Knockdown of CPT1A Induce Chicken Adipocyte Differentiation to Form Lipid Droplets

Lipid metabolism dysfunction is closely related to obesity, inflammation, diabetes, lipodystrophy, cardiovascular disease. Along with having a positive effect on energy homeostasis during fasting or prolonged exercise through mitochondrial fatty acid oxidation (FAO), more than two dozen enzymes and transport proteins are involved in the activation and transport of fatty acids into the mitochondrial, providing insights into their critical roles in metabolism. CPT1A has been reported to be expressed ubiquitously in the body and associated with dire consequences affecting fat deposition as the key rate-limiting enzyme of FAO. However, there is a dearth of data on the specific role of CPT1A on adipogenic differentiation and adipocyte lipolysis on chicken. This study assessed CPT1A's function in adipocyte differentiation andadipocyte lipolysis, and the mechanisms were investigated. We found that CPT1A knockdown (KD) promotes the differentiation of chicken preadipocytes into mature adipocytes. CPT1A KD increased PPARγ protein expression level. Expression levels of lipid synthesis-related genes were increased, and lipolysis genes were reduced. Also, CPT1A KD can encourage the formation of lipid droplets. So our results confirmed that knockdown of CPT1A induced the lipid differentiation and inhibited the ß-oxidation process to promote the formation of lipid droplets. These findings may deepen our understanding on CPT1A function, especially its regulatory role in adipocyte biology.(AU)

Mfsd2a Promotes the Proliferation, Migration, Differentiation and Adipogenesis of Chicken Intramuscular Preadipocytes

Intramuscular fat (IMF) content is a crucial parameter for estimating meat quality. Growing evidence indicates that gene regulation plays an important role in IMF deposition. This study aimed to determine the function of Mfsd2a in chicken intramuscular preadipocytes. In the present study, high Mfsd2a mRNA levels were observed in the liver and adipose tissues of broilers. Subsequently, we synthesized small interfering RNAs to silence the expression of Mfsd2a in chicken intramuscular preadipocytes. The following results suggested that CDK2, PCNA, CCND1, CCND2 and MKI67 were inhibited, with CCK-8 and EdU assays revealing that cell proliferation was inhibited. Scratch test showed that cell migration ratios were declined. We also found that Mfsd2a silencing decreased the mRNA levels of PPARγ, RXRG and their target genes. The similar results were found in some key genes that contribute to lipid synthesis, including C/EBPα, C/EBPß, FABP4, FASN, ACACA and ACSL1. Finally, Oil red O staining showed that IMF accumulation was blocked after Mfsd2a silencing. In conclusion, our results implied that Mfsd2a promotes the proliferation and migration of chicken intramuscular preadipocytes, as well as the differentiation and adipogenesis through PPARγ signaling pathway, which may provide a potential target to improve chicken meat quality.(AU)

Genome-wide scanning for CHD1L gene in papillary thyroid carcinoma complicated with type 2 diabetes mellitus.

PURPOSE: Papillary thyroid carcinoma (PTC) represents the most common subtype of thyroid cancer (TC). This study was set out to explore the potential effect of CHD1L on PTC and type 2 diabetes mellitus (T2DM). METHODS: We searched for T2DM susceptibility genes through the GWAS database and obtained T2DM-related differentially expressed gene from the GEO database. The expression and clinical data of TC and normal samples were collated from the TCGA database. Receiver operating characteristic (ROC) curve analysis was subsequently applied to assess the sensitivity and specificity of the CHD1L for the diagnosis of PTC. The MCP-counter package in R language was then utilized to generate immune cell score to evaluate the relationship between CHD1L expression and immune cells. Then, we performed functional enrichment analysis of co-expressed genes and DEGs to determine significantly enriched GO terms and KEGG to predict the potential functions of CHD1L in PTC samples and T2DM adipose tissue. RESULTS: From two genes (ABCB9, CHD1L) were identified to be DEGs (p < 1 * 10-5) that exerted effects on survival (HR > 1, p < 0.05) in PTC and served as T2DM susceptibility genes. The gene expression matrix-based scoring of immunocytes suggested that PTC samples with high and low CHD1L expression presented with significant differences in the tumor microenvironment (TME). The enrichment analysis of CHD1L co-expressed genes and DEGs suggested that CHD1L was involved in multiple pathways to regulate the development of PTC. Among them, Kaposi sarcoma-associated herpesvirus infection, salmonella infection and TNF signaling pathways were highlighted as the three most relevant pathways. GSEA analysis, employed to analyze the genome dataset of PTC samples and T2DM adipose tissue presenting with high and low expression groups of CHD1L, suggests that these differential genes are related to chemokine signaling pathway, leukocyte transendothelial migration and TCELL receptor signaling pathway. CONCLUSION: CHD1L may potentially serve as an early diagnostic biomarker for PTC, and a target of immunotherapy for PTC and T2DM.

Enhanced shoot investment makes invasive plants exhibit growth advantages in high nitrogen conditions / O investimento de tiro aumentado faz plantas invasivas exposição de vantagens de crescimento em altas condições de nitrógeno

Abstract Resource amendments commonly promote plant invasions, raising concerns over the potential consequences of nitrogen (N) deposition; however, it is unclear whether invaders will benefit from N deposition more than natives. Growth is among the most fundamental inherent traits of plants and thus good invaders may have superior growth advantages in response to resource amendments. We compared the growth and allocation between invasive and native plants in different N regimes including controls (ambient N concentrations). We found that invasive plants always grew much larger than native plants in varying N conditions, regardless of growth- or phylogeny-based analyses, and that the former allocated more biomass to shoots than the latter. Although N addition enhanced the growth of invasive plants, this enhancement did not increase with increasing N addition. Across invasive and native species, changes in shoot biomass allocation were positively correlated with changes in whole-plant biomass; and the slope of this relationship was greater in invasive plants than native plants. These findings suggest that enhanced shoot investment makes invasive plants retain a growth advantage in high N conditions relative to natives, and also highlight that future N deposition may increase the risks of plant invasions.

Resumo As alterações de recursos geralmente promovem invasões de plantas, suscitando preocupações quanto às conseqüências potenciais da deposição de nitrogênio (N); No entanto, não está claro se os invasores se beneficiarão da deposição de N mais do que com os nativos. O crescimento é um dos traços inerentes mais fundamentais das plantas e, portanto, os bons invasores podem ter vantagens de crescimento superiores em resposta a alterações de recursos. Comparamos o crescimento e a alocação entre plantas invasivas e nativas em diferentes regimes de N, incluindo controles (concentrações ambientais de N). Descobrimos que as plantas invasivas sempre cresceram muito mais do que as plantas nativas em diferentes condições de N, independentemente das análises baseadas em crescimento ou filogenia, e que o primeiro atribuiu mais biomassa aos rebentos do que o segundo. Embora N aumentou o crescimento de plantas invasivas, esse aumento não aumentou com o aumento da adição de N. Através das espécies invasivas e nativas, as mudanças na alocação da biomassa do extrato foram correlacionadas positivamente com as mudanças na biomassa da planta inteira; e a inclinação desse relacionamento foi maior em plantas invasivas do que plantas nativas. Essas descobertas sugerem que o aumento do investimento em lançamentos faz com que as plantas invasivas mantenham uma vantagem de crescimento em altas condições de N em relação aos nativos, e também destacar que a futura deposição de N pode aumentar os riscos de invasões de plantas.

Enhanced shoot investment makes invasive plants exhibit growth advantages in high nitrogen conditions.

Resource amendments commonly promote plant invasions, raising concerns over the potential consequences of nitrogen (N) deposition; however, it is unclear whether invaders will benefit from N deposition more than natives. Growth is among the most fundamental inherent traits of plants and thus good invaders may have superior growth advantages in response to resource amendments. We compared the growth and allocation between invasive and native plants in different N regimes including controls (ambient N concentrations). We found that invasive plants always grew much larger than native plants in varying N conditions, regardless of growth- or phylogeny-based analyses, and that the former allocated more biomass to shoots than the latter. Although N addition enhanced the growth of invasive plants, this enhancement did not increase with increasing N addition. Across invasive and native species, changes in shoot biomass allocation were positively correlated with changes in whole-plant biomass; and the slope of this relationship was greater in invasive plants than native plants. These findings suggest that enhanced shoot investment makes invasive plants retain a growth advantage in high N conditions relative to natives, and also highlight that future N deposition may increase the risks of plant invasions.

Enhanced shoot investment makes invasive plants exhibit growth advantages in high nitrogen conditions / O investimento de tiro aumentado faz plantas invasivas exposição de vantagens de crescimento em altas condições de nitrógeno

Resource amendments commonly promote plant invasions, raising concerns over the potential consequences of nitrogen (N) deposition; however, it is unclear whether invaders will benefit from N deposition more than natives. Growth is among the most fundamental inherent traits of plants and thus good invaders may have superior growth advantages in response to resource amendments. We compared the growth and allocation between invasive and native plants in different N regimes including controls (ambient N concentrations). We found that invasive plants always grew much larger than native plants in varying N conditions, regardless of growth- or phylogeny-based analyses, and that the former allocated more biomass to shoots than the latter. Although N addition enhanced the growth of invasive plants, this enhancement did not increase with increasing N addition. Across invasive and native species, changes in shoot biomass allocation were positively correlated with changes in whole-plant biomass; and the slope of this relationship was greater in invasive plants than native plants. These findings suggest that enhanced shoot investment makes invasive plants retain a growth advantage in high N conditions relative to natives, and also highlight that future N deposition may increase the risks of plant invasions.(AU)

As alterações de recursos geralmente promovem invasões de plantas, suscitando preocupações quanto às conseqüências potenciais da deposição de nitrogênio (N); No entanto, não está claro se os invasores se beneficiarão da deposição de N mais do que com os nativos. O crescimento é um dos traços inerentes mais fundamentais das plantas e, portanto, os bons invasores podem ter vantagens de crescimento superiores em resposta a alterações de recursos. Comparamos o crescimento e a alocação entre plantas invasivas e nativas em diferentes regimes de N, incluindo controles (concentrações ambientais de N). Descobrimos que as plantas invasivas sempre cresceram muito mais do que as plantas nativas em diferentes condições de N, independentemente das análises baseadas em crescimento ou filogenia, e que o primeiro atribuiu mais biomassa aos rebentos do que o segundo. Embora N aumentou o crescimento de plantas invasivas, esse aumento não aumentou com o aumento da adição de N. Através das espécies invasivas e nativas, as mudanças na alocação da biomassa do extrato foram correlacionadas positivamente com as mudanças na biomassa da planta inteira; e a inclinação desse relacionamento foi maior em plantas invasivas do que plantas nativas. Essas descobertas sugerem que o aumento do investimento em lançamentos faz com que as plantas invasivas mantenham uma vantagem de crescimento em altas condições de N em relação aos nativos, e também destacar que a futura deposição de N pode aumentar os riscos de invasões de plantas.(AU)

Identification of the CAD gene from Eucalyptus urophylla GLU4 and its functional analysis in transgenic tobacco.

Cinnamyl alcohol dehydrogenase (CAD) catalyzes the final step in lignin biosynthesis. The genus Eucalyptus belongs to the family Myrtaceae, which is the main cultivated species in China. Eucalyptus urophylla GLU4 (GLU4) is widely grown in Guangxi. It is preferred for pulping because of its excellent cellulose content and fiber length. Based on GLU4 and CAD gene expression, a Eucalyptus variety low in lignin content should be obtained using transgenic technology, which could reduce the cost of pulp and improve the pulping rate, and have favorable prospects for application. However, the role and function of CAD in GLU4 is still unclear. In the present study, EuCAD was cloned from GLU4 and identified using bioinformatic tools. Subsequently, in order to evaluate its impact on lignin synthesis, a full-length EuCAD RNAi vector was constructed, and transgenic tobacco was obtained via Agrobacterium-mediated transformation. A significant decrease in CAD expression and lignin content in transgenic tobacco demonstrated a key role for EuCAD in lignin biosynthesis and established a regulatory role for RNAi. In our study, the direct molecular basis of EuCAD expression was determined, and the potential regulatory effects of this RNAi vector on lignin biosynthesis in E. urophylla GLU4 were demonstrated. Our results provide a theoretical basis for the study of lignin biosynthesis in Eucalyptus.

Blockade of S100A3 activity inhibits murine hair growth.

Using mouse gene expression microarray analysis, we obtained dynamic expression profiles of the whole genome in a depilation-induced hair growth mouse model. S100A3 expression increased during the anagen phase and returned to normal during the telogen phase. The effects of S100A3 blockade on the hair growth cycle were examined in mice after subcutaneous injection of an anti-mouse S100A3 antibody. Protein localization of S100A3 was confined to the hair shafts during the anagen phase and the sebaceous glands during the telogen phase. S100A3 blockade delayed hair follicle entry into the anagen phase, decreased hair elongation, and reduced the number of hair follicles in the subcutis, which correlated with the downregulated expression of hair growth induction-related genes in vivo. The present study demonstrates that anti-S100A3 antibody inhibits mouse hair growth, suggesting that S100A3 can be used as a target for hair loss treatment.

Neuroprotective effect of ketamine on acute spinal cord injury in rats.

The aim of this study was to investigate the neuroprotective effects of ketamine during acute spinal cord injury in rats. Sprague Dawley (SD) rats (N = 70) were randomly divided into three groups: sham-operated (N = 10), control (N = 30), and treatment (N = 30) groups. The moderate spinal cord injury model was established. After injury, the sham-operated group received no drug, the treatment group received intraperitoneal ketamine injections, and the control group received intraperitoneal normal saline injections. Serum levels of tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and spinal cord malondialdehyde (MDA) were assessed, and nerve cell apoptosis was evaluated in each group at varying time points. After spinal cord injury, TNF-α, IL-6, and MDA levels, and the number of TUNEL-positive cells among 2500 cells significantly increased (P < 0.05). Further, compared with the control group, the treatment group showed significantly lower TNF-α, IL-6, and MDA levels, and fewer TUNEL-positive cells among 2500 cells at each time point (P < 0.05). Our data indicate that ketamine exerts a neuroprotective effect on injured spinal cord.

MicroRNA-21 promotes proliferation of rat hepatocyte BRL-3A by targeting FASLG.

Rat liver regeneration (RLR) induced by partial hepatectomy involves cell proliferation regulated by numerous factors, including microRNAs (miRNAs). miRNA high-throughput sequencing has been established and used to analyze miRNA expression profiles. This study showed that 39 miRNAs were related to RLR through the analysis of miRNA high-throughput sequencing. Their role toward rat normal hepatocyte line BRL-3A was studied by gain- and loss-of-function analyses, and one of them, microRNA-21 (miR-21), obviously upregulated and promoted BRL-3A cell proliferation. Using bioinformatics to search for miR-21 targets revealed that Fas ligand (FASLG) is one of miR-21's target genes. A dual-luciferase report assay and Western blot assay showed that miR-21 directly targeted the 3'-untranslated region of FASLG and inhibited the expression of FASLG, which suggests that miR-21 promoted BRL-3A cell proliferation by reducing FASLG expression.

Effects of angiotensin II intervention on MMP-2, MMP-9, TIMP-1, and collagen expression in rats with pulmonary hypertension.

This study investigated the effects of angiotensin II (AngII) intervention, using captopril and losartan, on the expression of matrix metalloproteinase-2 (MMP-2), MMP-9, tissue inhibitor of metalloproteinase-1 (TIMP-1), and collagen in rats with pulmonary hypertension, in an effort to understand mechanisms underlying pulmonary vascular remodeling. A total of 40 male Sprague-Dawley rats were randomly divided into normal group, model group, captopril group, and losartan group. After 5 weeks, the mean pulmonary arterial pressure (mPAP), right ventricular index, and neointima formation in each group were determined. Immunohistochemical analysis was performed to determine the degree of pulmonary arterial muscularization as well as MMP-2, MMP-9, and TIMP-1 protein expression in lung tissue. Real-time fluorescent quantitative PCR was used to detect MMP2, MMP9, TIMP1, COL1A1, and COL4A1 mRNA expression. Picro-sirius red staining was performed to detect collagen protein expression. Neointima formation was observed in the model group. Moreover, the mPAP, right ventricular index, degree of arterial muscularization, and collagen deposition, as well as mRNA and protein expression of MMP2, MMP9, and TIMP1 were significantly higher than those in the other groups (P < 0.05). The mPAP, right ventricular index, degree of arterial muscularization, and mRNA and protein expression in the captopril and losartan groups were significantly decreased compared with those of the model group (P < 0.05). AngII regulates MMP-2, MMP-9, and TIMP-1 expression and affects collagen deposition. Thus, this hormone is involved in pulmonary vascular remodeling, indicating a possible mechanism that can be targeted in pulmonary hypertension intervention.

Magnetic resonance spectroscopic imaging of brain injury after nasopharyngeal cancer radiation in early delayed reaction.

This study aimed to investigate the value of magnetic resonance spectroscopy (MRS) imaging in assessing nasopharyngeal carcinoma radiotherapy during the early delayed reaction period. Eighty cases of nasopharyngeal cancer treated with radiotherapy within the same period underwent MRS imaging before or after radiotherapy. Of the 80 cases, 47 underwent MRS imaging on the 3rd, 4th, 6th, and 12th months after radiotherapy. The trends of the primary metabolite concentration at different time points were monitored and compared with the corresponding data after radiotherapy. Repeated measures analysis of variance was performed. At the end of radiotherapy, the N-acetyl aspartate (NAA)/creatine (Cr), choline (Cho)/Cr, and NAA/Cho ratios were reduced to the lowest levels after 3 months. However, increasing trends were observed from the 4th to the 12th month. On the 12th month, stable levels were reached with statistically significant differences (F = 316.02, 53.84, 286.68; P < 0.01). MRS reflected the radiation injury-repair process in the brain of a nasopharyngeal cancer patient during early delayed reaction. This non-invasive monitoring of changes in brain tissue metabolite concentrations provides valuable information for prognosis.

Reduction of galectin-3 expression reduces pituitary tumor cell progression.

We investigated the role of galectin 3 in the development and progression of pituitary tumors. We used RNA interference to depress Gal-3 gene expression; MTT and flow cytometry were applied to detect changes in cell proliferation and apoptosis levels in pituitary tumor cells. Expression of apoptosis-associated genes, Bcl-2 and Baxk was analyzed by Western blot. Inhibition of Gal-3 gene expression by RNA interference decreased GH3 cell proliferation and increased cell apoptosis; the expression levels of Gal-3 protein significantly decreased, along with those of Bcl-2, although Bax levels did not change. We conclude that Gal-3 has an important role in pituitary tumor cell proliferation and progression; and it may be useful as a target for the treatment of aggressive pituitary tumors.

RNA interference of leptin receptor in chicken adipocytes.

In this study, chicken adipocytes were cultured to evaluate RNA interference by the leptin receptor gene. A small interfering RNA of the leptin receptor gene was synthesized, with a suppression rate of 60% being generated (P < 0.01). After the knockdown of the leptin receptor, the expression levels of certain genes decreased significantly; specifically, peroxisome proliferator-activated receptor γ, fatty acid synthase, adipose triglyceride lipase, and lipoprotein lipase. In addition, a significant increase in the expression of the adiponectin gene was documented. These results demonstrate that the leptin receptor gene might contribute to lipid metabolism by influencing the expressions of the peroxisome proliferator-activated receptor γ, fatty acid synthase, adipose triglyceride lipase, lipoprotein lipase, and adiponectin genes.

Molecular cloning, expression, and regulation of estrogen receptors in pigeon oviduct epithelial cells.

Estrogen regulates reproductive behavior and drives the proliferation and differentiation of several cell types. These physiological functions of estrogen are mediated by estrogen receptors (ERs), and each ER isoform plays a distinct role. To clarify the molecular mechanism of estrogen action and to evaluate the effect of ERs on the secretion of ovalbumin (OVA) in pigeon oviduct epithelial cells (POECs), we determined the complete coding sequences encoding ER alpha (ERα) and ER beta (ERß) in pigeons. The abundance of pigeon ERα and ERß mRNA was detected using quantitative polymerase chain reaction. These results revealed that pigeon ERα is highly expressed in the oviduct, while pigeon ERb is highly expressed in the ovary and kidney. We hypothesize that ERα mRNA predominates over that of ERß in the oviduct. The expression of ERα can be down-regulated by 17ß-estradiol, and the knockdown of ERα promoted OVA mRNA expression in cultured POECs, indicating that ERα may play an important role in OVA secretion.

Construction and analysis of a subtractive cDNA library of early embryonic development in duck.

Several studies have documented the process of early embryonic development in poultry; however, the molecular mechanisms underlying its developmental regulation are poorly understood, particularly in ducks. In this study, we analyzed differential gene expression of embryos 6 and 25 h following oviposition to determine which genes regulate the early developmental stage in ducks. Among 216 randomly selected clones, 39 protein-encoding cDNAs that function in metabolism, transcription, transportation, proliferation/apoptosis, cell cycle, cell adhesion, and methylation were identified. Additionally, the full-length cDNA of the Nanog gene, encoding a 302-amino acid protein, was obtained. Quantitative real-time polymerase chain reaction analyses were performed to detect expression levels of the selected genes during early and late embryonic stages, which revealed that these genes are expressed in a particular spatial and temporal pattern. These results indicate that these genes may play pivotal roles in the process of area pellucida formation through a complex and precise regulatory network during development in duck embryos.

Sexual reproduction development in apomictic Eulaliopsis binata (Poaceae).

Apomixis is a particular mode of reproduction that allows progeny formation without meiosis and fertilization. Eulaliopsis binata, a tetraploid apomictic species, is widely used for making paper, rope and mats. There is great potential for fixation of heterosis in E. binata due to autonomous endosperm formation in this species. Although most of its embryo sac originates from nucellus cells, termed apospory, we observed sexual reproduction initiation in 86.8 to 96.8% of the ovules, evidenced by callose deposition on the walls of cells undergoing megasporogenesis. However, only 2-3% mature polygonum-type sexual embryo sacs were confirmed by embryological investigation. Callose was not detected on aposporous initial cell walls. The aposporous initial cells differentiated during pre- and post-meiosis of the megaspore mother cell, while the sexual embryo sac degenerated at the megaspore stage. DNA content ratio of embryo and endosperm in some individuals was 2C:3C, based on flow cytometry screening of seed, similar to that of normal sexual seed. These results confirm that apomictic E. binata has conserved sexual reproduction to a certain degree, which may contribute to maintaining genetic diversity. The finding of sexual reproduction in apomictic E. binata could be useful for research on genetic mechanism of apomixis in E. binata.

Effect of hyperoxia on the intestinal IgA secretory component in neonatal rats and on intestinal epithelial cells in vitro

Oxygen therapy is essential for the treatment of some neonatal critical care conditions but its extrapulmonary effects have not been adequately investigated. We therefore studied the effects of various oxygen concentrations on intestinal epithelial cell function. In order to assess the effects of hyperoxia on the intestinal immunological barrier, we studied two physiological changes in neonatal rats exposed to hyperoxia: the change in intestinal IgA secretory component (SC, an important component of SIgA) and changes in intestinal epithelial cells. Immunohistochemistry and Western blot were used to detect changes in the intestinal tissue SC of neonatal rats. To detect intestinal epithelial cell growth, cells were counted, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Giemsa staining were used to assess cell survival. Immunohistochemistry was used to determine SC expression. The expression of intestinal SC in neonatal rats under hyperoxic conditions was notably increased compared with rats inhaling room air (P < 0.01). In vitro, 40 percent O2 was beneficial for cell growth. However, 60 percent O2 and 90 percent O2 induced rapid cell death. Also, 40 percent O2 induced expression of SC by intestinal epithelial cells, whereas 60 percent O2did not; however, 90 percent O2 limited the ability of intestinal epithelial cells to express SC. In vivo and in vitro, moderate hyperoxia brought about increases in intestinal SC. This would be expected to bring about an increase in intestinal SIgA. High levels of SC and SIgA would serve to benefit hyperoxia-exposed individuals by helping to maintain optimal conditions in the intestinal tract.

Effect of hyperoxia on the intestinal IgA secretory component in neonatal rats and on intestinal epithelial cells in vitro.

Oxygen therapy is essential for the treatment of some neonatal critical care conditions but its extrapulmonary effects have not been adequately investigated. We therefore studied the effects of various oxygen concentrations on intestinal epithelial cell function. In order to assess the effects of hyperoxia on the intestinal immunological barrier, we studied two physiological changes in neonatal rats exposed to hyperoxia: the change in intestinal IgA secretory component (SC, an important component of SIgA) and changes in intestinal epithelial cells. Immunohistochemistry and Western blot were used to detect changes in the intestinal tissue SC of neonatal rats. To detect intestinal epithelial cell growth, cells were counted, and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and Giemsa staining were used to assess cell survival. Immunohistochemistry was used to determine SC expression. The expression of intestinal SC in neonatal rats under hyperoxic conditions was notably increased compared with rats inhaling room air (P < 0.01). In vitro, 40% O2 was beneficial for cell growth. However, 60% O2 and 90% O2 induced rapid cell death. Also, 40% O2 induced expression of SC by intestinal epithelial cells, whereas 60% O2 did not; however, 90% O2 limited the ability of intestinal epithelial cells to express SC. In vivo and in vitro, moderate hyperoxia brought about increases in intestinal SC. This would be expected to bring about an increase in intestinal SIgA. High levels of SC and SIgA would serve to benefit hyperoxia-exposed individuals by helping to maintain optimal conditions in the intestinal tract.