The periodic swarming of Anchistioides antiguensis

Observations from the jetty of the Biological Station, Bermuda, of the appearance of Anchistioides antiguensis (Schmitt) at the surface over a short period in 1934 and eight months in 1935 are recorded, and show definite periodicity sometimes of sufficient intensity to merit the term swarming.
The periodicity coincides with the two weeks of the lunar cycle when the moon wanes from the last quarter to the first quarter of the new cycle. It appears to consist of two maximum appearances separated by an interval of some days.
Direct lunar influence, sex and the reproductive period, the surface-temperature, wind and weather, and the state of the tide are shown to have no connexion with swarming.
An explanation is suggested based on the feeding habits and depending on the periodic activity of the worms that form the food. The double maximum of the swarming period is shown to represent two stages of growth.     

Molecular Imaging of CXCL12 Promoter-driven HSV1-TK Reporter Gene Expression

The C-X-C motif chemokine 12 (CXCL12, SDF1a) and its receptor, CXCR4, play a fundamental role in several biological processes, including hematopoiesis, cardiogenesis, cancer progression, and stem cell migration. Noninvasive monitoring of CXCL12 is highly desirable for optimizing strategies that combine mobilization of therapeutic cells to combat cancer or to assist in cardiac tissue repair after myocardial infarction. Here, we report on an MRI reporter gene system for directly monitoring CXCL12 expression in vivo. Glioma cells and human adipose-derived stem cells (hADSC) were transduced with the herpes simplex virus type-1-thymidine kinase (HSV1- tk) reporter gene expressed under the CXCL12 promoter. HSV1-tk expression resulted in accumulation of the PET tracer [¹²⁵I]FIAU in vitro and in vivo and induced cell death after ganciclovir treatment. Furthermore, the results show that conditional expression of the reporter gene can be induced by hypoxia in transduced cells. Transduced hADSC were incubated with the CEST MRI probe 5-methyl-5, 6- dihydrothymidine (5-MDHT) and transplanted into swine heart. Transplanted cells were clearly visible on Chemical Exchange Saturation Transfer (CEST) MRI using a 3T clinical scanner. Therefore, we conclude that it is possible to image CXCL12 expression with MRI in a large animal model, opening up a possible route to clinical translation.     

Positive selection and the molecular evolution of a gene of male reproduction, Acp26Aa of Drosophila

The gene for a male ejaculatory protein, Acp26Aa, in four sibling species of the Drosophila melanogaster subgroup has previously been shown to have a nonsynonymous rate (Ka) of nucleotide substitution that is indistinguishable from the synonymous rate (Ks). By examining this gene in two other species of this subgroup, we found that Ka is generally large and can sometimes be more than twice as large as Ks. This suggests that positive selection may be operating at this locus of male reproduction.