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Cholinesterase activity in the neural retina of the developing chick
Developmental changes in the enzymes acetylcholinesterase
(EC 3.1.1.7) and pseudocholinesterase (EC 3.1.1.8) were
examined in ovo and in vitro in the neural retina of the
developing chick. In addition, investigations of cellular
interactions and hormones as possible control mechanisms of
enzyme synthesis were made.
The specific activity of acetylcholinesterase, a marker
of neuronal differentiation, increased from 6 to 9 days,
leveled off from 9 to 11 days, and increased sharply from
11 to 18 days. This pattern correlates with periods of
histogenesis in the retina. Cell number and protein content
per retina were also examined.
The specific activity of pseudocholinesterase, a possible
glial cell enzyme in this tissue, remained relatively
constant during development.
Acetylcholinesterase and pseudocholinesterase activities
increased for several days in cultures of intact
retinas derived from 6-, 8-, 10 -, and 14-day embryos.
However, the pattern of the acetylcholinesterase activity
increase varied with the age of the embryo. Mitotically
active retinas (from 6- and 8-day embryos) expressed an increase
in acetylcholinesterase activity in culture similar
to that in vivo; although retinas undergoing differentiation
(from 10- and 14-day embryos) also expressed a continued
increase in acetylcholinesterase activity in culture,
the activities were lower than those in vivo. Cultures of
retinas from 6-, 8-, 10-, and 14-day embryos showed increasing
pseudocholinesterase activity in culture, which was also
lower than that in vivo.
Enzyme activities in aggregate, monolayer, and intact
retina cultures derived from 6-day embryos were compared to
ascertain whether they were dependent on the formation of
cellular associations in culture. All cultures exhibited
increases in acetylcholinesterase activity similar to retinas
in vivo, suggesting that cellular associations do not affect
acetylcholinesterase activity nor its age- dependent increases.
Pseudocholinesterase activity also increased in all three
culture environments, but the activity was always lower than
in retinas in vivo.
Two hormones were investigated as possible control
mechanisms for these enzymes. Hydrocortisone did not affect
total cholinesterase activity in cultures of retinas from
10-, 12-, 14-, or 16-day embryos.
Treatment of retinal cells with thyroxine resulted in
increased acetylcholinesterase and pseudocholinesterase
activities at most ages tested. The maximum increases of
acetylcholinesterase (30%) and pseudocholinesterase (17%)
were in cultured retinas equivalent in age to 11 days in
vivo. Changes in enzyme activities were similar with short
(24 hr) or long (several days) thyroxine treatments.
When the serum content of the tissue culture medium was decreased, both acetylcholinesterase and pseudocholinesterase
activities decreased. However, substitution
of thyroxine for serum in the tissue culture medium returned
acetylcholinesterase activity to the control level in cultures
of retinas from embryos of 10 days or older; cultures
of retinas from embryos less than 10 days exhibited acetylcholinesterase
activities midway between those of control
cultures and cultures without serum. When thyroxine was
substituted for serum, pseudocholinesterase activity was
greater than in cultures without serum, but less than control
values at all ages investigated; therefore, thyroxine
only partially replaced serum in stimulating pseudocholinesterase
activity.
The value of the retina as an experimental tissue for
the study of cholinergic synapse formation in vitro is discussed.
This study reports that acetylcholinesterase activity
increased in vitro independent of cellular associations.
This result is discussed in relation to published data on
acetylcholinesterase activity in brain tissues and on glutamine
synthetase activity in retina tissue
Exile Vol. XXXIV No. 1
Rock by Cam Martin (cover)
New Arrival by Kent Lambert 3
Le Sacre Du Printemps by David Zivan 4
Nightscape by Cam Martin 5
A Cry For Life by Kent Lambert 7-8
Untitled by Grant Young 9
Crazy Circle by Melissa Wellington 10
Untitled by Shelley Dickerson 13
*The Tall Boy by Lauren Williams 15-19
*Untitled by Shelley Dickerson 21
Our Native Images by Cam Martin 23-38
Untitled by Lauran Hannan 39
Psych 100 by David Zivan 41
Routine by Lauren Williams 42-47
Untitled by Shelley Dickerson 49
A Man\u27s Descent to Hell, by Chris Rynd 51-53
Separation by David Zivan 54
Boat by Cynthia Hoag 55
Passage by Rosemary Walsh 57
Whales by Zachary Smith 58
Untitled by Lauren Hannan 59
Contributor Notes 61
Editorial decision is shared equally amoung [sic] the Editorial Board members. - title page
* indicates contest winner -2
NOTE: The poem Crazy Circle by Melissa Wellington is listed as page 10 in the published table of contents but actually appears on page 11
Functional Heterologous Expression of an Engineered Full Length Cipa from Clostridium Thermocellum in Thermoanaerobacterium Saccharolyticum
Background: Cellulose is highly recalcitrant and thus requires a specialized suite of enzymes to solubilize it into fermentable sugars. In C. thermocellum, these extracellular enzymes are present as a highly active multi-component system known as the cellulosome. This study explores the expression of a critical C. thermocellum cellulosomal component in T. saccharolyticum as a step toward creating a thermophilic bacterium capable of consolidated bioprocessing by employing heterologously expressed cellulosomes. Results:We developed an inducible promoter system based on the native T. saccharolyticum xynA promoter, which was shown to be induced by xylan and xylose. The promoter was used to express the cellulosomal component cipA*, an engineered form of the wild-type cipAfrom C. thermocellum. Expression and localization to the supernatant were both verified for CipA*. When a ΔcipA mutant C. thermocellum strain was cultured with a CipA*-expressing T. saccharolyticum strain, hydrolysis and fermentation of 10 grams per liter SigmaCell 101, a highly crystalline cellulose, were observed. This trans-species complementation of a cipA deletion demonstrated the ability for CipA* to assemble a functional cellulosome. Conclusion: This study is the first example of an engineered thermophile heterologously expressing a structural component of a cellulosome. To achieve this goal we developed and tested an inducible promoter for controlled expression in T. saccharolyticum as well as a synthetic cipA . In addition, we demonstrate a high degree of hydrolysis (up to 93%) on microcrystalline cellulose
Exile Vol. XXXV No. 2
Peter Goes Groovy, by Carolyn Bern (cover)
I Hate Poetry by Craig Bagno 1
Truancy by Richard Latimer 2
I ate a Star Last Night by Rory Herbster 3
Delivery by Amy Judge 4
Untitled by Sue McLain 5
Road Signs by Richard Latimer 7-8
Haiku for Me to Possess by Shannon J. Salser 9
Patches by Michael Payne 10
Untitled by Laura Johnson 11
He by Kent Lambert 13
At the Corner Grill by Lynn Pendleton 14-15
Black Licorice by Richard Latimer 16-17
Blue Shirt by Michael Payne 18
...Loves a Clown by Margaret Dawson 21-24
The Surreal Sonnet by Shannon J. Salser 26
Untitled by Mat Benson 27
Swimming Lessons by Richard Latimer 29
Communion by Amy Judge 30
Beth\u27s Last Funny Joke by Ted Gould 31-35
Hope for a Peaceful Coming Around by Shannon J. Salser 36
Untitled by Laura Johnson 37
A Child\u27s Moment by Peter Witonsky 39
Observation by Rosemary Walsh 40
Untitled by Carolyn Burns 41
To My Sister by Amy B. Judge 43
Ideas In Bloom by Randy Casden 44
Untitled by Deb Tily 45
A Child of Mind by Charles Riedinger 47
Ars Poetica by Rory Herbster 48
Untitled by Mat Benson 49
REPRINTS
Dancer by Bradford Cover 52
Skin Deep by Eric Whitney 53-55
Sunset by Chris Rynd 56
Editorial decision is shared equally among the Editorial Board Members -cover page
The editors of Exile would like to formally apologize to those contributors whose works were misprinted in the Fall issue. We have reprinted a few of the pieces that contained the most errors. -51
NOTE: An uncredited and untitled piece of artwork appears on page 19.
NOTE: Carolyn Bern (cover) Burns (41) and Berns (contributor notes) all appear to refer to the same artist
Exile Vol. XXXV No. 1
ARTWORK
Untitled by Eric Whitney (cover)
Untitled by Rory Herbster 7
Little Boy by Eric Whitney 45
FICTION
Through the Window Pane by Jennifer Read 4
to whom i may concern by Chris Campi 19
For Lack of Sleep by Amy Judge 26
Jonathan by Jim Cox 39
Skin Deep by Eric Whitney 51
NON-FICTION
A Theopoetic by Robert Marshall 11
POETRY
Clay Pot by Christopher Collette 1
Ars Poetica by Mans Agantyr 2
Bible Thumber by Chris Rynd 6
Play by Amy Judge 9
Satellites by Andrew C. Carinston 10
Music - Love? by Shammon J. Salser 15
Allusion by Rosemary Walsh 17
Self Portrait by Margaret Dawson 18
On Our Way by Lynn Pendleton 21
They called her Mitzi... by Jen Miller 22
Storms of Illusion by Kevin Merriman 23
Beauty by Andrew C. Carington 24
Thoughts of a Husband by Kent Lambert 25
The Music of the Sum by Zach Smith 31
Don\u27t Think by Mary Forsythe 32
Aspiration by Tim Emrick 33
Where We Go Together by Man Angantyr 35
Sunset by Chris Byrd 36
The Child of my Fatalism by Jennifer Peterson 37
Untitled by Kent Lambert 38
Terribly close to being... by Michael Payne 44
Anne Frank\u27s House by Mary Forsythe 47
Invitation by Kevin Merriman 48
Height Protest by Jen Miller 49
Dancer by Bradford Cover 50
Ars Poetica by Amy Judge 55
Editorial decision is shared equally among the Editorial Board members -title page
NOTE: The author of the poem Satellites is listed as Andrew C. Carinston in the published table of contents. This is likely a misspelling as there are four instances of an Andrew C. Carington elsewhere in this edition, including the attribution on the page where Satellites is published.
NOTE: The author of the poem Where We Go Together is listed as Man Angantyr in the published table of contents. This is likely a misspelling as there are four instances of an Mans Angantyr elsewhere in this edition, including the attribution on the pages where Where We Go Together is published.
NOTE: Chris Byrd is listed as the author of the poem Sunset in the published version. However a note in the received version indicates that the author is actually Chris Rynd, whose poem Bible Thumper is also published in this issue. No Chris Byrd is listed among the contributors to this issue.
NOTE: The author of the poem Music = Love? is listed as Shammon J. Salser in the published table of contents. This is likely a misspelling. Where Music = Love? appears the author is listed as Shannon J. Salser. The same is true of the contributors section.
NOTE: Though the published table of contents is followed here, the poem by Zach Smith that is published on page 31 is listed as The Music of the Sun on page 31