Maternal age does not affect tetrahydrocannabinol's in utero actions in rats

The potential contribution of maternal age to tetrahydrocannabinol's (THC) in utero effects in rats was studied. Pregnant animals were intubated with 25, 10 or 0 mg/kg of THC from gestation day six to parturition. Animals in the 10 and 0 mg/kg groups were pair fed to those given the 25 mg/kg dose. Each series of doses was administered to females three, four or six months of age. THC lowered maternal weight gain and weights of offspring at birth and at 21 days of age, but did not affect litter size, spontaneous alternation or passive avoidance learning in offspring. Increased maternal age was associated with smaller litter size and lower birth weight and weight at 21 days, but did not interact significantly with THC.     

Patterns of sequence variation in the mitochondrial D-loop region of shrews

Direct sequencing of the mitochondrial displacement loop (D-loop) of shrews (genus Sorex) for the region between the tRNA(Pro) and the conserved sequence block-F revealed variable numbers of 79-bp tandem repeats. These repeats were found in all 19 individuals sequenced, representing three subspecies and one closely related species of the masked shrew group (Sorex cinereus cinereus, S. c. miscix, S. c. acadicus, and S. haydeni) and an outgroup, the pygmy shrew (S. hoyi). Each specimen also possessed an adjacent 76-bp imperfect copy of the tandem repeats. One individual was heteroplasmic for length variants consisting of five and seven copies of the 79-bp tandem repeat. The sequence of the repeats is conducive to the formation of secondary structure. A termination-associated sequence is present in each of the repeats and in a unique sequence region 5' to the tandem array as well. Mean genetic distance between the masked shrew taxa and the pygmy shrew was calculated separately for the unique sequence region, one of the tandem repeats, the imperfect repeat, and these three regions combined. The unique sequence region evolved more rapidly than the tandem repeats or the imperfect repeat. The small genetic distance between pairs of tandem repeats within an individual is consistent with a model of concerted evolution. Repeats are apparently duplicated and lost at a high rate, which tends to homogenize the tandem array. The rate of D- loop sequence divergence between the masked and pygmy shrews is estimated to be 15%-20%/Myr, the highest rate observed in D-loops of mammals. Rapid sequence evolution in shrews may be due either to their high metabolic rate and short generation time or to the presence of variable numbers of tandem repeats.      

大鼠胼胝体内神经肽Y免疫反应阳性纤维的发育

本实验用免疫组织化学ＡＢＣ法研究了大鼠胼胝体内神经肽Ｙ免疫反应阳性（ＮＰＹ－ＩＲ）纤维的生后发育。结果发现,许多ＮＰＹ－ＩＲ纤维在大鼠出生时便存在于胼胝体内。ＮＰＹ－ＩＲ胼胝体纤维的密度在生后１周内继续逐渐增高,在第２周内达到最高峰。之后,ＮＰＹ－ＩＲ胼胝体纤维的密度逐渐下降,至第３周末时接近成年时的水平,即仅有少量ＮＰＹ－ＩＲ纤维存在于胼胝体内。这些结果提示在大鼠早期生后发育过程中许多ＮＰＹ－ＩＲ胼胝体纤维是暂时性的,其作用可能与大脑皮质的机能发育有关。     

Selective activation of cyclic AMP dependent protein kinase by calcitonin in a calcitonin secreting lung cancer cell line

When the F1-ATPase from the thermophilic bacterium, PS3, was inactivated by 90% with 7-chloro-4-nitro[14C]benzofurazan ([14C]Nbf-Cl) at pH 7.3 and then gel-filtered, 1.25 mols of [14C]Nbf-O-Tyr and less than 0.1 mol of Nbf-N-Lys were formed per mol of enzyme. After adjusting the pH of the gel-filtered, modified enzyme to 9.0 and incubating it for 14 hrs. at 23 degrees C to promote O----N migration, 0.68 mol of Nbf-N-Lys were formed per mol of enzyme while about 16% of the original activity reappeared. Isolation of the subunits after the O----N migration showed that 90% of the incorporated 14C was present in the beta subunit, which contained 0.21 mols of [14C]Nbf-N-Lys per mol. A tryptic peptide which contained the majority of the 14C incorporated into the beta subunit was isolated and subjected to automatic amino acid sequence analysis contained 38 residues. The amino acid sequence immediately around the lysine residue labeled with [14C]Nbf-, K*, was found to be: ...I-G-L-F-G-G-A-G-V-G-K*-T-V-L-I-G... .     

Optimal muscular coordination strategies for jumping

This paper presents a detailed analysis of an optimal control solution to a maximum height squat jump, based upon how muscles accelerate and contribute power to the body segments during the ground contact phase of jumping. Quantitative comparisons of model and experimental results expose a proximal-to-distal sequence of muscle activation (i.e. from hip to knee to ankle). We found that the contribution of muscles dominates both the angular acceleration and the instantaneous power of the segments. However, the contributions of gravity and segmental motion are insignificant, except the latter become important during the final 10% of the jump. Vasti and gluteus maximus muscles are the major energy producers of the lower extremity. These muscles are the prime movers of the lower extremity because they dominate the angular acceleration of the hip toward extension and the instantaneous power of the trunk. In contrast, the ankle plantarflexors (soleus, gastrocnemius, and the other plantarflexors) dominate the total energy of the thigh, though these muscles also contribute appreciably to trunk power during the final 20% of the jump. Therefore, the contribution of these muscles to overall jumping performance cannot be neglected. We found that the biarticular gastrocnemius increases jump height (i.e. the net vertical displacement of the center of mass of the body from standing) by as much as 25%. However, this increase is not due to any unique biarticular action (e.g. proximal-to-distal power transfer from the knee to the ankle), since jumping performance is similar when gastrocnemius is replaced with a uniarticular ankle plantarflexor.     

Transplantation of Hymenolepis diminuta into naive, immune and irradiated mice.

Almost 100% of 7- to 10-day-old Hymenolepis diminuta became established when surgically transplanted from donor mice into the duodenum of naive recipient mice. Transplanted tapeworms survived 8-12 days, by which time they had survived much longer in total than they would have done in the donor. Mice previously immunized by a primary infection rejected transplants within 4 days. Sub-lethal irradiation (550 rad) delayed rejection by immune mice but such mice still rejected worms much more quickly than did naive mice. Surgery was shown to delay by 2-3 days the rejection of worms by naive mice, and the importance of circumventing surgery by administering the worms per os is emphasized. Prospects for reconstituting irradiated immune mice are considered vis-à-vis work with nematodes, and the differences which, on present knowledge, appear to exist between nematode and cestode rejection are briefly discussed.