The rumen liquid metatranscriptome of post-weaned dairy calves differed by pre-weaning ruminal administration of differentially-enriched, rumen-derived inocula.

Background: Targeted modification of the dairy calf ruminal microbiome has been attempted through rumen fluid inoculation to alter productive phenotypes later in life. However, sustainable effects of the early life interventions have not been well studied, particularly on the metabolically active rumen microbiota and its functions. This study investigated the sustained effects of adult-derived rumen fluid inoculations in pre-weaning dairy calves on the active ruminal microbiome of post-weaned dairy calves analyzed via RNA-sequencing.

Pre-weaning Ruminal Administration of Differentially-Enriched, Rumen-Derived Inocula Shaped Rumen Bacterial Communities and Co-occurrence Networks of Post-weaned Dairy Calves.

Adult rumen fluid inoculations have been considered to facilitate the establishment of rumen microbiota of pre-weaned dairy calves. However, the sustained effects of the inoculations remain to be explored. In our previous study, 20 pre-weaned dairy calves had been dosed with four types of adult rumen inoculums [autoclaved rumen fluid, bacterial-enriched rumen fluid (BE), protozoal-enriched (PE), and BE + PE] weekly at 3 to 6 weeks of age.

Microbial Inoculum Composition and Pre-weaned Dairy Calf Age Alter the Developing Rumen Microbial Environment.

The objective of this experiment was to determine if dosing pre-weaned calves with enriched ruminal microbiota alters the rumen microbial environment and growth performance. Twenty Holstein bull calves were removed from their dam at birth, fed 3.8 L colostrum within 4 h after birth, and housed individually.

Ultrafast photo-excitation dynamics in isolated, neutral water clusters.

Using the efficient nonlinear conversion scheme which was recently developed in our group [M. Beutler, M. Ghotbi, F.

Excimer states in microhydrated adenine clusters.

We present femtosecond pump-probe mass and photoelectron spectra for adenine (A) and microhydrated A(m)(H(2)O)(n) clusters. Three distinct relaxation processes of photoexcited electronic states were distinguished: in unhydrated A, relaxation of the optically bright pipi* state occurred via the dark npi* state with respective lifetimes of <0.1 and 1.

Observation of proton transfer in 2-aminopyridine dimer by electron and mass spectroscopy.

A photoinitiated intermolecular electron-proton transfer reaction in 2-aminopyridine dimer was investigated by femtosecond pump-probe electron-ion coincidence spectroscopy and accompanying theory. Excited-state population dynamics were observed in real time by time-resolved mass spectroscopy, and the respective excited-state character of locally excited and proton/hydrogen transfer states was identified in coincident electron spectra. Two reaction channels for an ultrafast (sub-50 fs) and a slower (approximately 75 ps) proton/hydrogen transfer were observed and indicate that vibrational energy redistribution may lead to efficient population trapping in the excited state.

Electronic structure of adenine and thymine base pairs studied by femtosecond electron-ion coincidence spectroscopy.

Femtosecond pump-probe spectroscopy was combined with photoelectron-photoion coincidence detection to investigate the electronic structure and dynamics of isolated adenine (A) and thymine (T) dimers and the adenine-thymine (AT) base pair. The photoelectron spectra show that pipi* and npi* states are only weakly perturbed in the hydrogen-bound dimers as compared to the monomers. For cationic base pairs with internal energies greater than 1 eV, we observed considerable cluster fragmentation into protonated monomers.

Ultrafast deactivation processes in aminopyridine clusters: excitation energy dependence and isotope effects.

Fast excited-state relaxation in H-bonded aminopyridine clusters occurs via hydrogen transfer in the excited state. We used femtosecond pump-probe spectroscopy to characterize the excited-state reaction coordinate. Considerable isotope effects for partially deuterated clusters indicate that H-transfer is the rate-limiting step and validate ab initio calculations in the literature.

Ultrafast processes in OClO molecules excited by femtosecond laser pulses at 386-409 nm.

Ultrafast dissociation dynamics in OClO molecules is studied, induced by femtosecond laser pulses in the wavelength region from 386 to 409 nm, i.e., within the wide absorption band to the (approximately)A (2)A(2) electronic state.

Relevance of pi sigma* states in the photoinduced processes of adenine, adenine dimer, and adenine-water complexes.

Ab initio calculations and time-resolved photoionization spectroscopy were carried out to characterize the role of the lowest two pi sigma* excited states for the photoinduced processes in the adenine monomer, adenine dimer, and adenine-water clusters. The calculations show--with respect to the monomer--a stabilization of 0.11-0.

Dynamics of photoinduced processes in adenine and thymine base pairs.

The excited-state dynamics of adenine and thymine dimers and the adenine-thymine base pair were investigated by femtosecond pump-probe ionization spectroscopy with excitation wavelengths of 250-272 nm. The base pairs showed a characteristic ultrafast decay of the initially excited pi pi* state to an n pi* state (lifetime tau(pi pi*) approximately 100 fs) followed by a slower decay of the latter with tau(n pi*) approximately 0.9 ps for (adenine)2, tau(n pi*) = 6-9 ps for (thymine)2, and tau(n pi*) approximately 2.

Efficient deactivation of a model base pair via excited-state hydrogen transfer.

We present experimental and theoretical evidence for an excited-state deactivation mechanism specific to hydrogen-bonded aromatic dimers, which may account, in part, for the photostability of the Watson-Crick base pairs in DNA. Femtosecond time-resolved mass spectroscopy of 2-aminopyridine clusters reveals an excited-state lifetime of 65 +/- 10 picoseconds for the near-planar hydrogen-bonded dimer, which is significantly shorter than the lifetime of either the monomer or the 3- and 4-membered nonplanar clusters. Ab initio calculations of reaction pathways and potential-energy profiles identify the mechanism of the enhanced excited-state decay of the dimer: Conical intersections connect the locally excited 1pipi* state and the electronic ground state with a 1pipi* charge-transfer state that is strongly stabilized by the transfer of a proton.

Effect of molasses supplementation on the production of lactating dairy cows fed diets based on alfalfa and corn silage.

Adding sugar to the diet has been reported to improve production in dairy cows. In each of 2 trials, 48 lactating Holsteins (8 with ruminal cannulas) were fed covariate diets for 2 wk, blocked by days in milk into 12 groups of 4, and then randomly assigned to diets based on alfalfa silage containing 4 levels of dried molasses (trial 1) or liquid molasses (trial 2). In both studies, production data were collected for 8 wk, ruminal samples were taken in wk 4 and 8, and statistical models were used that included covariate means and block.

Theoretical study of the hydrogen atom transfer in the heterodimer indole-ammonia and comparison with experimental results.

Ab initio calculations on the heterodimer C8H6NH...

Ultrafast predissociation dynamics of water molecules excited to the electronic C and D states.

Two-photon excitation with femtosecond laser pulses in the spectral range 240-250 nm was used to prepare vapor phase H(2)O and D(2)O in the C (1)B(1) and D (1)A(1) states. Both states are predissociated via the B (1)A(1) state, forming excited OH/OD(A (2)Sigma(+)) as well as ground state OH/OD(X (2)Pi). We used ultrashort infrared probe pulses (1.

Absolute extreme ultraviolet yield from femtosecond-laser-excited Xe clusters.

Large Xe clusters (10(5)-10(6) atoms per cluster) have been irradiated with ultrashort (50 fs) and high-intensity ( approximately 2 x 10(18) W/cm(2)) pulses from a Ti:sapphire multi-TW laser at 800 nm wavelength. Scaling and absolute yield measurements of extreme ultraviolet (EUV) emission in a wavelength range between 7 and 15 nm in combination with cluster target characterization have been used for yield optimization. Maximum emission as a function of the backing pressure and a spatial emission anisotropy covering a factor of two at optimized yields is discussed with a simple model of the source geometry and EUV-radiation absorption.