Effect of Tryptophan Analogs on Derepression of the \u3cem\u3eEscherichia coli\u3c/em\u3e Tryptophan Operon by Indole-3-Propionic Acid

The abilities of 14 tryptophan analogs to repress the tryptophan (trp) operon have been studied in Escherichia coli cells derepressed by incubation with 0.25 mM indole-3-propionic acid (IPA). trp operon expression was monitored by measuring the specific activities of anthranilate synthase (EC 4.1.3.27) and the tryptophan synthase (EC 4.2.1.20) β subunit. Analogs characterized by modification or removal of the α-amino group or the α-carboxyl group did not repress the trp operon. The only analogs among this group that appeared to interact with the trp aporepressor were IPA, which derepressed the trp operon, and d-tryptophan. Analogs with modifications of the indole ring repressed the trp operon to various degrees. 7-Methyl-tryptophan inhibited anthranilate synthase activity and consequently derepressed the trp operon. Additionally, 7-methyltryptophan prevented IPA-mediated derepression but, unlike tryptophan, did so in a non-coordinate manner, with the later enzymes of the operon being relatively more repressed than the early enzymes. The effect of 7-methyltryptophan on IPA-mediated derepression was likely not due to the interaction of IPA with the allosteric site of anthranilate synthase, even though feedback-resistant mutants of anthranilate synthase were partially resistant to derepression by IPA. The effect of 7-methyltryptophan on derepression by IPA was probably due to the effect of the analog-aporepressor complex on trp operon expression

Postpartum Opioid Use Following Vaginal Deliveries with No or Minor Obstetric Perineal Lacerations

Background: Recommendations for management of pain following vaginal delivery are not specific and do not differentiate patients based on the degree of perineal trauma. Our objective is to describe patterns of postpartum opioid use in women with no or minor perineal trauma. Methods: This is a retrospective cohort study describing the characteristics of opioid analgesia usage among women with no or minor perineal lacerations at the time of vaginal delivery in a university affiliated regional hospital. Results: For the 6-month study period, 433 patients were eligible for inclusion. Of these, 423 (97.69%) were ordered as needed narcotics during their post-partum hospitalization. Of women with an as needed narcotic prescribed, 285 (65.82%) used at least one dose of narcotics while hospitalized. Significant patient characteristics of women using opioids during their inpatient post-partum course included those who used epidural analgesia during labor (p=0.009) and primiparous patients (p=0.05). Thirty-five of the women included in the study received a prescription for opioid analgesics at the time of discharge (8.08%). Significant findings among these women include increasing maternal age (p=0.007). Non-academic physicians with resident coverage were 3.1 times more likely to prescribe opioids at discharge compared to academic physicians with residents and non-academic physicians without resident coverage. Conclusions: Focusing specifically on women with no or minor perineal lacerations at the time of delivery, our findings indicate that if given the option of opioids analgesia during their hospitalization, many women will request at least one dose of opioid analgesia, but rarely require opioids after discharge

Detection of the argonaute protein Ago2 and microRNAs in the RNA induced silencing complex (RISC) using a monoclonal antibody

MicroRNAs (miRNAs) are short RNA molecules responsible for post-transcriptional gene silencing by the degradation or translational inhibition of their target messenger RNAs (mRNAs). This process of gene silencing, known as RNA interference (RNAi), is mediated by highly conserved Argonaute (Ago) proteins which are the key components of the RNA induced silencing complex (RISC). In humans, Ago2 is responsible for the endonuclease cleavage of targeted mRNA and it interacts with the mRNAbinding protein GW182, which is a marker for cytoplasmic foci referred to as GW bodies (GWBs). We demonstrated that the antiAgo2 monoclonal antibody 4F9 recognized GWBs in a cell cycle dependent manner and was capable of capturing miRNAs associated with Ago2. Since Ago2 protein is the effector protein of RNAi, anti-Ago2 monoclonal antibody may be useful in capturing functional miRNAs

Design and testing of ultralite fabric reflux tubes

This paper describes the design, fabrication, and testing of Ultralite Fabric Reflux Tubes intended to provide thermal control for a Lunar Colony. The Ultralite Fabric Reflux Tubes, under this phase of development, are constructed of thin-walled copper liners overwrapped with aluminoborosilicate fabric. These devices were constructed and tested in air at the Pacific Northwest Laboratory and subsequently taken to the NASA Johnson Space Center for thermal vacuum experimentation

The function of the alula in avian flight

The alula is a small structure located at the joint between the hand-wing and arm-wing of birds and is known to be used in slow flight with high angles of attack such as landing. It is assumed to function similarly to a leading-edge slat that increases lift and delays stall. However, in spite of its universal presence in flying birds and the wide acceptance of stall delay as its main function, how the alula delays the stall and aids the flight of birds remains unclear. Here, we investigated the function of alula on the aerodynamic performance of avian wings based on data from flight tasks and wind-tunnel experiments. With the alula, the birds performed steeper descending flights with greater changes in body orientation. Force measurements revealed that the alula increases the lift and often delays the stall. Digital particle image velocimetry showed that these effects are caused by the streamwise vortex, formed at the tip of the alula, that induces strong downwash and suppresses the flow separation over the wing surface. This is the first experimental evidence that the alula functions as a vortex generator that increases the lift force and enhances manoeuvrability in flights at high angles of attack.open1

Long-term effects of chronic light pollution on seasonal functions of European blackbirds (turdus merula)

Light pollution is known to affect important biological functions of wild animals, including daily and annual cycles. However, knowledge about long-term effects of chronic exposure to artificial light at night is still very limited. Here we present data on reproductive physiology, molt and locomotor activity during two-year cycles of European blackbirds (Turdus merula) exposed to either dark nights or 0.3 lux at night. As expected, control birds kept under dark nights exhibited two regular testicular and testosterone cycles during the two-year experiment. Control urban birds developed testes faster than their control rural conspecifics. Conversely, while in the first year blackbirds exposed to light at night showed a normal but earlier gonadal cycle compared to control birds, during the second year the reproductive system did not develop at all: both testicular size and testosterone concentration were at baseline levels in all birds. In addition, molt sequence in light-treated birds was more irregular than in control birds in both years. Analysis of locomotor activity showed that birds were still synchronized to the underlying light-dark cycle. We suggest that the lack of reproductive activity and irregular molt progression were possibly the results of i) birds being stuck in a photorefractory state and/or ii) chronic stress. Our data show that chronic low intensities of light at night can dramatically affect the reproductive system. Future studies are needed in order to investigate if and how urban animals avoid such negative impact and to elucidate the physiological mechanisms behind these profound long-term effects of artificial light at night. Finally we call for collaboration between scientists and policy makers to limit the impact of light pollution on animals and ecosystems