Potential Role of Sponge Spicules in Influencing the Silicon Biogeochemistry of Florida Lakes

1993 ◽  
Vol 50 (2) ◽  
pp. 296-302 ◽  
Author(s):  
Daniel J. Conley ◽  
Claire L. Schelske
Keyword(s):  
Amorphous Silica ◽  
Biogenic Silica ◽  
Time Course ◽  
Potential Role ◽  
Complete Dissolution ◽  
Sediment Samples ◽  
Florida Lakes ◽  
Sponge Spicules ◽  
Time Required

Amorphous silica, e.g. biogenic silica (BSi), contained in diatoms and in sponge spicules was estimated by time course extraction from surficial sediment samples of 82 Florida lakes. Separation of diatom BSi from sponge BSi was based on the observation that diatoms completely dissolve within 2 h of digestion at 85 °C in 1% Na2CO3 whereas sponge spicules, which are generally larger than diatoms, take longer to dissolve. Sponge samples from four lakes in northern Wisconsin ranged widely in the time required to dissolve completely (1.5–12 h), but no significant differences were observed in the rates of dissolution among the lakes. In Florida lake sediments, diatom BSi averaged 49.2 (± 48.4) mg∙g−1 and sponge BSi averaged 31.5 (± 35.8) mg∙g−1, with sponge BSi comprising on average 40% of the total amorphous silica extracted. The procedure for separating diatom BSi from sponge BSi underestimates sponge BSi because smaller and/or lightly silicified components of sponges are completely dissolved early in the digestion. However, because sponge spicules comprise a significant fraction of total amorphous silica extracted, we hypothesize that sponge spicules, which on average are larger than diatoms and require a longer time for complete dissolution, may constitute an important sink for BSi in Florida lakes.

Regeneration of vascular tissue through redifferentiation of interxylary phloem after complete girdling in Aquilaria sinensis

IAWA Journal ◽  
2021 ◽  
pp. 1-16
Author(s):  
Bei Luo ◽  
Arata Yoshinaga ◽  
Tatsuya Awano ◽  
Keiji Takabe ◽  
Takao Itoh
Keyword(s):  
Time Course ◽  
Potential Role ◽  
Vascular Tissue ◽  
Secondary Xylem ◽  
Vascular Cambium ◽  
Aquilaria Sinensis ◽  
Phloem Fibers ◽  
Interxylary Phloem ◽  
Time Course Study

Abstract We studied the time-course of stem response for six months following complete girdling in branches of Aquilaria sinensis to determine the potential role of interxylary phloem (IP) in this response. It was found that the vascular cambium, as well as its derivative secondary xylem and phloem, regenerated fully through redifferentiation of IP. We confirmed that vascular cambium regenerated within one month after girdling based on observation of new vessels, IP, and secondary phloem fibers. The time-course study showed that IPs made connections with each other, merged, and became larger through the proliferation of IPs parenchyma cells and the cleaving of secondary xylem in a narrow zone 400 to 1000 μm deep inside the girdled edge. This led to the formation of a complete circular sheath of vascular cambium, followed by the regeneration of vascular tissue. It is worth noting that the secondary xylem is regenerated always following the formation of a thick belt of wound xylem.

Abstract 105: Platelet-Neutrophil Aggregates play a crucial role in regulating vasculitis in Kawasaki Disease

Circulation ◽  
2015 ◽  
Vol 131 (suppl_2) ◽  
Author(s):  
Kentaro Ueno
Keyword(s):  
Kawasaki Disease ◽  
Crucial Role ◽  
Bacterial Infections ◽  
Time Course ◽  
Acute Inflammation ◽  
Potential Role ◽  
Platelet Factor ◽  
Normal Volunteers ◽  
Inflammatory Activation

Objective: Circulating platelet-neutrophil aggregates play a crucial role in amplifying acute inflammation and could promote adverse effects involving vascular injury. The aim of this study was to clarify the role of platelet-neutrophil aggregates in patients with Kawasaki disease (KD). Methods: We analyzed 40 patients with KD (30 intravenous immunoglobulin [IVIG] responders and 10 IVIG non-responders), 7 febrile patients with bacterial infections, and 9 normal volunteers. Thirty-three patients with KD were treated with IVIG alone, and remaining seven were treated with IVIG plus prednisolone. We evaluated the rate of platelet-neutrophil aggregates and measured the platelet factor 4 (PF4) and β-thromboglobulin (β-TG) levels in patients with KD. Results: The rate of platelet-neutrophil aggregates was significantly higher in patients with KD than in both patients with bacterial infection and normal volunteers. There was a trend toward increased rate of platelet-neutrophil aggregates within 2 or 3 days after IVIG than before IVIG. The rate of platelet-neutrophil aggregates was significantly higher in patients who showed coronary artery abnormalities (CAA) than in those who showed without CAA and was correlated with PF4 and β-TG levels in patients with KD. Comparing time course analysis, the rate of platelet-neutrophil aggregates was significantly decreased in patients treated with IVIG plus prednisolone than in those treated with IVIG alone. Conclusions: Our findings demonstrate that platelet-neutrophil aggregates play a crucial role in regulating vasculitis, and are involved in the development of CAA. Additional prednisolone treatment in the acute phase of KD might have a potential role in inhibiting amplified reciprocal inflammatory activation by suppressing platelet-neutrophil aggregates.

Effects of CSF ANG II and AVP on sweating in the heat-stressed patas monkey

1989 ◽  
Vol 67 (1) ◽  
pp. 134-140 ◽  
Author(s):  
M. D. Owen ◽  
R. D. Matthes ◽  
C. V. Gisolfi
Keyword(s):  
Cerebrospinal Fluid ◽  
Rectal Temperature ◽  
Time Course ◽  
Potential Role ◽  
Sweat Rate ◽  
Ang Ii ◽  
Erythrocebus Patas ◽  
Patas Monkey ◽  
Artificial Cerebrospinal Fluid

Increasing cerebrospinal fluid [Na+] reduces sweat rate (msw) in the heat-stressed patas monkey (Erythrocebus patas). This study determined the potential role of two neuropeptides, angiotensin II (ANG II) and arginine vasopressin (AVP), in mediating this response. Artificial cerebrospinal fluid, containing either ANG II or AVP, was infused into the third cerebral ventricle of lenperone-tranquilized monkeys (n = 4) exposed to 41 +/- 2 degrees C. Solutions were infused at 16.5 microliters/min for 25 min (total vol approximately 413 microliters). ANG II (1.25, 2.5, 5, and 10 ng/microliters) tended to decrease .msw. However, during infusion, only the decline at 10 min associated with the 1.25-ng/microliters dose (26%) was different (P less than 0.004) from control. This dose elevated (P less than 0.004) core rectal temperature by 1.14 degrees C at 20 min postinfusion. In contrast, AVP (0.5 and 1.5 micrograms/microliters artificial cerebrospinal fluid) had no significant effect on .msw compared with control infusions. Both doses of AVP produced a slight but significant increase in rectal temperature of 0.14 and 0.22 degrees C, respectively, at 20 min postinfusion. In conclusion, the magnitude and time course of the change in .msw with central ANG II suggest that it does not act as the sole mediator of the decline in .msw observed with elevated cerebrospinal fluid [Na+]. The minimal effects produced by third ventricular AVP exclude this route as a means by which AVP could modulate .msw during dehydration.

POPDC proteins and cardiac function

2019 ◽  
Vol 47 (5) ◽  
pp. 1393-1404 ◽  
Author(s):  
Thomas Brand
Keyword(s):  
Potential Role ◽  
Striated Muscle ◽  
Short Review ◽  
Effector Proteins ◽  
Muscle Disease ◽  
Disease Genes ◽  
Protein Protein Interaction ◽  
Interaction Partners ◽  
And Function

Abstract The Popeye domain-containing gene family encodes a novel class of cAMP effector proteins in striated muscle tissue. In this short review, we first introduce the protein family and discuss their structure and function with an emphasis on their role in cyclic AMP signalling. Another focus of this review is the recently discovered role of POPDC genes as striated muscle disease genes, which have been associated with cardiac arrhythmia and muscular dystrophy. The pathological phenotypes observed in patients will be compared with phenotypes present in null and knockin mutations in zebrafish and mouse. A number of protein–protein interaction partners have been discovered and the potential role of POPDC proteins to control the subcellular localization and function of these interacting proteins will be discussed. Finally, we outline several areas, where research is urgently needed.

The Effect of Path Length and Display Size on Memory for Spatial Information

2012 ◽  
Vol 59 (3) ◽  
pp. 147-152 ◽  
Author(s):  
Katherine Guérard ◽  
Sébastien Tremblay
Keyword(s):  
Path Length ◽  
Potential Role ◽  
Spatial Information ◽  
Recall Performance ◽  
Minor Role ◽  
Length Effect ◽  
Serial Memory ◽  
Fixed Reference ◽  
A Minor

In serial memory for spatial information, some studies showed that recall performance suffers when the distance between successive locations increases relatively to the size of the display in which they are presented (the path length effect; e.g., Parmentier et al., 2005) but not when distance is increased by enlarging the size of the display (e.g., Smyth & Scholey, 1994). In the present study, we examined the effect of varying the absolute and relative distance between to-be-remembered items on memory for spatial information. We manipulated path length using small (15″) and large (64″) screens within the same design. In two experiments, we showed that distance was disruptive mainly when it is varied relatively to a fixed reference frame, though increasing the size of the display also had a small deleterious effect on recall. The insertion of a retention interval did not influence these effects, suggesting that rehearsal plays a minor role in mediating the effects of distance on serial spatial memory. We discuss the potential role of perceptual organization in light of the pattern of results.

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