N-terminal signal peptide of the SARS-CoV-2 spike protein but also considered possible secretory pathways. We suggest that the development of drugs that target the signal peptide of the SARS-CoV-2 spike protein may have potential to treat COVID-19 in the future.

Na2S-Mediated One-Pot Selective Deoxygenation of α-Hydroxyl Carbonyl Compounds including Natural Products.

A practical method for the deoxygenation of α-hydroxyl carbonyl compounds under mild reaction conditions is reported here. The use of cheap and easy-to-handle Na2S·9H2O as the reductant in the presence of PPh3 and N-chlorosuccinimide (NCS) enables the selective dehydroxylation of α-hydroxyl carbonyl compounds, including ketones, esters, amides, imides and nitrile groups. The synthetic utility is demonstrated by the late-stage deoxygenation of bioactive molecule and complex natural products.

Release of Leu-Pro-Pro from corn gluten meal by fermentation with a Lactobacillus helveticus strain.

BACKGROUND: Angiotensin-converting enzyme (ACE) inhibitory peptides are potential alternatives to the synthetic ACE inhibitory drugs, but the in vivo antihypertensive effects of most of them have not been confirmed. The tripeptide Leu-Pro-Pro (LPP) is one of the few peptides that have been proved clinically effective in reducing the blood pressure of hypertensive patients and casein is currently its major source. LPP is contained in multiple fractions of zein, and corn gluten meal (CGM) is hence a potential new source of LPP. For this purpose, CGM was fermented with a Lactobacillus helveticus strain and the medium composition was optimized; the decoloration of the resultant hydrolysate was investigated as well. RESULTS: LPP could be successfully released from CGM by fermentation with the strain Lactobacillus helveticus CICC 22536. The highest LPP content and protein recovery of 561 mg kg-1 and 14.92% occurred in the medium containing 20 g L-1 glucose, 15 g L-1 beef extract, 60 g L-1 CGM, 10 g L-1 CaCO3 , 0.5 g L-1 NaCl, and inoculation amount 6%. The supplementation of Flavourzyme® further improved the two parameters to 662 mg kg-1 and 36.94%, respectively. The permeate of the hydrolysate after ultrafiltration through a 5 kDa membrane could be effectively decolored by the macroporous resin XAD-16 without notable protein loss, and its LPP content was further boosted to 743 mg kg-1 . CONCLUSION: CGM is a potential new source of LPP and its ultrafiltered and decolored hydrolysate could be used to develop new antihypertensive functional foods. © 2021 Society of Chemical Industry.

Excited-state engineering of oligothiophenes via phosphorus chemistry towards strong fluorescent materials.

Due to efficient intersystem crossing (ISC), combined with efficient non-radiative processes of the triplet excited state, oligothiophenes generally exhibit very weak photoluminescence. Phosphorus (P)-bridged terthiophenes (P-terThs) and phosphorus (P)-bridged bithiophenes (P-biThs) were synthesized. The diverse and well-defined P-chemistry has been applied to fine tune the photophysical properties of these materials. The asymmetric electronic coupling between the P-center and terThs suppressed the electronic interactions of two terTh and biTh moieties in the ground state S0. Particularly, P-terThs and P-biThs having a positively charged P(+)-center induce pronounced asymmetric electronic environments on the two terThs and two biThs, respectively, which allows relaxation from the initial excited state via symmetry breaking charge transfer (SBCT) to give the charge separated state SSBCT. P-terThs and P-biThs having a positively charged P(+)-center exhibit stronger SBCT than others, which may result in a weaker ISC of oligothiophenes, and consequently lead to the photoluminescence quantum yields (PLQYs) being as high as 71% and 39%, respectively. The current study uncovered detailed insights on the effects of phosphorus chemistry on the SBCT of oligothiophenes and their resulting effects on the photophysical properties of P-bridged oligothiophenes, which have not been previously addressed in oligothiophenes.

Interaction and Kinetics Study of the Co-Gasification of High-solid Anaerobic Digestate and Lignite.

This study aims at investigating the interaction and kinetics behavior of the co-gasification of digestate and lignite. The co-pyrolysis performances of digestate and lignite blended by dry process were better than that blended by wet process, while the wet-blending process could improve the performance in co-gasification stage because of the larger pore diameter and pore volume. When anaerobic digestion (AD) time was 40 days, the synergistic interaction between digestate and lignite were the most remarkable based on the results of thermogravimetric analysis (TG) and the experiments in the lab-scale downdraft fixed bed gasifier. Kinetics study showed that the increase of AD time and the addition of digestate in lignite decreased the activation energy of the co-gasification reaction.

A Convenient Fluorescence-Based Assay for the Detection of Sucrose Transport and the Introduction of a Sucrose Transporter from Potato into Clostridium Strains.

A convenient and effective sucrose transport assay for Clostridium strains is needed. Traditional methods, such as 14C-sucrose isotope labelling, use radioactive materials and are not convenient for many laboratories. Here, a sucrose transporter from potato was introduced into Clostridium, and a fluorescence assay based on esculin was used for the analysis of sucrose transport in Clostridium strains. This showed that the heterologously expressed potato sucrose transporter is functional in Clostridium. Recombinant engineering of high-level sucrose transport would aid sucrose fermentation in Clostridium strains. The assay described herein provides an important technological platform for studying sucrose transporter function following heterologous expression in Clostridium.

[Expression and characterization of a neutral Enterobacter cloacae GX-3 invertase].

OBJECTIVE: To characterize a neutral invertase from Enterobacter cloacae GX-3. METHODS: By searching GenBank database, we found the genes encoding invertase from the same genus Enterobacter. These sequences were aligned and analyzed. Then, a gene encoding neutral invertase was amplified by PCR. The recombinant plasmid pQE-Einv was constructed. We purified the expressed protein Einv with nickel-nitrilotriacetic acid chromatography. At last, the characterics of the recombinant protein Einv were studied in detail. RESULTS: A gene encoding neutral invertase was discovered and cloned from E. cloacae GX-3. The recombinant enzyme Einv was characterized. Einv had an optimum pH of 6.5 and an optimum temperature of 40 degrees C. The results of sodium dodecyl sulfate polyacrylamide gel electropheresis (SDS-PAGE) and gel permeation chromatography ( GPC) showed that Einv was a homo-dimer protein. Einv retained 80% activity at sucrose concentrations up to 1170 mmol/L. But, Einv had no transglycosylation activity at high sucrose concentration. It could hydrolyze raffinose, 1-kestose, nystose, fructofuranosylnystose and stachyose. CONCLUSION: It is first reported that an invertase from Enterobacter cloacae is a beta-fructofuranosidase at neutral pH range. It only has hydrolysis activity without tranglycosylation activity. These characteristics indicate that the neutral invertase Einv has important applications in food industry.

Diversity of Francisella tularensis subsp. holarctica lineages, China.

We analyzed 10 isolates of Francisella tularensis subspecies holarctica from China and assigned them to known clades by using canonical single-nucleotide polymorphisms. We found 4 diverse subtypes, including 3 from the most basal lineage, biovar japonica. This result indicates unprecedented levels of diversity from a single region and suggests new models for emergence.

Impact of pretreatment on solid state anaerobic digestion of yard waste for biogas production.

Solid state anaerobic digestion, as a safe and environment-friendly technology to dispose municipal solid wastes, can produce methane and reduce the volume of wastes. In order to raise the digestion efficiency, this study investigated the pretreatment of yard waste by thermal or chemical method to break down the complex lignocellulosic structure. The composition and structure of pretreated yard waste were analyzed and characterized. The results showed that the pretreatment decreased the content of cellulose and hemicelluloses in yard waste and in turn improved the hydrolysis and methanogenic processes. The thermal pretreatment sample (P1) had the highest methane yield, by increasing 88% in comparison with digesting the raw material. The maximum biogas production reached 253 mL/g volatile solids (VS). The largest substrate mass reduction was obtained by the alkaline pretreatment (P5). The VS of the alkaline-treated sample decreased about 60% in comparison with the raw material.

Factors Affecting Visual-Only Speech Recognition in Individuals With Cochlear Implants.

Objectives: Several reports have underlined the benefits of speechreading (visual-only speech recognition) on speech recognition in individuals with hearing loss after cochlear implantation (CI). However, the factors that would affect the ability of speechreading are unclear. The aim of the present study is to assess the factors that affect speechreading abilities in CI users. Methods: A total of 104 participants were enrolled in this retrospective study. They viewed silent videos of sentences being spoken by a model and were tasked with repeating what they thought had been said. They were tested under audio-only and visual-only conditions. Factors (such as the age, the age of CI; <3 years old vs 3-8 years old; male vs female, etc) believed to affect speechreading abilities were analyzed. Results: The age range of the participants is 8 to 34 years. CI users showed significantly different speechreading abilities among themselves. The authors found that age and hearing loss at 3 to 8 years of age were positively related to superior speechreading recognition scores. Conclusions: CI users followed a more complex method of perceptual compensation. Those who have suffered hearing loss between 3 and 8 years of age are more sensitive to developing an advantage in speech recognition by using speechreading. Older age positively affects speechreading abilities; thus, the more experience CI has, the greater speechreading ability they may exhibit.

Continuously tunable separation of light-induced Haematococcus pluvialis using an ultrastretchable, sheath-flow-assisted elasto-inertial microchannel.

BACKGROUND: A proportion of Haematococcus pluvialis under the light stress can effectively conduct astaxanthin biosynthesis, leading to the increase in cell size. Although the size is a critical indicator for identifying the astaxanthin-rich H. pluvialis cells, the cut-off size to be separated varies from sample to sample. RESULTS: Here, we report an ultrastretchable, straight elasto-inertial microchannel with tunable separation threshold to continuously separate the light-induced H. pluvialis cells by size. The symmetrical sheath flows confine the particles to the channel sidewalls, and large particles can cross the interface of viscoelastic fluids to the equilibrium position at the channel centerline. By stretching the microfluidic chip, the medium-sized particles can gradually migrate to the channel centerline in the narrower and longer channel, bringing the tunable separation threshold. Results show that the separation performance of the ultrastretchable microfluidic device is affected by total flow rate, flow rate ratio of sheath to sample, polyethylene oxide (PEO) solution configuration. Lastly, size-tunable separation of light-induced H. pluvialis cells is demonstrated. SIGNIFICANCE: To the best of our knowledge, this is the first report on cell migration in co-flow configurations in the ultra-stretchable microfluidics. Separation of H. pluvialis is not only a relevant end application in harvesting the astaxanthin-rich species, but the separated populations of highly productive microalgal cells will open a venue for cellular directed evolution.