| This paper selected male Hu lamb at different ages from month 0 to 6 to explore themechanism and characteristics of the mRNAs expression of the genes related tointramuscular fat (IMF) content, so as to help the breeding of sheep. The researches heremainly focused on these aspects: the IMF content of different parts of muscles (longissimusdorsi muscle, psoas major muscle, biceps femoris muscle) were detected by using Soxhletpetroleum-ether extraction; mRNAs expression levels were analysed by the relativequantitative method real time PCR with GAPDH mRNA as the internal standard; Therelativities between mRNAs expression levels of different genes and those betweenmRNAs expression levels and IMF content were explored. The results were as follows:1. The developmental changes of IMF content in different parts of Hu lamb muscles1) The IMF contents showed increased with growth in different parts of Hu lambmuscle in 0-6 month ages, the IMF contents in month 5～6 were significantly higher thanprevious in all the muscles (P＜0.01); the IMF content in month 2 was obviously higher thanday 0 in longissimus dorsi muscle (P＜0.05); in psoas major muscle the IMF content inmonth 3 was obviously higher than day 0 (P＜0.05); from birth to month 6, the contents ofIMF in longissimus dorsi muscle were higher than psoas major muscle and biceps femorismuscle; it suggested that the different characters of accumulation of IMF in different partsof muscles; 2) the term of 4～5 month was the most important time for IMF accumulation inHu lamb. 2. The developmental changes of muscle OB mRNAs expression levels and theireffects on IMF contents in different parts of Hu lamb muscles1) The longissimus dorsi muscle OB mRNAs expression level was the highest inmonth 3 (P＜0.01); inpsoas major muscle the gene expression level was the highest on birth,obviously higher than month 2～3 (P＜0.05), then it reached the lowest level on month 3 andincreased after month 4; the biceps brachii muscle OB mRNAs expression level was thehighest on birth, it showed obviously higher than month 3, 5 and 6, then decreased afterthat and reached the lowest level on month 6; in biceps femoris muscle the gene expressionwas different from other parts of muscle, it was lower on birth and got highest level onmonth 3 (P＜0.01), after month 3 the mRNAs of OB kept a lower level; 2) OB mRNAslevels in psoas major and biceps brachii muscle were significantly higher than inlongissimus dorsi and biceps femoris muscle (P＜0.01) on birth; on month 3, the geneexpression in longissimus dorsi were significantly higher than psoas major and bicepsbrachii muscle (P＜0.01), biceps femoris muscle were higher than psoas major and bicepsbrachii muscle (P＜0.05), it suggested that the characteristics of OB gene expression insheep muscle were tissues-dependent; 3) The mRNAs level of OB were negativelycorrelated with that of IMF contents in longissimus dorsi muscle (r=-0.405, P=0.119) andin biceps femoris muscle (r=-0.303, P=0.194) from month 3 to 6, it gave us an indicationthat OB expression in sheep muscles may have negative effects on IMF growth.3. The developmental changes of muscle OBR mRNAs expression levels and theireffects on IMF contents in different parts of Hu lamb muscles1) The OBR mRNAs expression had a similar pattern in different parts of Hu lambmuscle, the gene expression levels were lower on birth and then increased with growth,then had the highest level on month 3; in psoas major muscle the OBR mRNAs levels onmonth 2 were significantly higher than that of 0～1 month and 4～6 month old (P＜0.01); inlongissimus dorsi muscle the gene expression levels on aged 3 month showed obviouslyhigher than aged 2 and 6 month (P＜0.05); the OBR mRNAs levels on month 3 weresignificantly higher than that of other age groups in biceps brachii muscle (P＜0.01); in biceps femoris muscle the gene levels on month 3 were significantly higher than that termsof 0～1 and 5～6 month (P＜0.01), obviously higher than aged 4 month (P＜0.05); 2) TheOBR mRNAs levels in different parts of muscle on the same age showed that, on month 2biceps femoris muscle showed significantly higher than longissimus dorsi muscle (P＜0.01),on month 3 biceps brachii muscle and biceps femoris muscle were higher than psoas majorand longissimus dorsi muscle (P＜0.05), on month 3 biceps femoris muscle showedsignificantly higher than psoas major muscle (P＜0.01), it revealed that the developmentalchanges of OBR expression in sheep muscle were tissues-and ages-dependent; 3) In bicepsfemoris muscle the OBR mRNAs levels showed obviously negatively correlated with thatof IMF contents (r=-0.433, P=0.012), in longissimus dorsi (r=-0.128, P=0.209) andpsoas major muscle (r=-0.254, P=0.168) we found similar relationship, it suggested thatthe OBR mRNAs levels may have negative effects on IMF accumulation.4. The developmental changes of hypothalamus OBR mRNAs expression levels in Hulamb1) The hypothalamus OBR mRNAs expression levels were steadily from birth to 6month old; 2) There were no obvious relationships were found between the OBR mRNAs inhypothalamus and IMF contents in all parts of Hu lamb muscles.5. The developmental changes of mRNAs expression levels of muscle FAS genes andtheir effects on IMF in Hu lamb1) With growing, FAS mRNAs expression levels in longissimus dorsal muscleincreased and reached highest level on 5 month old (P＜0.01); in psoas major muscle thesituation were opposite, the gene was the highest on month 2 and the lowest on month 4,the gene level on month 2 were significantly higher than that of aged from 4 to 4 month(P＜0.01), on month 4 were significantly lower than that of aged 0～2 month (P＜0.01); withgrowth, FAS mRNAs level increased firstly, then declined in biceps brachii muscle, withthe expression peak appearing at month 3, which were significantly higher than other agegroups (P＜0.01); in biceps femoris muscle FAS mRNAs levels were lower on birth and showed a peak on month 3, then decreased quickly on month 4, which significantly lowerthan that of month 3 and 6 (P＜0.01); 2) excepting for month 4 old, psoas major muscle FASmRNAs levels were obviously higher than that other parts of muscle (P＜0.01), on month 2and 5～6 old, longissimus dorsal muscle FAS mRNAs levels were obviously higher than thatother parts of muscle (P＜0.01), on month 3 old, biceps brachii muscle FAS mRNAs levelswere obviously higher than that other parts of muscle (P＜0.01); 3) The relationshipsbetween FAS mRNAs and IMF contents showed that obviously positive in longissimusdorsal muscle from 0 to 6 month old (r=0.606, P=0.005), psoas major muscle (r=0.360P=0.187) and biceps femoris muscle (r=0.471, P=0.076) from 4 to 6 month old, itsuggested that the FAS gene expression may have positive effects on IMF contents in sheep.6. The developmental changes of mRNAs expression levels of muscle HSL genes andtheir effects on IMF in Hu lamb1) The HSL gene expression level were the lowest on birth in longissimus dorsalmuscle, and increased with growth, reached the highest peak at 6 month old (P＜0.01); inpsoas major muscle it showed "decreased-increased-decreased- increased" patterns and thehighest one appeared at month 3, which significantly higher than that of aged 1 and 4month (P＜0.01), in biceps brachii muscle the gene revealed decreased firstly, then climbedand lastly declined again, on month 2 it was the lowest and which obviously lower than thatof on birth (P＜0.01); in biceps femoris muscle the highest gene expression of HSL appearedat month 3, and on month 4 it was the lowest level quickly, the difference between month 3and 4 was significantly (P＜0.01); 2) From on birth to month 6, psoas major muscle HSLmRNAs levels were significantly higher than that of other parts of muscles (P＜0.01),longissimus dorsal muscle and biceps femoris muscle HSL levels were the lowest (P＜0.01)apparently on birth and on month 4, on month 6; 3) The relationships between in HSLmRNAs expression and IMF contents were positively in all parts of Hu lamb muscle, longissimus dorsal muscle(r=0.630, P=0.0003), psoas major (r=0.589, P=0.02)andbiceps femoris muscle (r=0.280, P=0.121) from month 4 to 6.7. The developmental changes of mRNAs expression levels of muscle LPL genes andtheir effects on IMF in Hu lamb1) The developmental changes of LPL gene expression in different parts of Hu lambmuscle were different: in longissimus dorsal muscle it was increased with growing, andshowed the highest on month 5, which higher than that of month 1～4 (P＜0.05) andobviously higher than that of on birth (P＜0.01); inpsoas major muscle the gene expressionlevel were steadily before month 3, and appeared lowest on month 4, after that period, thegene expression level increased back; in biceps brachii muscle, on month 3 and 5 the LPLmRNAs showed highest levels, which significantly higher than that of other groups(P＜0.01); in biceps femoris muscle there were no obviously differences between differentages; 2) on birth, biceps femoris muscle LPL mRNAs were the highest in all the muscles(P＜0.01), on month 6 biceps brachii muscle LPL gene expression were the lowest in all themuscles (P＜0.01); 3) In longissimus dorsal muscle the LPL mRNA expression werepositively correlated to the IMF content (r=0.503, P=0.005) from on birth to month 6, inbiceps femoris muscle the relationship were positive too (r=0.294, P=0.102), it revealedthat the LPL gene expression in sheep muscle may have positive effects on IMFaccumulation.8. The developmental changes of mRNAs expression levels of muscle UCP3 genes andtheir effects on IMF in Hu lamb1) The developmental changes of UCP3 mRNAs expression levels in Hu lamb musclewere showed that: in longissimus dorsal muscle it was the highest on month 1 and thendeclined with growth; in psoas major muscle it showed climbed firstly and declined lastly,and had a peak on month 3; in biceps brachii muscle the gene expression were the higheston month 2 and the lowest on month 3; in biceps femoris muscle the gene kept a steadily level from birth to month 6, there were no obviously differences between age groups in allparts of Hu lamb muscles; 2) on month 3 thc psoas major muscle had the highest level ofUCP3 gene expression (P＜0.05) in all the muscles; 3) In Iongissimus dorsal muscle theUCP3 gene expression and IMF had a negative relationship (r=-0.211, P=0.262) frombirth to month 6, in biceps femoris muscle the gene expression and IMF showed negativerelationship too (r=-0.209, P=0.328) from month 2～6, in psoas major muscle therelationship were the same as other muscles (r=-0.286, P=0.266) on the term of 3～6month old, it suggested that UCP3 gene expression in sheep muscle may have a negativeeffects on IMF growth.
|
PDF Full Text Request