Relationship of senescence of corn (Zea mays L.) stalk pith, cob parenchyma and first developed leaf tissues to RNA content and synthesis

In stalk parenchyma tissue of WF9 X 38-11 single corn (Zea mays L.), there was a per cell increase in RNA synthesis and a slight increase in total RNA as cells became older. In cob parenchyma tissue of WF9 X 38-11 single cross corn, both total RNA content and RNA synthesis per cell decreased with the age of cells. In first developed leaf tissue of FR43 X FR14A single cross corn, RNA synthesis increased steadily but only slightly over its life span. The pattern of RNA synthesis and destruction in senescing leaf tissue of seedlings and two sources of parenchyma tissue of maturing plants appeared to differ.     

Tracheobronchiomegaly (Mounier-Kuhn syndrome)

Tracheobronchiomegaly is a rare congenital disorder due to defective development of elastic and muscle tissues in the upper airways. The characteristic radiologic features shown by bronchography include marked dilatation of the tracheobronchial system and diffuse saccular bronchiectasis. These findings and recurrent episodes of pneumonia lead to a progressive loss of pulmonary function. Even with vigorous medical therapy the prognosis is poor and severe respiratory failure eventually develops.     

Inhibition of HeLa cell messenger RNA translation by 7-methylguanosine 5'-monophosphate

Translation of HeLa cell RNA containing poly(A) in a wheat germ cell-free system is markedly but incompletely inhibited by 7-methylguanosine 5'-monophosphate (m7G5'p). We have analyzed the translation products synthesized in the presence of different concentrations of m7G5'p and find that translation of all mRNAs is equally inhibited. To demonstrate the specificity of the inhibitor for RNAs with 5'-terminal m7G5' ppp... we show that specific translation products of satellite tobacco necrosis virus RNA, which does not have this 5' terminus, are synthesized in the presence of m7G5' p. Protein synthesis programmed by endogenous mRNA in a HeLa cell-free system is inhibited after a 10-min lag by m7G5' p. Other guanosine nucleotides without the 7-methyl group or with the phosphate in a different position are not inhibitor. We show that translation of all mRNAs is inhibited to a similar extent by m7G5'p in the HeLa cell-free system, by synthesizing 35S-labeled proteins in the presence of different inhibitory concentrations of this nucleotide and analyzing the translation products by electrophoresis and autoradiography. Translation of encephalomyocarditis virus RNA added to the HeLa cell-free system is not inhibited by m7"g5p; this viral RNA does not have this nucleotide at the 5' terminus. This indicates that m7G5'p specifically inhibits translation of mRNAs with the 5' terminus m7G5'ppp... and suggests that initiation of translation of picornavirus RNA may proceed via a mechanism different from that of cellular mRNAs.     

Developmental patterns of acid hydrolases during differentiation of fetal mouse skin

A dye reduction method was developed for estimating total aerobic and/or psychrotrophic bacterial counts in ground beef. The method is based on color changes in indicator disks placed on the meat surface.     

Dairy herd management practices that impact nitrogen utilization efficiency

Improving the efficiency of feed N utilization by dairy cattle is the most effective means to reduce nutrient losses from dairy farms. The objectives of this study were to quantify the impact of different management strategies on the efficiency of feed N utilization for dairy farms in the Chesapeake Bay Drainage Basin. A confidential mail survey was completed in December 1998 by 454 dairy farmers in PA, MD, VA, WV, and DE. Nitrogen intake, urinary and fecal N, and efficiency of feed N utilization was estimated from survey data and milk analysis for each herd. Average efficiency of feed N utilization for milk production by lactating dairy cows (N in milk/N in feed x 100) was 28.4% (SD = 3.9). On average, farmers fed 6.6% more N than recommended by the National Research Council, resulting in a 16% increase in urinary N and a 2.7% increase in fecal N. Use of monthly milk yield and component testing, administration of bovine somatotropin (bST), and extending photoperiod with artificial light each increased efficiency of feed N utilization by 4.2 to 6.9%, while use of a complete feed decreased efficiency by 5.6%. Increased frequency of ration balancing and more frequent forage nutrient testing were associated with higher milk production, but not increased N utilization efficiency. Feeding protein closer to recommendations and increasing production per cow both contributed to improving efficiency of feed N utilization.     

The identification of antibacterial compounds for the development of enhanced media for the detection of foodborne fungi

In an effort to identify a more suitable antibiotic for utilization in mycological media, 12 food borne fungal species from various genera including Alternaria alternata, Aspergillus flavus, A. niger, Eurotium chevalieri, Fusarium moniliforme, Penicillium sp., Rhizopus stolonifer, Saccharomyces cerevisiae, Candida tropicalis, Geotrichum candidum, Rhodotorula glutinis and Kluyveromyces thermotolerans along with 21 chloramphenicol-resistant bacterial isolates from fresh produce and ATCC cultures of Pseudomonas aeruginosa, P. fluorescens, E. coli, Pectobacterium carotovorum, Bacillus cereus and Staphylococcus spp. were tested for their abilities to grow on dichloran rose bengal agar containing various levels of gentamicin, chlortetracycline or chloramphenicol. Results indicated that all fungal isolates except for Rh. glutinis and R. stolonifer grew well on all media tested. Rh. glutinis did not grow on media containing gentamicin whereas R. stolonifer produced very restricted or no growth on these media. All bacterial isolates from fresh produce, P. aeruginosa (ATCC 27853) and P. fluorescens (ATCC BAA-477) grew well at 100, 125 and 150 mg chloramphenicol/liter medium, but they did not grow on media containing chlortetracycline (100, 125, or 150 mg/L) or gentamicin (15, 25, or 35 mg/L). P. aeruginosa (ATCC 10145) grew well on media containing chloramphenicol or gentamicin, but not in the presence of chlortetracycline. P. carotovorum, E. coli, B. cereus and Staphylococcus spp. did not grow on any of the selective media tested.     

Phosphorus feeding levels and critical control points on dairy farms

A viable and cost-effective approach to managing P on dairy farms is to minimize excess P in diets, which in turn leads to less excretion of P in manure without impairing animal performance. A questionnaire survey was conducted, coupled with on-site feed and fecal sample collection and analysis on dairy farms in New York, Pennsylvania, Delaware, Maryland, and Virginia. The purpose was to assess dietary P levels and to identify critical control points pertaining to P feeding management. Survey responses, 612 out of 2500 randomly selected farms, revealed a wide range of dietary P concentrations for lactating cows, from 3.6 to 7.0 g/kg of feed DM. The mean was 4.4 g/kg, which was 34% above the level recommended by the NRC for 27.9 kg milk/d, the mean milk yield in the survey. Higher P concentrations in diets were not associated with higher milk yields (n = 98, R2 = 0.057 for the survey farms; n = 92, R2 = 0.043 for farms selected for on-site sampling). However, higher dietary P led to higher P excretion in feces (n = 75, R2 = 0.429), with much of the increased fecal P being water soluble. Phosphorus concentrations in diet samples matched closely with P concentrations in formulated rations, with 67% of the feed samples deviating <10% from the formulations. On 84% of the survey farms, ration formulation was provided by professionals rather than producers themselves. Most producers were feeding more P than cows needed because it was recommended in the rations by these consultants. In conclusion, P fed to lactating cows averaged 34% above NRC recommendations; to reduce excess dietary P, ration formulation is the critical control point.     

Diets deficient in rumen undegraded protein did not depress milk production

The objective of this study was to evaluate the National Research Council's recommendations for feeding levels of rumen undegraded protein (RUP) for cows fed a one-group total mixed ration. Sixty Holstein cows were paired by parity (1 to 6) and DIM (23 to 315) and were randomly assigned to one of two treatment sequences. Diets contained alfalfa silage (30% diet DM) and corn silage (26% diet DM), and were isonitrogenous (16% CP) and isocaloric (1.71 Mcal/kg). Soybean meal, protected soybean meal (Soy Best), and urea were used to make ration protein fractions that were predicted to be 35 or 29% RUP. The 35% RUP diet was formulated to provide 98 and 105% of the average requirement for RUP and rumen degraded protein (RDP), respectively. The ration containing 29% RUP provided 79 and 117% of average required RUP and RDP, respectively. All cows were group-fed the high RUP diet during a 2-wk pretreatment period, and then were fed one ration for 4 wk followed by the other for 4 wk according to their assigned treatment sequence. Data were collected in the last wk of each period. Mean milk production, milk fat, and milk protein were 32.6 kg/d, 4.35%, and 3.36%, respectively, with no treatment differences. Treatment response was not affected by degree of predicted RUP deficiency. National Research Council requirements for RUP may be too high for cows fed diets similar in energy to a one-group total mixed ration. Alternatively, estimates of RUP content of feedstuffs may be low.