High impact information on Gravitation

• The latter filaments differed from those in the low-speed pellet in that they could not be depolymerized by Ca2+ and could not be sedimented at low g forces even from Triton X-100 lysates of platelets that had been activated with thrombin [1].
• Additionally, vertically grown arg1-2 roots appear to accumulate a greater amount of auxin in an expanded domain of the root cap compared with the wild type, and no detectable lateral auxin gradient develops across mutant root caps in response to gravistimulation [2].
• We observed a transient 5-fold increase in inositol 1,4,5-trisphosphate (IP3) within 10 s of gravistimulation in the lower half of the pulvinus, indicating that the positional change was sensed immediately [3].
• Our data indicate the involvement of IP3 and inositol phospholipids in both short- and long-term responses to gravistimulation [3].
• Additionally, phosphatidylinositol 4-phosphate 5-kinase activity in the lower pulvinus half increased transiently within 10 min of gravistimulation, suggesting that the increased IP3 production was accompanied by an up-regulation of phosphatidylinositol 4, 5-bisphosphate biosynthesis [3].

Biological context of Gravitation

• Interaction of fibrinogen with the integrin alpha IIb beta 3 induces platelet aggregation, transmembrane signaling, and the formation of integrin-rich cytoskeletal complexes that can be sedimented from detergent lysates at low g-forces [4].
• Here, we investigate auxin and gravity signal transduction by demonstrating that the endogenous signaling molecules nitric oxide (NO) and cGMP mediate responses to gravistimulation in primary roots of soybean (Glycine max) [5].
• Increasing the g force of centrifugation from 500 xg to 3,000 xg resulted in significantly less TGF-beta1, but more EGF and vitamin A. Cell proliferation was better supported by serum prepared with 3,000 xg and diluted with BSS [6].
• In order to prove whether gravistimulation is coupled with second messenger production (cyclic AMP: hyperpolarization, cyclic GMP: depolarization) Paramecium was fixated under variable accelerations (1 x g, 9 x g and 10(-4) x g) on a centrifuge and during a sounding rocket flight (TEXUS 39) [7].
• Recent investigations using modern techniques have generated findings consistent with the classical theory, including confirmation of asymmetrical distribution of polar auxin transport carriers, molecular evidence for auxin asymmetry following gravistimulation, and generation of auxin response mutants with predictable lesions in gravitropism [8].

Anatomical context of Gravitation

• Similar results were obtained when the actin filament content of discoid platelets was measured by sedimentation of filaments from Triton X-100 lysates at high g forces (145,000 g for 45 min) [9].
• Transcripts coding for calreticulin and calmodulin were recruited into polyribosomes within 15 min of gravistimulation [10].
• CD caused fragmentation of the actin cytoskeleton and delayed amyloplast displacement following gravistimulation [11].
• The responsiveness of the cervical and thoracic smooth muscle to methacholine was 16.4 and 16.3 g force/mm2, respectively, at an EC50 methacholine [12].
• The goal of this study has been to determine whether estradiol (E(2)) and dihydrotesterone (DHT) alter human umbilical vein ECs (HUVECs) responses to short term (10 min) hypergravity (1-3 g) mimicking the g force experienced by astronauts during liftoff [13].

Associations of Gravitation with chemical compounds

• Seven day old etiolated pea epicotyls were loaded symmetrically with 3H-indole 3-acetic acid (IAA) or 45Ca2+, then subjected to 1.5 hours of 1g gravistimulation [14].
• Also, after dark pretreatment, significant bending responses following hormone application were observed in vertical segments with or without added sucrose, while gravistimulation produced a response only if segments were given sucrose [15].
• Gravistimulation increased ethylene production in both lower and upper halves of the stems with much higher levels observed in the lower half [16].
• After ten days, they were centrifuged at gravities (g) of 1.3-27 for 24 h in a CO2 incubator [17].
• The homogenous symmetric expression of the cytokinin-responsive promoter in vertical root caps rapidly changed within less than 30 min of gravistimulation into an asymmetrical activation pattern, visualized as a lateral, distinctly stained, concentrated spot on the new lower root side of the cap cells [18].

Gene context of Gravitation

• AGR1 transcripts were localized to the root distal elongation zone, a region undergoing a curvature response upon gravistimulation [19].
• Within 15 min of gravistimulation, total levels of transcripts coding for calreticulin and calmodulin were elevated 5-fold in maize pulvinus total RNA [10].
• The transgenic roots were shown to have altered calcium sensitivity in controlling gravitropic response, a reduction in basipetal indole-3-acetic acid transport, and a delay in the asymmetric auxin-induced beta-glucuronidase expression with gravistimulation as compared to the controls [20].
• X-ray diffraction patterns show that the vesicles are stable in the absence of myelin basic protein, even under high g-forces [21].
• One of the ACS genes (Am-ACS3) was abundantly expressed in the bending zone cortex at the lower side of the stems within 2 h of gravistimulation [16].

Analytical, diagnostic and therapeutic context of Gravitation

• Also, we examined the influence of different G forces and centrifugation times on the retention behavior of the platelets in citrated platelet-rich plasma (PRP) and whole blood (WB) [22].

References