Radioisotope and stable isotope ratios (Δ14C, δ15N) suggest larval lamprey growth is dependent on both fresh and aged organic matter in streams

Lampreys have a complex life cycle which includes a multi‐year infaunal larval stage (ammocoete). Gut content analysis has generally identified detritus (i.e., unidentifiable organic matter) as the major dietary component to ammocoetes, though algae can also be important. However, gut content preserves only a snapshot of the animal's diet and does not reflect assimilated material. In order to better characterise the nutritional sources supporting ammocoete growth, we analysed ammocoete body tissue and potential dietary sources at two streams using natural Δ¹⁴C and δ¹⁵N to estimate time‐integrated nutritional support. Bayesian isotope mixing models revealed differences in the importance of sources supporting ammocoetes between sites. Ammocoetes from a stream in a mixed land usage area (~50% agriculture, ~40% forest and ~10% developed) were primarily supported (mean: ~50%) by fresh terrestrial organic matter but were also supported by substantial contributions (mean: ~30%) by aged organic matter (AOM) and autochthonous material (algae; mean ~20%). In a predominantly forested (~90%) headwater stream, different modelling scenarios (uninformed or informed priors) suggested that algal support of ammocoete nutrition ranged from 7% to 45%. However, the model relying on informed priors developed from gut content analysis produced the low estimates, suggesting these were more reliable. When algae were a minor component of the nutrition at the forested site, ammocoetes were highly dependent on AOM (83 ± 26%; mean ± SD). Based on these findings, ammocoete growth and development are predicted to be strongly influenced by both land use and the availability of allochthonous and autochthonous materials of varying ages within streams.     

Temporal ELISA response of rams to Brucella ovis following experimental infection or vaccination

Sera from rams vaccinated with antigens extracted chaotropically from Brucella ovis by potassium thiocyanate treatment were used to optimise a whole-cell, enzyme-linked immunosorbent assay (CELISA) and to monitor the temporal serological response of rams which had been challenged with infected semen by the intranasal or intrapreputial route. Three patterns of CELISA response were detected. Thirteen of 15 rams intranasally challenged did not respond serologically (pattern 1 or nil response). Only one of 15 rams in the intranasal group exhibited a rise and fall response with CELISA (pattern 2), while another showed a rise and surge response (pattern 3). The numbers of rams in the intrapreputial group which displayed a pattern 1 or 2 or 3 response were four, nine and two, respectively. No ram with a pattern 2 response excreted B ovis in the semen or showed any other evidence of infection, whereas rams with a pattern 3 response excreted B ovis in the semen and developed palpable lesions. Intrapreputially challenged rams that were CELISA-positive consistently mounted an antibody response against B ovis about two to four weeks earlier than intranasally challenged rams.     

MAGNETIC RESONANCE, ULTRASOUND AND HISTOPATHOLOGIC CORRELATION OF ACUTE AND HEALING EQUINE TENDON INJURIES

Ultrasonography and MRI have become valuable tools for imaging of tendon injuries. The current study examines the histopathologic basis for the imaging abnormalities. Five injured equine forelimbs and two normal contralateral limbs were studied with high resolution real time ultrasound and MRI. Histologic sections were made and correlated with the diagnostic images. All lesions were readily seen by both modalities. Lesions characterized by hemorrhage, edma, and cellular infiltration were sonolucent on ultrasound and bright on MRI images. MRI returned to normal as fibrogenesis ensued. Ultrasound images remained abnormal until fibrillar reallgnment occured with completion of the healing process. High resolution real time ultrasound and MRI both accurately reflect the tissue abnormalities in acute tendon injuries. The injured horse does appear to be an effective model for correlative imaging studies of tendon injuries.     

Beef feedlot industry.

The United States cattle feeding sector has changed dramatically over time. Movement from an industry largely populated by farmer feeders using livestock to market their grain production to an industry composed of large, specialized, commercial cattle feeding firms has occurred since the end of World War II. Moreover, the industry also shifted geographically, moving away from the Corn Belt to the Plains as farmer feeders exited the industry. Today, the 10 largest firms in the industry likely market 22% to as much as 29% of all fed cattle produced in the United States. The shift in industry structure was at least partially motivated by the advent of improved technology. Successful implementation of rapidly evolving technology often required more intense, specialized management (and in some cases, larger operations) than was available in many farmer feeder operations. The ongoing shift away from live-weight pricing of fed cattle toward grid-based pricing could increase the need for specialized management yet again, encouraging even more industry consolidation in the future.     

Enhanced recovery of avian influenza virus isolates by a combination of chicken embryo inoculation methods.

Since 1993, 14 cases of avian influenza from four different states in the U.S.A. have been diagnosed by virus isolation from eight avian species. Only 11 of the 14 avian influenza virus (AIV) primary isolations would have been successful if only the standard protocol for AIV isolation, i.e., inoculation of specific-pathogen-free embryonating chicken eggs (ECEs) by the chorioallantoic sac (CAS) route, had been followed. Primary isolation attempts were negative for AIV in three cases in which ECEs were inoculated by the CAS route; AIV could not be detected by hemagglutinating activity, agar gel immunodiffusion test or negative stain electron microscopy. However, in these three cases, primary isolations of AIV were achieved by inoculation of ECEs into either the yolk sac or onto the chorioallantoic membrane.     

Artificial Spawning of Tilapia Eggs1

A stripspawning methodology was evaluated for tilapia (oreochromid) species. This technique achieved an average hatching success of 68.6 ± 3.6% (N= 31). Female fecundity and spawning frequency were dependant on both genetical and husbandry factors. Egg yields for Oreochromis niloticus, O. mossambicus, and O. niloticus±O. mossambicus hybrids averaged 4.54, 10.86 and 10.36 eggs/g female/spawn, respectively. Female broodstock that were adapted to an intensive spawning regime exhibited a significant increase in fecundity. Additionally, egg survival was not affected by hydration for up to 15 minutes prior to fertilization. Results suggest that the strip spawning of tilapia species may be an efficient method of providing viable gametes for hatchery purposes.     

杂交小麦大幅度提高产量优势新途径

与常规品种比较,杂种小麦总光合生物产量优势明显,但输入到籽粒中的光合产物比例较小,或产量结构不够理想,其产量优势不突出。因此,杂种小麦要突破生产应用关仍需寻找突破口。笔者根据多年从事常规小麦育种研究结果,提出杂种小麦、化学杂种小麦大幅度提高产量优势的新途径。