Ammonia concentrations in water can affect the severity of Flavobacterium columnare infections in fish. Two trials lasting 7 d each were conducted to determine the effect of a single immersion flush ...treatment of total ammonia nitrogen (TAN; 15 mg/L) on the survival of channel catfish Ictalurus punctatus infected with F. columnare; the chemical was added while the water flowed continuously through the tanks. Both trials consisted of four treatments: (1) no ammonia exposure and no bacterial challenge (control), (2) ammonia exposure only, (3) bacterial challenge only, and (4) both ammonia exposure and bacterial challenge. Two hours after exposure to ammonia, the highest un‐ionized ammonia level was 0.43 mg/L. The percent un‐ionized ammonia is based on TAN, temperature, and pH. Caudal fins from three fish in each treatment were sampled at 24 h posttreatment to be analyzed by quantitative real‐time polymerase chain reaction (qPCR). No significant difference in survival (mean ± SE) was noted between the channel catfish in treatment 1 (95.2 ± 1.2%) and those in treatment 2 (95.6 ± 1.0%); however, survival in both treatments 1 and 2 differed significantly from that in treatments 3 (8.5 ± 4.5%) and 4 (41.8 ± 12.7%). Treatment 4 catfish had significantly higher survival than treatment 3 catfish. Quantitative PCR data showed that treatment 4 fish had significantly less F. columnare (7.6 × 105) than did treatment 3 fish (1.2 × 107), and treatment 2 fish (8.5 × 103) had significantly less bacteria than did treatment 1 fish (6.9 × 104), indicating that ammonia limited the F. columnare infection. The highest mean concentration of the bacteria (3.9 × 107) was found on moribund fish. The ammonia concentrations tested did not negatively influence fish survival but interfered with the infection process. An in vitro assay was also conducted to evaluate the direct effects of ammonia on F. columnare.
Received September 15, 2010; accepted May 7, 2011
The hexanuclear cages Mn
6
O
2
(R-sao)
6
L
2
(EtOH)
x
(H
2
O)
y
"Mn
6
" behave as single-molecule magnets (SMMs) below a characteristic blocking temperature. As with Mn
12
O
12
(O
2
CR)
16
(H
2
O)
4
... "Mn
12
" the electronic absorption spectra are rather featureless, yielding little information on the electronic structure of the magnetic ions. Low temperature Magnetic Circular Dichroism (MCD) spectra afford greater resolution of the optical transitions and also probe the magnetic properties of the system. Both the ground state spin and blocking temperature of the Mn
6
cages are determined by subtle structural perturbations of a generic Mn
6
O
2
core. Absorbance and MCD spectra are reported for Mn
6
O
2
(Et-sao)
6
{O
2
CPh(Me)
2
}
2
(EtOH)
6
(
1
), Mn
6
O
2
(Et-sao)
6
{O
2
CPh}
2
(EtOH)
4
(H
2
O)
2
(
2
), Mn
6
O
2
(sao)
6
{O
2
CPh}
2
(EtOH)
4
·EtOH (
3
) and the trinuclear precursor Mn
3
O(Et-sao)
3
(MeOH)
3
(ClO
4
) (
4
) cast into polymer film. SMM behaviour has previously been observed using magnetic susceptibility measurements on powder and single-crystal samples. The ligand field environment of the magnetic ions is assumed to be similar in (
1
) and (
2
) and their different blocking temperatures are attributed to the magnitude of the effective exchange constant. The MCD spectra of (
1
) and (
2
), in which the ground state spin
S
= 12, show that the ligand field environments of the Mn ions are almost identical and that magnetic hysteresis persists for isolated molecules when crystal packing forces are removed. The subtle structural differences between (
1
) and (
2
) are manifested in the field dependence of the MCD response at different wavelengths that reflect changes in band polarisation. The MCD spectrum of (
3
) contains features not apparent in those of (
1
) and (
2
). These are attributed to 5-coordinate Mn(
iii
), which is unique to (
3
) among the compounds studied. (
3
) has ground state spin
S
= 4, a lower blocking temperature and consequently no observable hysteresis in the MCD down to 1.7 K. Comparison of the MCD spectra of (
1
)-(
3
) to that of (
4
) confirms the integrity of the Mn
6
O
2
core when these materials are cast into polymer film.
MCD spectroscopy shows the SMM behaviour of Mn
6
cages with ground state spin
S
= 12 to persist in isolated molecules.
1 Military Performance Division and 2 Military Nutrition Division, U. S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
Submitted 19 February 2007
; accepted in final form ...13 August 2007
The purpose of this study was to determine the impact of dietary factors and exercise-associated factors on the response of IGF-I and its binding proteins (IGFBPs) during a period of increased physical activity. Twenty-nine men completed a 4-day ( days 1–4 ) baseline period of a controlled energy balanced diet while maintaining their normal physical activity level followed by 7 days ( days 5–11 ) of a 1,000 kcal/day increase in physical activity above their normal activity levels. Two subject groups, one sedentary (Sed, mean O 2peak : 39 ml·kg –1 ·min –1 , n = 7) and one fit (FIT1, mean O 2peak : 56 ml·kg –1 ·min –1 , n = 8) increased energy intake to maintain energy balance throughout the 7-day intervention. In two other fit subject groups (FIT2, n = 7 and FIT3, n = 7), energy intake remained at baseline resulting in a 1,000 kcal/day exercise-induced energy deficit. Of these, FIT2 received an adequate protein diet (0.9 g/kg), and FIT3 received a high-protein diet (1.8 g/kg). For all four groups, IGF-I, IGFBP-3, and the acid labile subunit (ALS) were significantly decreased by day 11 (27 ± 4%, 10 ± 2%, and 19 ± 4%, respectively) and IGFBP-2 significantly increased by 49 ± 21% following day 3 . IGFBP-1 significantly increased only in the two negative energy balance groups, FIT2 (38 ± 6%) and FIT3 (46 ± 8%). Differences in initial fitness level and dietary protein intake did not alter the IGF-I system response to an acute increase in physical activity. Decreases in IGF-I were observed during a moderate increase in physical activity despite maintaining energy balance, suggesting that currently unexplained exercise-associated mechanisms, such as increased energy flux, regulate IGF-I independent of energy deficit.
insulin-like growth factor binding proteins; exercise; nutritional factors
Address for reprint requests and other correspondence: B. C. Nindl, Military Performance Division, U. S. Army Research Institute of Environmental Medicine, Natick, MA 01760 (e-mail: bradley.nindl{at}us.army.mil )
Organizational citizenship behaviors (OCBs) have been the subject of considerable research attention within business organizations. Much less attention has been directed at OCBs within criminal ...justice agencies, and even less research has addressed OCBs within police organizations. The present study uses survey data collected from 829 police officers in India to assess the antecedents of several dimensions of OCBs. Unlike most prior research, we use a path model in an effort to disentangle the direct and indirect effects of organizational justice, job demands and job resources, organizational justice, stress, and work attitudes on OCBs while controlling for officer personal characteristics. Our findings indicate that job satisfaction and organizational commitment are strong predictors of OCBs and that they mediate the effects of job stress, which did not directly influence OCBs. In addition, organizational justice factors exerted inconsistent effects on OCBs. Strategies for increasing the likelihood that officers will engage in OCBs are discussed.
During development, directed cell migration is crucial for achieving proper shape and function of organs. One well-studied example is the embryonic development of the larval tracheal system of ...Drosophila , in which at least four signaling pathways coordinate cell migration to form an elaborate branched network essential for oxygen delivery throughout the larva. FGF signaling is required for guided migration of all tracheal branches, whereas the DPP, EGF receptor, and Wingless/WNT signaling pathways each mediate the formation of specific subsets of branches. Here, we characterize ribbon , which encodes a BTB/POZ-containing protein required for specific tracheal branch migration. In ribbon mutant tracheae, the dorsal trunk fails to form, and ventral branches are stunted; however, directed migrations of the dorsal and visceral branches are largely unaffected. The dorsal trunk also fails to form when FGF or Wingless/WNT signaling is lost, and we show that ribbon functions downstream of, or parallel to, these pathways to promote anterior-posterior migration. Directed cell migration of the salivary gland and dorsal epidermis are also affected in ribbon mutants, suggesting that conserved mechanisms may be employed to orient cell migrations in multiple tissues during development.
Metal–organic frameworks (MOFs) capable of mobility and manipulation are attractive materials for potential applications in targeted drug delivery, catalysis, and small‐scale machines. One way of ...rendering MOFs navigable is incorporating magnetically responsive nanostructures, which usually involve at least two preparation steps: the growth of the magnetic nanomaterial and its incorporation during the synthesis of the MOF crystals. Now, by using optimal combinations of salts and ligands, zeolitic imidazolate framework composite structures with ferrimagnetic behavior can be readily obtained via a one‐step synthetic procedure, that is, without the incorporation of extrinsic magnetic components. The ferrimagnetism of the composite originates from binary oxides of iron and transition metals such as cobalt. This approach exhibits similarities to the natural mineralization of iron oxide species, as is observed in ores and in biomineralization.
Mit der optimalen Kombination von Salzen und Liganden können Zeolith‐Imidazolat‐Gerüst‐Verbundstrukturen mit ferrimagnetischem Verhalten durch eine Einschritt‐Synthese hergestellt werden. Der Ferrimagnetismus stammt dabei von binären Eisen‐ und Übergangsmetalloxiden. Der Ansatz zeigt Ähnlichkeiten zur natürlichen Mineralisierung von Eisenoxidspezies, wie sie in Erzen und Biomineralisierung beobachtet wird.
The efficacy of anatomical magnetic resonance imaging (MRI) in studying the morphological features of various regions of the brain is described, also providing the steps used in the processing and ...studying of the images. The ability to correlate these features with several clinical and psychological measures can help in using anatomical MRI to study childhood psychiatric disorders.
SalM is a short-chain dehydrogenase/reductase enzyme from the marine actinomycete Salinispora tropica that is involved in the biosynthesis of chloroethylmalonyl-CoA, a novel halogenated polyketide ...synthase extender unit of the proteasome inhibitor salinosporamide A. SalM was heterologously overexpressed in Escherichia coli and characterized in vitro for its substrate specificity, kinetics, and reaction profile. A sensitive real-time ¹³C NMR assay was developed to visualize the oxidation of 5-chloro-5-deoxy-D-ribose to 5-chloro-5-deoxy-D-ribono-γ-lactone in an NAD⁺-dependent reaction, followed by spontaneous lactone hydrolysis to 5-chloro-5-deoxy-D-ribonate. Although short-chain dehydrogenase/reductase enzymes are widely regarded as metal-independent, a strong divalent metal cation dependence for Mg²⁺, Ca²⁺, or Mn²⁺ was observed with SalM. Oxidative activity was also measured with the alternative substrates D-erythrose and D-ribose, making SalM the first reported stereospecific non-phosphorylative ribose 1-dehydrogenase.
We investigate the influence of annealing conditions on the physical properties of thin films of poly(3,4‐ethylenedioxythiophene)/poly(styrene sulfonate) (PEDOT/PSS). In particular, we describe how ...annealing temperature, the ambient gas, and choice of dopant affect the conductivity, morphology, and work function of the films. Two specific dopants are considered, sorbitol and glycerol, and broad guidelines are developed for using PEDOT/PSS as a hole‐injection electrode in polymeric light‐emitting devices, solar cells, and photodetectors.
The influence of annealing conditions on the physical properties of thin films of PEDOT/PSS is investigated. In particular, how the ambient gas (see Figure) and choice of dopant affect the conductivity, morphology, and work function of the films is explored.
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