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Scientists were able to isolate children suffering from the result of cocaine, specifically, by testing for the presence of non-medically administered drugs of abuse and for alcohol in blood samples taken from the umbilical cord. Patients positive from any other drug use were excluded from the study. This allowed researchers to study the direct effects of cocaine on babies which included low birth weight and congenital anomalies.

Background: Precise manipulation of gene expression with temporal and spatial control is essential for functional analysis and determining cell lineage relationships in complex biological systems. The cyclic recombinase (Cre)‐loxP system is commonly used for gene manipulation at desired times and places. However, specificity is dependent on the availability of tissue‐ or cell‐specific regulatory elements used in combination with Cre. Here, we present CreLite, an optogenetically controlled Cre system using red light in developing zebrafish embryos. Results: Cre activity is disabled by splitting Cre and fusing with the Arabidopsis thaliana red light‐inducible binding partners, PhyB and PIF6. Upon red light illumination, the PhyB‐CreC and PIF6‐CreN fusion proteins come together in the presence of the cofactor phycocyanobilin (PCB) to restore Cre activity. Red light exposure of zebrafish embryos harboring a Cre‐dependent multicolor fluorescent protein reporter injected with CreLite mRNAs and PCB resulted in Cre activity as measured by the generation of multispectral cell labeling in several different tissues. Conclusions: Our data show that CreLite can be used for gene manipulations in whole embryos or small groups of cells at different developmental stages, and suggests CreLite may also be useful for temporal and spatial control of gene expression in cell culture, ex vivo organ culture, and other animal models. Key Findings: Created CreLite, an optogenetically-controlled Cre system using red light.Cre activity is disabled by splitting Cre and fusing with red light-inducible binding proteins.Upon red light illumination, the Cre fusion proteins come together to restore Cre activity.Demonstrate CreLite can be used for gene manipulations in whole zebrafish embryos or small groups of cells at different developmental stages.Findings suggest CreLite may also be useful for temporal and spatial control of gene expression in cell culture, ex vivo organ culture, and other animal models [ABSTRACT FROM AUTHOR]

Adult C. elegans germline stem cells (GSCs) and mouse embryonic stem cells (mESCs) exhibit a non-canonical cell cycle structure with an abbreviated G1 phase and phase-independent expression of Cdk2 and cyclin E. Mechanisms that promote the abbreviated cell cycle remain unknown, as do the consequences of not maintaining an abbreviated cell cycle in these tissues. In GSCs, we discovered that loss of gsk-3 results in reduced GSC proliferation without changes in differentiation or responsiveness to GLP-1/Notch signaling. We find that DPL-1 transcriptional activity inhibits CDK-2 mRNA accumulation in GSCs, which leads to slower S-phase entry and progression. Inhibition of dpl-1 or transgenic expression of CDK-2 via a heterologous germline promoter rescues the S-phase entry and progression defects of the gsk-3 mutants, demonstrating that transcriptional regulation rather than post-translational control of CDK-2 establishes the abbreviated cell cycle structure in GSCs. This highlights an inhibitory cascade wherein GSK-3 inhibits DPL-1 and DPL-1 inhibits cdk-2 transcription. Constitutive GSK-3 activity through this cascade maintains an abbreviated cell cycle structure to permit the efficient proliferation of GSCs necessary for continuous tissue output. [ABSTRACT FROM AUTHOR]