bluuebunny/crossref_metadata_2025 huggingface dataset:
Nicotine affects the expression of brain-derived neurotrophic factor mRNA and protein in the hippocampus of hypoxic newborn piglets
Authors: Andresen Jannicke Hanne , Løberg Else Marit , Wright Marianne , Goverud Ingeborg Løstegaard , Stray-Pedersen Babill , Saugstad Ola Didrik
Published: June 2009

Brain-derived neurotrophic factor (BDNF) is highly expressed in the developing brain. It has anti-apoptotic abilities, and protects the neonatal brain. In experimental settings in adult animals, pre-treatment with nicotine has shown increased BDNF levels, indicating a possible contribution to nicotine's anti-apoptotic effect. Apoptosis contributes to the development of brain damage in perinatal asphyxia. We examined the effects of nicotine on apoptosis-inducing factor (AIF), caspase-3 and BDNF in the hippocampus of a neonatal piglet model of global hypoxia. Forty-one anesthetized newborn piglets were randomized to one of four groups receiving different infusions after hypoxia (1) nicotine 130 μg/kg/h, 2) 260 μg/kg/h, 3) adrenaline, and 4) saline, all 2.6 mL/kg/h. Four hours after hypoxia they were euthanized. The left hemisphere/hippocampus was examined by histopathology and immunohistochemistry; the right hippocampus was analyzed using real time PCR. There was a significantly higher expression of BDNF mRNA and protein in the animals treated with nicotine 130 μg/kg/h vs. the saline treated group (mRNA P=0.038; protein P=0.009). There were no differences regarding AIF or caspase-3. We conclude that nicotine (130 μg/kg/h), infused over 1 h after global hypoxia in neonatal piglets, increases levels of both BDNF mRNA and protein in the hippocampus. This might imply neuroprotective effects of nicotine in asphyxiated neonates.
Increased inositol phosphoglycan P-type in the second trimester in pregnant women with type 2 and gestational diabetes mellitus
Authors: Scioscia Marco , Gumaa Khalid , Selvaggi Luigi E. , Rodeck Charles H. , Rademacher Thomas W.
Published: June 2009

A progressive insulin resistant state develops throughout human pregnancy. Inositol phosphoglycan P-type (P-IPG), a second messenger of insulin, was reported to negatively correlate with the degree of insulin resistance in non-pregnant diabetic subjects. Urinary levels of P-IPG were assessed in insulin resistant states during pregnancy such as gestational diabetes mellitus (GDM, n=44) and type 2 diabetes mellitus (type 2 DM, n=25) and in 69 normal pregnant women. Urinary levels of P-IPG were higher in GDM than controls with a positive trend of release throughout normal pregnancy (P<0.01). P-IPG excretion was higher in diabetic (GDM and type 2 DM) than in healthy women in the second trimester (P<0.05). A higher P-IPG urinary excretion occurs during the second trimester in pregnant women with clinically evident insulin resistance with a positive association with poor glycemic control.
Outpatient induction – how safe
Authors: Rath Werner H.
Published: June 2009

There is a world-wide interest in outpatient care. Induction of labor is commonly offered to women with prolonged pregnancy, and evidence from randomized controlled studies suggest that inpatient and outpatient induction achieve comparative maternal and fetal outcomes. However, safety data are very limited. Careful selections of appropriate patients as well as standardized monitoring protocols are essential before outpatient induction can be initiated. Uterine hyperstimulation with fetal heart rate deceleration and other maternal or fetal adverse events are rare but unpredictable. Unrecognized fetal hypoxia due to uterine contractions remains an unsolved problem after discharge from the hospital. The ideal method for outpatient cervical ripening is controversial. The local application of nitric oxide donors prior to induction might be a promising approach. Larger studies are necessary before widespread use of outpatient cervical ripening by prostaglandins or other cervical ripening agents can be advocated.
Umbilical cord insertion site in early gestation and development of placenta
Authors: Hasegawa Junichi , Matsuoka Ryu , Ichizuka Kiyotake , Sekizawa Akihiko , Okai Takashi
Published: June 2009

Aim: To study the relation of umbilical cord insertion (CI) site in early gestation and placental development from the chorion villosum.

Methods: We ultrasonically measured the distance between the internal cervical Os and the CI site (CID), the distance between the internal cervical Os and lower placenta edge (PLD), and placental thickness at early (10–12 weeks) and mid-gestation (18–20 weeks).

Results: CID in early gestation (CID-Early) correlated with CID in mid-gestation (r2=0.171; P<0.01). CID-Early correlated with PLD in mid-gestation (r2=0.093; P<0.01). Thickness of chorion villosum or placenta in early gestation did not correlate with that at mid-gestation. Increasing thickness of placenta was significantly higher in long CID-Early (≥20 mm) cases than short cases (<20 mm) (P<0.05).

Conclusions: The process of placental development and the placental location are affected by CI location at early gestation, and suggests that this process might be affected by poor blood supply from the low uterine segment when CI site is close to the internal cervical Os.
Fetal short time variation during labor: a non-invasive alternative to fetal scalp pH measurements?
Authors: Schiermeier Sven , Reinhard Joscha , Hatzmann Hendrike , Zimmermann Ralf C. , Westhof Gregor
Published: June 2009

Objective: To determine whether short time variation (STV) of fetal heart beat correlates with scalp pH measurements during labor.

Patients and methods: From 1279 deliveries, 197 women had at least one fetal scalp pH measurement. Using the CTG-Player®, STVs were calculated from the electronically saved cardiotocography (CTG) traces and related to the fetal scalp pH measurements.

Results: There was no correlation between STV and fetal scalp pH measurements (r=−0.0592).

Conclusions: Fetal STV is an important parameter with high sensitivity for antenatal fetal acidosis. This study shows that STV calculations do not correlate with fetal scalp pH measurements during labor, hence are not helpful in identifying fetal acidosis.
Inappropriate use of vancomycin for preventing perinatal group B streptococcal (GBS) disease in laboring patients
Authors: Peláez Linda M. , Gelber Shari E. , Fox Nathan S. , Chasen Stephen T.
Published: June 2009

Objective: The 2002 CDC guidelines for the prevention of perinatal group B streptococcus (GBS) stipulate that vancomycin is reserved for penicillin-allergic women at high risk for beta-lactam anaphylaxis with resistance to clindamycin or erythromycin. Our objective was to evaluate practitioner adherence to these guidelines.

Methods: This is a retrospective chart review of patients admitted to labor and delivery who received vancomycin for GBS prophylaxis from January 1st, 2005 to June 1st, 2007. Identification and documentation of allergic reactions to beta lactams and performance of GBS sensitivities at the time of screening were recorded.

Results: Eighty-seven patients reporting a penicillin allergy received vancomycin during labor. In 71 patients screened at 35–37 weeks, sensitivities were not performed for 55 patients, of which 10 reported an anaphylactic-like reaction to penicillin. Of 15 patients who had sensitivities performed at the time of screening and were resistant to clindamycin and/or erythromycin, only two patients, however, described an anaphylactic-like reaction to penicillin. Fourteen patients received vancomycin due to an unknown GBS status at <35 weeks of gestation and only three patients from this group reported an anaphylactic-like reaction to penicillin. There were deviations from the CDC protocol in 82 (94%) of 87 patients who received intrapartum vancomycin there were deviations in the CDC protocol.

Conclusion: Most patients receiving intrapartum vancomycin for perinatal GBS prophylaxis either did not have a culture with sensitivities performed at the time of GBS screening due to a history of anaphylactic-like reactions to penicillin or received vancomycin for a mild or unknown allergy. Physician adherence to the CDC guidelines with regards to the use of vancomycin is far from optimal.
Arylsulphatase A activity and sulphatide concentration in placenta, membranes and cord after delivery
Authors: Indraccolo Ugo , Traini Enea , Baldoni Emilia , Indraccolo Salvatore Renato , Vitaioli Lucia
Published: June 2009

Aim: We evaluated variations in behavior of arylsulphatase A activity (an enzyme that catabolizes sulphatides) and of sulphatide concentration in the placenta, cord and membranes of healthy gravidas at term pregnancy, following spontaneous birth.

Methods: We extracted and biochemically determined arylsulphatase A and sulphatide concentration in placenta, cord and membranes (far from and close to internal uterine os) in 14 patients.

Results: Activity of arylsulphatase A decreased in the cord, in membranes far from the internal uterine os, in membranes close to the internal uterine os and in the placenta. Sulphatide concentration was minimal in the cord and maximal in placenta, with intermediate values in the membranes. No correlation was found between arylsulphatase A activity and sulphatide concentration, nor among arylsulphatase A activities, nor among sulphatide concentrations among the different tissues. It seems that multiparity may increase and the duration of active labor may decrease arylsulphatase A activity in membranes far from the internal uterine os, while active labor duration does not appear to have any implication on sulphatide concentration in membranes close to the internal uterine os.

Conclusions: Arylsulphatase A activities and sulphatide concentrations in fetal adnexa show significant differences.
Prenatal diagnosis and postnatal management of meconium peritonitis
Authors: Saleh Nadia , Geipel Annegret , Gembruch Ulrich , Heep Axel , Heydweiller Andreas , Bartmann Peter , Franz Axel R. , Müller Andreas
Published: June 2009

Background:Meconium peritonitis (MP) is a rare prenatal condition that leads to substantial neonatal morbidity and mortality.

Patients and methods:All patients between 1998 and 2006 referred for prenatal diagnosis were retrospectively analyzed for diagnosis of MP. Prenatal ultrasound findings were compared with postnatal etiology, intraoperative findings, and postnatal outcome of the patients.

Results:Antenatal MP was diagnosed in 14 fetuses between 18 and 38 weeks' gestation. The prenatal diagnosis of MP was confirmed by clinical and radiological findings in 8 (62%) of 13 infants born alive. All patients were delivered preterm between 33 and 36 weeks' gestation by cesarean section. Urgent neonatal surgery for treatment of bowel obstruction was required in all eight infants. Prenatal ultrasound diagnosis of bowel dilatation was the only variable found to be associated with the need for subsequent surgical intervention (P=0.02).

Conclusions:Clinical outcome of MP diagnosed antenatally can be either mild or severe form. The underlying cause of severe MP is heterogeneous and neonatal surgery was always required.
Corticocortical Interactions between and within Three Cortical Auditory Areas Specialized for Time-Domain Signal Processing
Authors: Tang Jie , Suga Nobuo
Published: June 2009

In auditory cortex of the mustached bat, the FF (F means frequency modulation), dorsal fringe (DF), and ventral fringe (VF) areas consist of “combination-sensitive” neurons tuned to the pair of an emitted biosonar pulse and its echo with a specific delay (best delay: BD). The DF and VF areas are hierarchically at a higher level than the FF area. Focal electric stimulation of the FF area evokes “centrifugal” BD shifts of DF neurons, i.e., shifts away from the BD of the stimulated FF neurons, whereas stimulation of the DF neurons evokes “centripetal” BD shifts of FF neurons, i.e., shifts toward the BD of the stimulated DF neurons. In our current studies, we found that the feedforward projection from FF neurons evokes centrifugal BD shifts of VF neurons, that the feedback projection from VF neurons evokes centripetal BD shifts of FF neurons, that the contralateral projection from DF neurons evokes centripetal BD shifts of DF neurons, and that the centripetal BD shifts evoked by the DF and VF neurons are 2.5 times larger than the centrifugal BD shifts evoked by the FF neurons. The centrifugal BD shifts shape the selective neural representation of a specific target distance, whereas the centripetal BD shifts expand the representation of the selected specific target distance to focus on the processing of the target information at a specific distance. The centrifugal and centripetal BD shifts evoked by the feedforward and feedback projections promote finer analysis of a target at shorter distances.
l-Dopa Modulates Functional Connectivity in Striatal Cognitive and Motor Networks: A Double-Blind Placebo-Controlled Study
Authors: Kelly Clare , de Zubicaray Greig , Di Martino Adriana , Copland David A. , Reiss Philip T. , Klein Donald F. , Castellanos F. Xavier , Milham Michael P. , McMahon Katie
Published: June 2009

Functional connectivity (FC) analyses of resting-state fMRI data allow for the mapping of large-scale functional networks, and provide a novel means of examining the impact of dopaminergic challenge. Here, using a double-blind, placebo-controlled design, we examined the effect ofl-dopa, a dopamine precursor, on striatal resting-state FC in 19 healthy young adults. We examined the FC of 6 striatal regions of interest (ROIs) previously shown to elicit networks known to be associated with motivational, cognitive and motor subdivisions of the caudate and putamen (Di Martino et al., 2008). In addition to replicating the previously demonstrated patterns of striatal FC, we observed robust effects ofl-dopa. Specifically,l-dopa increased FC in motor pathways connecting the putamen ROIs with the cerebellum and brainstem. Althoughl-dopa also increased FC between the inferior ventral striatum and ventrolateral prefrontal cortex, it disrupted ventral striatal and dorsal caudate FC with the default mode network. These alterations in FC are consistent with studies that have demonstrated dopaminergic modulation of cognitive and motor striatal networks in healthy participants. Recent studies have demonstrated altered resting state FC in several conditions believed to be characterized by abnormal dopaminergic neurotransmission. Our findings suggest that the application of similar experimental pharmacological manipulations in such populations may further our understanding of the role of dopaminergic neurotransmission in those conditions.
Lateral Intraparietal Cortex and Reinforcement Learning during a Mixed-Strategy Game
Authors: Seo Hyojung , Barraclough Dominic J. , Lee Daeyeol
Published: June 2009

Activity of the neurons in the lateral intraparietal cortex (LIP) displays a mixture of sensory, motor, and memory signals. Moreover, they often encode signals reflecting the accumulation of sensory evidence that certain eye movements might lead to a desirable outcome. However, when the environment changes dynamically, animals are also required to combine the information about its previously chosen actions and their outcomes appropriately to update continually the desirabilities of alternative actions. Here, we investigated whether LIP neurons encoded signals necessary to update an animal's decision-making strategies adaptively during a computer-simulated matching-pennies game. Using a reinforcement learning algorithm, we estimated the value functions that best predicted the animal's choices on a trial-by-trial basis. We found that, immediately before the animal revealed its choice, ∼18% of LIP neurons changed their activity according to the difference in the value functions for the two targets. In addition, a somewhat higher fraction of LIP neurons displayed signals related to the sum of the value functions, which might correspond to the state value function or an average rate of reward used as a reference point. Similar to the neurons in the prefrontal cortex, many LIP neurons also encoded the signals related to the animal's previous choices. Thus, the posterior parietal cortex might be a part of the network that provides the substrate for forming appropriate associations between actions and outcomes.
Learning from Errors: Error-Related Neural Activity Predicts Improvements in Future Inhibitory Control Performance
Authors: Hester Robert , Madeley Janelle , Murphy Kevin , Mattingley Jason B.
Published: June 2009

Failure to adapt performance following an error is a debilitating symptom of many neurological and psychiatric conditions. Healthy individuals readily adapt their behavior in response to an error, an ability thought to be subserved by the posterior medial frontal cortex (pMFC). However, it remains unclear how humans adaptively alter cognitive control behavior when they reencounter situations that were previously failed minutes or days ago. Using functional magnetic resonance imaging, we examined neural activity during a Go/No-go response inhibition task that provided the opportunity for participants to learn from their errors. When they failed to inhibit their response, they were shown the same target stimulus during the next No-go trial, which itself could occur up to 20 trials after its initial presentation. Activity within the pMFC was significantly greater for initial errors that were subsequently corrected than for errors that were repeated later in the display sequence. Moreover, pMFC activity during errors predicted future responses despite a sizeable interval (on average 12 trials) between an error and the next No-go stimulus. Our results indicate that changes in cognitive control performance can be predicted using error-related activity. The increased likelihood of adaptive changes occurring during periods of recent success is consistent with models of error-related activity that argue for the influence of outcome expectancy (Holroyd and Coles, 2002; Brown and Braver, 2005). The findings may also help to explain the diminished error-related neural activity in such clinical conditions as schizophrenia, as well as the propensity for perseverative behavior in these clinical groups.
Opposing Influences of Affective State Valence on Visual Cortical Encoding
Authors: Schmitz Taylor W. , De Rosa Eve , Anderson Adam K.
Published: June 2009

Positive and negative emotional states are thought to have originated from fundamentally opposing approach and avoidance behaviors. Furthermore, affective valence has been hypothesized to exert opposing biases in cognitive control. Here we examined with functional magnetic resonance imaging whether the opposing influences of positive and negative states extend to perceptual encoding in the visual cortices. Based on prior behavioral research, we hypothesized that positive states would broaden and negative states would narrow visual field of view (FOV). Positive, neutral, and negative states were induced on alternating blocks. To index FOV, observers then viewed brief presentations (300 ms) of face/place concentric center/surround stimuli on interleaved blocks. Central faces were attended, rendering the place surrounds unattended. As face and place information was presented at different visual eccentricities, our physiological metric of FOV was a valence-dependent modulation of place processing in the parahippocampal place area (PPA). Consistent with our hypotheses, positive affective states increased and negative states decreased PPA response to novel places as well as adaptation to repeated places. Individual differences in self-reported positive and negative affect correlated inversely with PPA encoding of peripheral places, as well as with activation in the mesocortical prefrontal cortex and amygdala. Psychophysiological interaction analyses further demonstrated that valence-dependent responses in the PPA arose from opponent coupling with extrafoveal regions of the primary visual cortex during positive and negative states. These findings collectively suggest that affective valence differentially biases gating of early visual inputs, fundamentally altering the scope of perceptual encoding.
Trasibulo y el fracaso de la reconstrucción imperial ateniense en la guerra de Corinto
Authors: Fornis César
Published: June 2009

En los últimos años de la guerra de Corinto (395386 a. C.) los atenienses emprendieron, bajo el patrocinio político de Trasibulo de Estiria, la reconstrucción de la arche del siglo V. En el presente trabajo analizamos la naturaleza, el alcance y las consecuencias, internas y externas, de este intento de renacimiento imperial que murió con la paz del Rey.
Verwehrte Ehre: Zur Wertigkeit des triumphus in monte Albano
Authors: Rosenberger Veit
Published: June 2009

Insgesamt läßt sich ein deutlicher qualitativer Unterschied zwischen dem regulären Triumph in Rom und dem triumphus in monte Albano aufzeigen. Nach der Ablehnung eines Triumphes in Rom war der Triumph auf dem Albaner Berg stets nur die zweite Wahl. Die Orte in Rom, an denen die Route des Triumphzuges vorbeiführte, waren ungleich stärker mit Bedeutung aufgeladen als der Albaner Berg, auch der Kreis der Adressaten war in Rom deutlich größer als in dem eine Tagesreise entfernten Heiligtum, so daß der Triumph in Rom wesentlich höheres Prestige einbrachte.
Politische Öffentlichkeit statt Mitbestimmung? Zur Bedeutung der contiones in der mittleren und späten römischen Republik
Authors: Tiersch Claudia
Published: June 2009

Die Untersuchung befaßt sich mit dem Volksversammlungstyp der contiones als entscheidender kommunikativer Schnittstelle zwischen Volk und Senat in der Zeit der römischen Republik. Durch eine Analyse kommunikativer und performativer Mechanismen, aber auch der hier thematisierten Gegenstandsbereiche wird gezeigt, warum es nobilitären Rednern innerhalb der mittleren Republik meist gelang, die Akzeptanz der Bürgerschaft für die von ihnen formulierten politischen Ziele zu gewinnen. Hierbei gelang die Integration der Bürger trotz einer zutiefst hierarchischen Kommunikationsstruktur, denn die aristokratischen Redner vermochten ihre herausgehobenen Geltungsansprüche durch die Verheißung patronalen Leistungsaustauschs an geltende Sozialbeziehungen anzuknüpfen und dadurch für die Zuhörer mit sozialem Sinn zu erfüllen. Allerdings verdeutlichte die wachsende Gewalt innerhalb der contiones der späten Republik die institutionellen Grenzen dieses Versammlungstyps. Dieser war nicht mehr in der Lage, die massiven Interessengegensätze jener Jahrzehnte kommunikativ zu bewältigen. Insofern wird die Krise der späten römischen Republik auch als Störung der Kommunikationsbeziehungen zwischen Ober- und Unterschichten faßbar.
Iscrizioni nord-umbre del bellum sociale nella Valle di Ospitale: prime indicazioni
Authors: Zavaroni Adolfo , Sani Giancarlo
Published: June 2009

Riassunto

Nella Valle di Ospitale (Alto Appennino Modenese) sono recentemente tornate alla luce, nei siti di La Sega e La Tana, numerose iscrizioni rupestri scritte durante il bellum sociale (90–89 a. C.) da militi ribellatisi a Roma. Essi si definiscono Umbri, ma il loro dialetto contiene varie particolarità che inducono a distinguerlo dall′umbro delle Tavole Iguvine. L′alfabeto contiene alcune lettere speciali, ma si caratterizza soprattutto per il frequente uso di legature. La maggior parte delle iscrizioni è costituita da esortazioni a rivoltarsi contro Roma ed a formare una Lega Umbra. Alcune scritte hanno un contenuto erotico; altre sono illuminanti per ricostruire il pantheon di questi rivoltosi. Qui si presenta una selezione delle iscrizioni più facilmente leggibili.
Zwischen Emotion und Normerfüllung – Verwandtschaftliche Beziehungen in den Schriften spätantiker gallischer Autoren
Authors: Zittel Diemut
Published: June 2009

Ausonius, der Rhetor und Prinzenerzieher, setzte im 4. Jh. seinen Verwandten in den Parentalia ein Denkmal. Insbesondere gilt dies für seinen avunculus Arborius, zu dem er eine enge affektive Beziehung hatte. Im Unterschied zur Zeit der römischen Republik erfüllt diese Beziehung jedoch keine konkrete und normative Rollenerwartung – der avunculus in seiner Funktion als Beschützer seiner Nichten und Neffen und als Gegengewicht zum pater und seiner patria potestas. Denn Ausonius kann seine Beziehung zu Arborius nur durch Vergleiche mit Vater und Mutter beschreiben. Auch für andere Verwandte sind bei Ausonius keine klar erwartbaren Verhaltensmuster nachzuweisen. Diesen Mangel versucht Ausonius durch eine Betonung der affektiven Bindungen auszugleichen. Der Versuch, den Kreis auch der entfernteren Verwandten auf diese Weise enger zu schließen, kann auch als Anstrengung gewertet werden, der Fragilität der Verwandtschaftsbeziehungen, die durch das Verblassen konkreter Rollenerwartungen entsteht, etwas entgegen zu setzen. In dieser ‚Emotionalisierung‘ der verwandtschaftlichen Beziehungen spiegeln sich auch die politischen Veränderungen des Prinzipats wider. Wenn den verwandtschaftlichen Beziehungen politische Funktionen verloren gehen (wie den adligen patres als Erzwingungstab der Republik), so schwinden auch die damit verknüpften Verhaltensmodelle. Es entsteht Raum für verwandtschaftliche Beziehungen, für die Affektivität nicht mehr kontingent, sondern konstitutiv wird.

Die gallische Aristokratie versuchte auch nach dem Zusammenbruch des römischen Imperiums in Gallien im 5. Jh. ‚ihre Welt‘ zu retten, indem sie zum Beispiel die klassischen Bildungsgüter pflegte, auch wenn sie längst christlich geworden war. Ganz besonders aber auch indem sie verwandtschaftliche Beziehungen intensiv pflegte. Sidonius′ Briefe an seine patrui bezeugen, daß er sehr enge Beziehungen zu diesen unterhielt, daß diese sich jedoch im wesentlichen im Rahmen des antiken amicitia-Konzeptes beschreiben lassen. Den patrui wird augenscheinlich kein spezifisches Verhalten geschuldet. So stellen Familie und Verwandtschaft auch in der Spätantike einen außerordentlich wichtigen Bezugsrahmen dar, ohne daß sich jedoch neue allgemeinverbindliche und konkrete Verhaltensmodelle für einzelne Verwandte entwickelt hätten.
Rapid rates of sperm DNA damage after activation in tench (Tinca tinca: Teleostei, Cyprinidae) measured using a sperm chromatin dispersion test
Authors: López-Fernández Carmen , Gage Matthew J G , Arroyo Francisca , Gosálbez Altea , Larrán Ana M , Fernández José L , Gosálvez Jaime
Published: June 2009

Spermatozoal haplotypic DNA is prone to damage, leading to male fertility problems. So far, the assessment of sperm DNA breakage has been challenging because protamines render the nuclear chromatin highly compacted. Here, we report the application of a new test to quantify DNA fragmentation in spermatozoa of an externally fertilizing teleost fish. The sperm chromatin dispersion (SCD) test uses a species-specific lysing solution to generate controlled protein depletion that, followed by DNA-specific fluorescent labelling, allows an easy morphological discrimination between nuclei affected by DNA damage. Using tench (Tinca tinca) as our model, we first trialled the test against established, but more technically demanding, assays employingin situnick translation (ISNT) and the comet assay. The SCD test showed high concordance with ISNT, comet assay measures and a chromatin-swelling test, confirming the application of this straightforward SCD technique to various aspects of reproductive biology. Second, we examined between-male variation in DNA damage, and measured changes through time following spermatozoal activation. Between-male variation in the basal levels of average DNA damage ranged from 0 to 20% of sperm showing damage, and all showed increases in DNA fragmentation through time (0–60 min). The rates of DNA damage increase are the fastest so far recorded in sperm for a living organism, and may relate to the external fertilization mode. Our findings have relevance for broodstock selection and optimizing IVF protocols routinely used in modern aquaculture.
Effect of Postmanufacturing Processing and Shipping of Luteinizing Hormone Releasing Hormone Analog on Induced Ovulation for Production of Channel Catfish Female × Blue Catfish Male Hybrid Fry
Authors: Kristanto Anang H , Umali Gloria , Beam Renee , Dunham Rex A
Published: June 2009

The potential effects of postmanufacturing processing and shipping of luteinizing hormone releasing hormone analog (LHRH-a) on induced ovulation for the production of hybrids of female channel catfish Ictalurus punctatus × male blue catfish I. furcatus were evaluated. There were no differences in efficacy regarding postmanufacturing bottling. Hand-weighed LHRH-a gave results similar to those of LHRH-a reconstituted in water, aliquoted, and relyophilized. Shipping without dry ice reduced the number of fry per kilogram of female body weight by 51–87% . Theoretically, dry ice is not necessary when shipping powdered LHRH-a, but these results indicate that to ensure efficacy (as indicated by total fry production) shipping LHRH-a on dry ice would be a best management practice. Hybrid embryos were successfully produced, and LHRH-a injections are a viable alternative to carp pituitary extract injections for producing hybrid catfish embryos.
Survival and Passage of Ingested New Zealand Mudsnails through the Intestinal Tract of Rainbow Trout
Authors: Bruce R Louise , Moffitt Christine M , Dennis Brian
Published: June 2009

We conducted laboratory trials to determine the transit time and survival of New Zealand mudsnails Potamopyrgus antipodarum in the gastrointestinal tract of rainbow trout Oncorhynchus mykiss. To assess the rate of snail passage, we force-fed groups of fish a known quantity of snails and then held them in tanks. At selected intervals we removed individual fish from the test tanks and recorded the number of snails, their condition (live or dead), and their location in the gastrointestinal tract (stomach, anterior intestine, and posterior intestine). Feces were removed from tanks and examined for live snails. We repeated evaluations of passage rate and snail survival to determine the effects of varying the number of snails ingested, fish size, snail size, and feeding a commercial diet to fish after snail ingestion. We plotted and modeled gut evacuation using a stochastic model for ordinal data to consider each test variable. Snail passage rates were faster in fish that were fed smaller snails. Surprisingly, fish fed snails and then administered rations of commercial fish feed retained the snails longer in their stomach than did fish that were not administered fish feeds after being fed snails. Increased retention time of snails in the stomach decreased the probability of snail survival when voided in fecal material. Snails that passed through the gastrointestinal tract within 12–24 h of ingestion were often recovered live in fecal samples. However, no live snails were recovered from the posterior intestine or fecal material collected 24 h after ingestion. Using our results we propose potential management options that could reduce the risks of introducing live snails into new locations when stocking fish from infested hatcheries.
A fungus among us: broad patterns of endophyte distribution in the grasses
Authors: Rudgers Jennifer A. , Afkhami Michelle E. , Rúa Megan A. , Davitt Andrew J. , Hammer Samantha , Huguet Valérie M.
Published: June 2009

Plant‐associated microbes have been increasingly recognized for influencing host populations, plant communities, and even herbivores and predators. Thus, understanding factors that affect the distribution and abundance of microbial symbioses may be important for predicting the ecological dynamics of communities. Using endophytic fungi–grass symbioses, we explored how intrinsic traits of the symbiosis, specifically transmission mode, may influence symbiont frequencies in host populations. Combining published literature with new field surveys, we comparedEpichloëendophytes, which had mixed horizontal and vertical transmission, withNeotyphodiumendophytes, which were exclusively vertically transmitted from host plants to seeds. Exclusively vertical transmission should select against pathogenicity because symbionts depend entirely on hosts for reproduction. Across 118 host species, we found thatNeotyphodiumhosts had 40–130% higher symbiont frequencies thanEpichloëhosts. In field surveys, endophyte frequency was positively correlated with the local density of hosts, but only forEpichloë, suggesting that contagiously spreadEpichloëmay attain higher frequencies when hosts are more abundant.Epichloëendophytes were also more likely thanNeotyphodiumto have imperfect vertical transmission; thus, hosts may reduce the transmission of more pathogenic symbionts to seeds. Results are consistent with the conclusion that the evolutionary transition to exclusively vertical transmission can alter patterns of symbiont frequency in nature.
Survival costs associated with wood frog breeding migrations: effects of timber harvest and drought
Authors: Rittenhouse Tracy A. G. , Semlitsch Raymond D. , Thompson Frank R.
Published: June 2009

Migration presents a trade‐off for individuals between the potential fitness benefits of reaching high‐quality habitat vs. the potential costs of migration. Within an information‐theoretic framework, we examined the costs of migration for adult wood frogs (Rana sylvatica) in response to timber harvest and annual weather conditions using Cox proportional‐hazard estimates of survival. In 2004 prior to timber harvest, survival did not differ between the inside (0.75, SE = 0.078) and outside (0.73, SE = 0.235) of the circular timber harvest arrays (each 164 m radius). Following timber harvest, survival inside arrays in both 2005 and 2006 (0.22, SE = 0.065; 0.42, SE = 0.139) was lower than survival outside of the arrays and prior to harvest. Sources of mortality included predation in all years and desiccation in the drought year of 2005. The most‐supported models for explaining both predation and desiccation risks reflected behaviors as opposed to timber harvest or weather conditions. Both predation and desiccation risks increased when frogs made frequent movements or were located near breeding ponds. Optimal behaviors for reducing predation and desiccation risks were the same before and after timber harvest; however, the survival consequences for not adopting these behaviors were more severe following harvest. Our results provide empirical evidence for (1) the ecological pressures that influence migratory behavior and (2) differential survival in relation to migratory behavior which reveals why frogs move relatively long distances away from breeding sites.
Aboveground overyielding in grassland mixtures is associated with reduced biomass partitioning to belowground organs
Authors: Bessler Holger , Temperton Vicky M. , Roscher Christiane , Buchmann Nina , Schmid Bernhard , Schulze Ernst-Detlef , Weisser Wolfgang W. , Engels Christof
Published: June 2009

We investigated effects of plant species richness in experimental grassland plots on annual above‐ and belowground biomass production estimated from repeated harvests and ingrowth cores, respectively. Aboveground and total biomass production increased with increasing plant species richness while belowground production remained constant. Root to shoot biomass production ratios (R/S) in mixtures were lower than expected from monoculture performance of the species present in the mixtures, showing that interactions among species led to reduced biomass partitioning to belowground organs. This change in partitioning to belowground organs was not confined to mixtures with legumes, but also measured in mixtures without legumes, and correlated with aboveground overyielding in mixtures. It is suggested that species‐rich communities invest less in belowground biomass than do monocultures to extract soil resources, thus leading to increased investment into aboveground organs and overyielding.
Longitudinal analysis of Plantago: Age‐by‐environment interactions reveal aging
Authors: Roach Deborah A. , Ridley Caroline E. , Dudycha Jeffry L.
Published: June 2009

We know very little about aging (senescence) in natural populations, and even less about plant aging. Demographic aging is identified by an increasing rate of mortality following reproductive maturity. In natural populations, quantifying aging is often confounded because changes in mortality may be influenced by both short‐ and long‐term environmental fluctuations as well as age‐dependent changes in performance. Plants can be easily marked and monitored longitudinally in natural populations yet the age‐dependent dynamics of mortality are not known. This study was designed to determine whether a plant species, Plantago lanceolata, shows demographic aging in its natural environment. A large, multiple‐cohort design was used to separate age‐independent and age‐dependent processes. Seven years of results show environmental influences on mortality as evidenced by synchronous changes in mortality across four cohorts over time. Age‐dependent mortality was found through an age‐by‐environment interaction when the oldest cohorts had significantly higher mortality relative to the younger cohorts during times of stress. Neither size nor quantity of reproduction could explain this variation in mortality across cohorts. These results demonstrate demographic senescence in a natural population of plants.
Floral morphology mediates temporal variation in the mating system of a self‐compatible plant
Authors: Eckert Christopher G. , Ozimec Barbara , Herlihy Christopher R. , Griffin Celine A. , Routley Matthew B.
Published: June 2009

The mating system of self‐compatible plants may fluctuate between years in response to ecological factors that cause variation in the deposition of self pollen vs. outcross pollen on stigmas. Such temporal variation may have significant ecological and evolutionary consequences, but it has rarely been studied, and the mechanisms that mediate temporal variation have almost never been investigated. We tested for variation in the proportion of seeds self‐fertilized (s) between two years within 19 populations of the short‐lived herbAquilegia canadensis. Selfing varied widely among populations (range ins= 0.17–1.00, means= 0.82) but was inconsistent across years, indicating significant temporal variation. Three populations exhibited especially wide swings in the mating system between years. Meansdid not decrease with increasing population size (N), nor was the fluctuation insassociated with meanNor the change inN. As expected,sdeclined with increasing separation between anthers and stigmas within flowers (herkogamy), andsfluctuated to a greater extent in populations with more herkogamous flowers. Self‐compatible plants can experience wide temporal variation in self‐fertilization, and floral traits such as herkogamy may mediate temporal variation by forestalling self‐pollination and thus allowing outcrossing during periods when pollinators are frequent.
Food abundance does not determine bird use of early‐successional habitat
Authors: Champlin Tracey B. , Kilgo John C. , Moorman Christopher E.
Published: June 2009

Few attempts have been made to experimentally address the extent to which temporal or spatial variation in food availability influences avian habitat use. We used an experimental approach to investigate whether bird use differed between treated (arthropods reduced through insecticide application) and control (untreated) forest canopy gaps within a bottomland hardwood forest in the Upper Coastal Plain of South Carolina, USA. Gaps were two‐ to three‐year‐old group selection timber harvest openings of three sizes (0.13, 0.26, and 0.50 ha). Our study was conducted during four bird use periods (spring migration, breeding, post‐breeding, and fall migration) in 2002 and 2003. Arthropods were reduced in treated gaps by 68% in 2002 and 73% in 2003. We used mist‐netting captures and foraging attack rates to assess the influence of arthropod abundance on avian habitat use. Evidence that birds responded to arthropod abundance was limited and inconsistent. In 2002, we generally captured more birds in treated gaps of the smallest size (0.13 ha) and fewer birds in treated gaps of the larger sizes. In 2003, we recorded few differences in the number of captures in treated and control gaps. Foraging attack rates generally were lower in treated than in control gaps, indicating that birds were able to adapt to the reduced food availability and remain in treated gaps. We conclude that arthropod abundance was not a proximate factor controlling whether forest birds used our gaps. The abundance of food resources may not be as important in determining avian habitat selection as previous research has indicated, at least for passerines in temperate subtropical regions.
Metapopulation responses to patch connectivity and quality are masked by successional habitat dynamics
Authors: Hodgson Jenny A. , Moilanen Atte , Thomas Chris D.
Published: June 2009

Many species have to track changes in the spatial distribution of suitable habitat from generation to generation. Understanding the dynamics of such species will likely require spatially explicit models, and patch‐based metapopulation models are potentially appropriate. However, relatively little attention has been paid to developing metapopulation models that include habitat dynamics, and very little to testing the predictions of these models. We tested three predictions from theory about the differences between dynamic habitat metapopulations and their static counterparts using long‐term survey data from two metapopulations of the butterfly Plebejus argus. As predicted, we showed first that the metapopulation inhabiting dynamic habitat had a lower level of habitat occupancy, which could not be accounted for by other differences between the metapopulations. Secondly, we found that patch occupancy did not significantly increase with increasing patch connectivity in dynamic habitat, whereas there was a strong positive connectivity–occupancy relationship in static habitat. Thirdly, we found no significant relationship between patch occupancy and patch quality in dynamic habitat, whereas there was a strong, positive quality–occupancy relationship in static habitat. Modeling confirmed that the differences in mean patch occupancy and connectivity–occupancy slope could arise without changing the species' metapopulation parameters—importantly, without changing the dependence of colonization upon connectivity. We found that, for a range of landscape scenarios, successional simulations always produced a lower connectivity–occupancy slope than comparable simulations with static patches, whether compared like‐for‐like or controlling for mean occupancy. We conclude that landscape‐scale studies may often underestimate the importance of connectivity for species occurrence and persistence because habitat turnover can obscure the connectivity–occupancy relationship in commonly available snapshot data.
Dispersal in a Neotropical tree, Virola flexuosa (Myristicaceae): Does hunting of large vertebrates limit seed removal?
Authors: Holbrook K. M. , Loiselle B. A.
Published: June 2009

To understand how different frugivores impact dispersal, we studied the assemblage that feed on Virola flexuosa over a two‐year period at two sites differing in hunting pressure in Ecuador. We focus on disperser effectiveness and test the hypothesis that seed removal, influenced by differential visits of large‐bodied frugivores, will differ between hunted and non‐hunted sites. All visiting frugivores were identified, and fruit handling behavior and seed removal rates quantified. Seed traps were placed under fruiting trees to estimate crop size and fruit removal. Seventeen bird and three primate species were recorded foraging in V. flexuosa trees. Toucans and primates were the most important dispersers comprising nearly 85% of visits with six toucan species recorded in 74% of visits. A proportionately larger number of seeds were removed from fruiting trees at a non‐hunted site (89.4%) than a hunted site (66.8%). In addition, there were significantly more frugivore visits at the non‐hunted than the hunted site. The differences in the frugivore assemblage and the number of seeds dispersed from individual trees between two structurally similar forest sites suggest dispersal limitation resulting from a decline in frugivores.
Watershed discharge modulates relationships between landscape components and nutrient ratios in stream seston
Authors: Frost Paul C. , Kinsman Lauren E. , Johnston Carol A. , Larson James H.
Published: June 2009

In order to understand the environmental controls of the elemental composition of suspended particles in streams and rivers, we examined relationships between the stoichiometry of suspended particles and catchment characteristics (e.g., topography and land cover) under contrasting hydrological conditions in streams from the Upper Peninsula of Michigan, USA. Particulate C:N, N:P, and C:P ratios varied considerably among streams on each of 10 separate sampling dates and within most streams through time. When averaged across the study period by stream, particulate C:N:P ratios were strongly related to several catchment properties. For example, particulate C:P and N:P ratios were negatively related to the percentage of catchment used for agriculture but positively related to the percentage of catchment found as wetlands. These relationships reflected, in part, variable concentrations of mineral particles, which were strongly related to stream length, agriculture, and upstream lake area. In addition, the strength of the relationships between particulate elemental composition and catchment properties changed depending upon hydrologic condition of the Ontonagon watershed. For example, periods of wetness, as indicated by high river discharge, were found to increase the strength of seston C:N ratio–percentage of wetlands relationships but to reduce the strength of seston C:P ratios–percentage of wetlands relationships. Our results thus demonstrate that the balance of elements fluxing through forested streams is strongly affected by catchment properties but that these effects are sensitive to watershed discharge. At times of high discharge, there are strong connections to catchment sources while in‐stream processes appear to predominate at time of low discharge.