[Levels of human milk oligosaccharides in breast milk of mothers delivering preterm infants of different gestational ages and their effects on early growth and development].

Objective: To investigate the human milk oligosaccharides (HMOs) levels in breast milk of mothers delivering preterm infants and their effects on the early growth and development of infants. Methods: In this prospective cohort study, full-term and preterm newborns whose parents decided to breastfeed were recruited from Peking University Third Hospital between December 1, 2017 and November 30, 2018. The preterm infants were divided based on their gestational ages into extremely preterm (<28 weeks), very preterm (28-31+6 weeks) and moderate to late preterm (32-36+6 weeks) groups. Breast milk was collected from mothers at 7, 14, 28 and 120d postpartum. 368 breast milk samples were collected from 125 mothers in this study, including 54 mothers of full-term infants, 23 mothers of moderate to late preterm infants, 39 mothers of very preterm infants, and 9 mothers of extremely preterm infants. Ultra-performance liquid chromatography-mass spectrometer (UPLC-MS/MS) was used to determine the concentration of 2'-fucosyllactose (2'FL), 3-fucosyllactose (3FL), 3'-sialyllactose (3'SL), A-tetrasaccharide (P1), lacto-N-tetraose (LNT), lacto-N-neotetraose (LNnT), lacto-N-fucopentaose Ⅱ (LNFP-Ⅱ) and lacto-N-fucopentaose Ⅴ (LNFP-Ⅴ). Secretor status of mothers was defined as 2'-fucosyllactose (2'FL) concentration in colostrum and transitional milk greater than 200 µg/mL. Weight gain and the occurrence of allergic diseases of infants were collected at 120 d(4 months) postpartum. The chi-square test or the Fisher's exact test was used for the comparison of categorical data between groups; Kruskal-Wallis test and Wilcoxon rank sum test were used for comparison of continuous data between groups. Nemenyi test was used for multiple comparison. Results: 79.2% (99/125) of the mothers were secretor. There were no statistical differences between groups in the secretor status of mothers (χ²=1.31,P>0.05). The total concentration of HMOs peaked at 1-2 weeks postpartum. Compared to the preterm milk, the HMOs from the term milk was trending downwards at an earlier time. In the breast milk of secretor mothers on 28 d, total concentration of HMOs significant differed among the three groups of preterm milk and the term milk, with the median value of 4 587.09,4 615.25,5 277.44,5 476.03 µg/mL, respectively (Kruskal-Wallis χ²=8.1234,P=0.044). When analyzed by the median weight gain of the infants (low vs high weight gain) at 4 months postpartum, 2'FL was significantly lower in the high weight gain group at 7 d (1 818.04 µg/mL vs 2 181.67 µg/mL, W=1 386,P=0.018), while LNT & LNnT were significantly higher (1 182.36 µg/mL vs 1 053.62 µg/mL, W=816,P=0.044). The level of 3FL at 120 d was significantly affected by presence of allergic disease in infants, breast milk from mothers of infants with allergic disease had lower 3FL than those from mothers of infants without allergic disease (256.17 µg/mL vs 286.18 µg/mL, W=564,P=0.026). Conclusions: The overall profiles of HMOs in breast milk of mothers delivering preterm infants was basically the same as that of mothers delivering term infants; individual HMOs play a role in weight gain and the development of allergic diseases in preterm infants, but the mechanism is unclear and needs further study.

Isolation and characterization of polymorphic EST-SSR and genomic SSR markers in spotted mandarin fish (Siniperca scherzeri Steindachne).

Spotted mandarin fish (Siniperca scherzeri Steindachne) feed solely on live fry of other fish species once the fry start feeding in the wild. In the present study, 26 polymorphic transcriptome-derived simple sequence repeat (SSR) markers and 14 genomic SSR markers were developed and characterized in S. scherzeri Steindachne by combining a biotin-enrichment protocol and transcriptome of F1 interspecies hybrids between S. chuatsi (♀) and S. scherzeri (♂). These 40 polymorphic SSRs amplified 168 alleles (mean 4.2). The number of alleles, observed heterozygosity, expected heterozygosity, and polymorphic information content per locus were in the range of 2 to 7 (mean 4.3), 0.1111 to 1.000 (mean 0.6718), 0.3118 to 0.8276 (mean 0.6901), and 0.2735 to 0.7902 (mean 0.6298), respectively. Ten of these microsatellite loci deviated significantly from Hardy-Weinberg equilibrium (P < 0.00125) after Bonferroni correction for multiple tests and no significant linkage disequilibrium (P < 0.00006) was observed. The microsatellite markers characterized from S. scherzeri could be a valuable tool in genetic evaluation for conservation and for assessment of the mechanism associated with unique food preference of S. scherzeri from a genetic point of view.

Characterization of microsatellite markers and their correlations with growth traits in Mandarin fish (Siniperca chuatsi).

Mandarin fish (Siniperca chuatsi) is a traditionally cultured freshwater fish with high commercial value in China. To facilitate marker-assisted selection for genetic improvement of this species, 100 microsatellite markers identified in previous studies were characterized in the 25 largest and 25 smallest individuals. Twenty polymorphic loci were used to genotype 200 individuals, and the associations between their genotypes and growth traits were examined. We found that 9 genotypes at 8 loci (SC-10, Sin 135, Sin 166, AP 34-23, AP 38-11, AP 37-22, AP 37-08, and AP 37-37) were positively correlated with growth traits (body weight, body length, body height) in the mandarin fish population. The average of observed and expected heterozygosities were 0.71 and 0.59, respectively, and the average polymorphism information content value was 0.54, indicating that the population had high genetic diversity. The markers developed in this study are useful for selection of genetic breeding in this species and its related species.

Microsatellite DNA markers and their correlation with growth traits in mandarin fish (Siniperca chuatsi).

The mandarin fish (Siniperca chuatsi) is a traditionally cultured freshwater fish with high commercial value in China. To facilitate marker-assisted selection in genetic improvement of this species, 120 microsatellite markers from the literature were characterized in the 25 largest and 25 smallest individuals. Eighteen polymorphic loci were then used to genotype 200 individuals, and the associations between their genotypes and growth traits were examined. We found that eight genotypes of six loci (AP 37-06, AP 37-11, AP 37-16, AP 37-48, AP 38-32, and AP 39-05) were positively correlated with growth traits (body weight, length, and height) in the mandarin fish population. The average observed and expected heterozygosities were 0.68 and 0.59, respectively, and the average PIC value was 0.50, indicating a population with high genetic diversity. Therefore, these markers could be useful for assisted selection in genetic breeding of this species and its related species.

New microsatellite loci for the mandarin fish Siniperca chuatsi and their application in population genetic analysis.

The mandarin fish is a popular fresh water food fish in China. Fifty-three polymorphic microsatellite markers were isolated through construction of an enriched library of genomic DNA of Siniperca chuatsi (Percichthyidae). We found 2 to 7 alleles per locus. The observed and expected heterozygosity values varied from 0.059 to 1.000 and from 0.305 to 0.818, respectively. The polymorphic information content value varied from 0.255 to 0.782. Twelve microsatellite loci deviated significantly from Hardy-Weinberg equilibrium after Bonferroni's correction. These markers were evaluated in five species of sinipercine fish; 98% of the 265 locus/taxon combinations tested gave cross-amplification. Eight polymorphic microsatellite markers were randomly selected for genetic characterization of three S. chuatsi populations. The Ganjiang River and Yuanjiang River populations had moderate levels of genetic diversity, while the Mudanjiang River population had a relatively low level genetic diversity. Genetic distance-based cluster analysis showed clustering of the Ganjiang River and Yuanjiang River populations in a single group and the Mudanjiang River population in a separate group. Based on these results, we suggest that S. chuatsi from the Yangtze River watershed are distinct from the Mudanjiang River population. These SSR markers will be useful for diversity, mapping and marker assisted studies of S. chuatsi and other sinipercine fishes.

Development and characterization of novel SSR markers in Siniperca kneri Garman.

In this study, 37 transcriptome-derived simple sequence repeat (SSR) markers and 18 genomic SSR markers were developed and characterized in the Chinese perch, Siniperca kneri Garman. The average allele number per locus was 5.1 (range: 2-8) for transcriptome-derived SSRs and 3.8 (range: 2-5) for genomic SSRs. The average observed and expected heterozygosities were 0.666 (range: 0.000-1.000) and 0.692 (range: 0.230-0.857) for transcriptome-derived SSRs, respectively. These values were 0.380 (range: 0.000-1.000) and 0.527 (range: 0.201-0.799) for genomic SSRs, respectively. The average polymorphic information content was 0.638 (range: 0.215-0.824) for transcriptome-derived SSRs and 0.477 (range: 0.183-0.752) for genomic SSRs. Seven of these loci exhibited departure from Hardy-Weinberg equilibrium after sequential Bonferroni's correction for multiple tests, and no significant deviation was observed for the linkage disequilibrium. These developed and characterized markers are anticipated to be useful for studies on population genetics, conservation genetics, and the fishery management of this species.