Presynaptic quantal size enhancement counteracts post-tetanic release depression.

Repetitive synaptic stimulation can induce different forms of synaptic plasticity but may also limit the robustness of synaptic transmission by exhausting key resources. Little is known about how synaptic transmission is stabilized after high-frequency stimulation. In the present study, we observed that tetanic stimulation of the Drosophila neuromuscular junction (NMJ) decreases quantal content, release-ready vesicle pool size and synaptic vesicle density for minutes after stimulation.

Assessment of the effects of heat stress on the production of dairy cows by using two comfort thermal indices in Southern Chile.

Heat stress has been recognized as a serious problem in dairy farms around the world due to the increasing heat waves and higher genetic potential of dairy cows. In Chile, milk production is concentrated in the southern regions of the country, where animals graze all year around, consequently being exposed directly to environmental conditions. Nevertheless, there are few studies conducted in Chile that have evaluated at the commercial level the impact of heat stress on milk production.

A retrospective analysis of sheep generated by somatic cell nuclear transfer.

Somatic cell nuclear transfer (SCNT) is one of the primary methods for production of genetically engineered sheep, which allows for gene editing or transgene introduction in somatic cells. The use of SCNT eliminates the risk of genetic mosaicism in embryos and animals that is commonly observed after zygote micromanipulations. This retrospective analysis of SCNT in sheep performed at Utah State University, spanning from 2016 to 2021, examined parameters that may impact pregnancy and full-term development, including donor oocytes (donor age), donor cell lines, SCNT parameters (time of oocyte activation following SCNT, number of transferred embryos, in vitro maturation and culture conditions), and recipients (surgical number and ovulatory status), as well as factors that may correlate with large offspring syndrome or abnormal offspring syndrome (LOS/AOS) in the fetuses and lambs.

Estimation of the economic impact of heat stress on the Chilean dairy regions by using two comfort thermal indices.

The study aimed to estimate economic losses associated with heat stress in the eight dairy production regions (DPR), defined by the Dairy Chilean Consortium, using two comfort thermal indices, namely, the temperature-humidity index (THI) and the THI adjusted for solar radiation and wind speed (THIa). Hourly records from 19 weather stations (Nov - Mar 2017-2022) were collected to estimate the comfort thermal indices. The economic impact was estimated considering a critical threshold of 65 for both indices and the effect of higher values on loss in milk yield, days open, culling rate, and deaths.