Ovulation response to pregnant mares' serum gonadotrophin in prepubertal ewe lambs of different Booroola genotypes

Ovulation rates following treatment with PMSG were measured in prepubertal ewe lambs of known Booroola genotype to evaluate the technique as a method of early identification of Booroola genotypes. Two experiments were conducted with homozygous (FF), heterozygous (F+) and non-carrier (++) interbred $\text{1}\text{2}$ Merino $\text{1}\text{2}$ Romney breed type ewe lambs and a third experiment compared first cross F+ $\text{1}\text{2}$ Merino $\text{1}\text{2}$ Coopworth breed type with contemporary Coopworths (++). The ewe lambs aged 5–6 months were injected with 400 or 600 i.u. PMSG. The percentage of ewe lambs ovulating following treatment with PMSG was similar in all experiments (75–77%) but in Experiment 1 the FF and F+ lambs had a significantly higher proportion ovulating than the ++ lambs (P<0.05). The mean ovulation rate of FF ewe lambs treated with PMSG was 1.03 (Expt 1) and 1.69 (Expt 2) higher than ++ lambs (P<0.05). In Experiment 1 the mean ovulation rate of F+ ewe lambs was 0.33 higher than ++ ewe lambs but this difference was not significant. However, in Experiments 2 and 3 the mean ovulation rate of F+ ewe lambs treated with 600 i.u. PMSG was 1.06 and 0.45 higher than ++ ewe lambs respectively (P< 0.05). These results show that PMSG treatment is a promising technique for identifying the Booroola genotype of ewe lambs at an early age but further experiments with different dose rates of PMSG and different ages and liveweights of lambs are required to determine optimum dose rates and time of treatment.     

Changes in topoisomerase I activity after irradiation of lymphoid cells

The activity of topoisomerase I in nuclear extracts increased about three-fold 5 min after gamma-irradiation (840-2500 rads) of human peripheral blood lymphocytes or cultured lymphoblastoid cells. The change may reflect modification of the enzyme by nuclear ADP-ribosyl transferase, which is known to be activated by DNA breaks.     

Modulation of Synaptic Vesicle Exocytosis in Muscle-Dependent Long-Term Depression at the Amphibian Neuromuscular Junction

We have labeled recycling synaptic vesicles at the somatic Bufo marinus neuromuscular junction with the styryl dye FM2-10 and provide direct evidence for refractoriness of exocytosis associated with a muscle activity-dependent form of long-term depression (LTD) at this synapse. FM2-10 dye unloading experiments demonstrated that the rate of vesicle exocytosis from the release ready pool (RRP) of vesicles was more than halved in the LTD (induced by 20 min of low frequency stimulation). Recovery from LTD, observed as a partial recovery of nerve-evoked muscle twitch amplitude, was accompanied by partial recovery of the refractoriness of RRP exocytosis. Unexpectedly, paired pulse plasticity, another routinely used indicator of presynaptic forms of synaptic plasticity, was unchanged in the LTD. We conclude that the LTD induces refractoriness of the neuromuscular vesicle release machinery downstream of presynaptic calcium entry.     

Novel racemosin B derivatives as new therapeutic agents for aggressive breast cancer

Carbazole derivatives show anti-cancer activity and are of great interest for drug development. In this study, we synthesized and analyzed several new alkylamide derivatives of racemocin B, a natural indolo[3,2-a]carbazole molecule originally isolated from the green alga Caulerpa racemose. Several alkylamide derivatives were found to exhibit moderate to strong growth inhibition against human breast cancer cell lines. They induced G2/M cell cycle arrest and apoptosis in the aggressive triple-negative breast cancer cell line MDA-MB-231. Among these derivatives, compound 25 with the lowest IC₅₀ induced cell death by suppressing autophagy. This was accompanied by inhibition of autophagic flux and accumulation of autophagy protein 1 light chain 3, LC3II, and p62. The novel alkylamide derivative offers a potential new treatment for human breast cancer.