mTORC1 signaling pathway regulates tooth repair

Tooth germ injury can lead to abnormal tooth development and even tooth loss,affecting various aspects of the stomatognathic system including form,function,and appearance.However,the research about tooth germ injury model on cellular and molecule mechanism of tooth germ repair is still very limited.Therefore,it is of great importance for the prevention and treatment of tooth germ injury to study the important mechanism of tooth germ repair by a tooth germ injury model.Here,we constructed a Tg(dlx2b:Dendra2-NTR)transgenic line that labeled tooth germ specifically.Taking advantage of the NTR/Mtz system,the dlx2b+tooth germ cells were depleted by Mtz effectively.The process of tooth germ repair was evaluated by antibody staining,in situ hybridization,Ed U staining and alizarin red staining.The severely injured tooth germ was repaired in several days after Mtz treatment was stopped.In the early stage of tooth germ repair,the expression of phosphorylated 4E-BP1 was increased,indicating that mTORC1 is activated.Inhibition of mTORC1 signaling in vitro or knockdown of mTORC1 signaling in vivo could inhibit the repair of injured tooth germ.Normally,mouse incisors were repaired after damage,but inhibition/promotion of mTORC1 signaling inhibited/promoted this repair progress.Overall,we are the first to construct a stable and repeatable repair model of severe tooth germ injury,and our results reveal that mTORC1 signaling plays a crucial role during tooth germ repair,providing a potential target for clinical treatment of tooth germ injury.

Effect of reduced energy density of close-up diets on dry matter intake,lactation performance and energy balance in multiparous Holstein cows

Energy intake prepartum is critically important to health, milk performance, and profitability of dairy cows. The objective of this study was to determine the effect of reduced energy density of dose-up diets on dry matter intake （DMI）, lactation performance and energy balance （EB） in multiparous Holstein cows which were housed in a free-stall barn and fed for ad libitum intake. Thirty-nine dry cows were blocked and assigned randomly to three groups fed a high energy density diet [HD, n = 13; 6.8 MJ of net energy for lactation （NEL）/kg; 14.0% crude protein （CP） ], or a middle energy density diet （MD, n = 13; 6.2 MJ NEh/kg; 14.0% CP）, or a low energy density diet （LD, n = 13; 5.4 MJ NEh/kg; 14.0% CP） from d 21 before expected day of calving. After parturition, all cows were fed the same lactation diet to d 70 in milk （DIM）. The DMI and NEE intake prepartum were decreased by the reduced energy density diets （P 〈 0.05）. The LD group consumed 1.3 last 24 h before calving. The milk yield and the postpartum kg/d （DM） more diet compared with HD group in the DMI were increased by the reduced energy density diet prepartum （P 〈 0.05）. The changes in BCS and BW prepartum and postpartum were not affected by prepartum diets HD group had higher milk fat content and lower lactose content compared with LD group during the first 3 wk of lactation （P 〈 0.05）. The energy consumption for HD, MD and LD groups were 149.8%, 126.2% and 101.1 % of their calculated energy requirements prepartum （P 〈 0.05）, and 72.7%, 73.1% and 7.5.2% during the first 4 wk postpartum, respectively. In conclusion, the low energy density prepartum diet was effective in controlling NF_L intake prepartum, and was beneficial in increasing DMI and milk yield, and alleviating negative EB postpartum.

Reducing Carbon Emissions Resulting from Livestock Production Using Ruminants: A Review

Greenhouse gas emissions are increas- ing every year and their effect on the environment is becoming increasingly serious. In 2009, the concen- tration of carbon dioxide in the earth＇s atmosphere reached 387 μL/L, the highest level in recorded histo- ry. This paper summarizes the global carbon emission situation, sources of greenhouse gases, and the con-tribution of agriculture to the accumutauon ot green- house gases. Several scientific measures are proposed to reduce greenhouse gas emissions resulting from ru- minant production such as improving animal perform- ance, regulating the rumen environment, and reduc- ing the amount of greenhouse gases emitted from live- stock manure.

Light-induced protein translocation by genetically encoded unnatural amino acid in Caenorhabditis elegans

Dear Editor,Living systems such as Caenorhabditis elegans are organized by interaction networks of biopolymer and small mol-ecules.The molecular engineering of specifi c targets to monitor and control these biological molecules has led to significant advances in our understand-ing of how biological systems are organ-ized,maintain themselves and disin-tegrate(Prescher and Bertozzi,2005).For instance,green fl uorescent protein(GFP)derived from jellyfi sh Aequorea Victoria helps us to accurately locate and observe proteins over long term periods.In addition,many novel LOV(light,oxy-gen,or voltage)domains such as LOV2-Jαand Vivid offer the possibility of cell-based motility management and tissue-based gene expression control(Wu et al.,2009;Wang et al.,2012).