Search

Twelve Holsteins in first lactation were used to investigate the relationship between energy balance and effects of bovine somatotropin (bST) on thyroid hormone metabolism and cytokine concentrations in serum. Six cows were fed for ad libitum intake and six cows were feed restricted to induce negative energy balance during two treatment periods of 6 d. During treatment periods, cows were administered vehicle or 40mg of bST/d according to a crossover design. Between treatment periods was a 15-d recovery period, during which all cows were fed ad libitum. Cows that were fed ad libitum remained in positive energy balance during control and bST treatments, whereas cows that were fed for restricted intake were in negative energy balance during control and bST treatment periods. In both dietary groups, bST decreased energy balance. Milk production and the fat percentage of milk increased during bST treatment in both dietary groups. Fat-corrected milk yield was increased 13% by bST treatment. Serum concentrations of IGF-I did not differ between dietary groups but were greater during bST than control periods. Serum thyroxine concentration was decreased by bST treatment. Serum triiodothyronine and reverse-triiodothyronine were not altered by hormone treatment, but circulating concentrations of thyroid hormones were apparently reduced by dietary restriction. Neither hepatic nor mammary thyroxine 5’-deiodinase was affected by bST treatment. Plasma concentration of tumor necrosis factor-α, a potential regulator of thyroxine 5’-deiodinase, was not affected by bST treatment. Short-term treatment with bST did not influence thyroid hormone metabolism in lactating cows in positive or negative energy balance.

This investigation evaluated mammary cell loss and replacement during lactation and the impact of administration of bST on these processes. During lactation, a gradual decrease in number of mammary epithelial cells within the mammary glands occurs and largely accounts for the decline in milk production with advancing lactation. This decrease is not appreciably impacted by the loss of viable epithelial cells in milk. Rather, the net decline in cell number (∼50% during the entire lactation) results from continual death by apoptosis. Accompanying the decline in mammary cell number by apoptosis is a degree of cell renewal. Approximately 0.3% of mammary cells in lactating, nonpregnant cows were labeled by a 24-h in vivo treatment with the thymidine analog, bromodeoxyuridine. During the entire lactation, the number of new cells amounts to approximately 50% of the number of cells initially present. By the end of lactation, most cells present in the mammary gland were formed after calving. Increasing cell replacement or decreasing apoptosis during lactation may provide a means to increase persistency of lactation. Indeed, administration of bST to Holstein cows during midlactation increased the proportion of mammary epithelial cells expressing the nuclear proliferation antigen, Ki-67, from 0.5 to 1.6%. Bovine somatotropin appears to increase the rate of cell renewal in the lactating mammary gland. Knowledge of molecular regulation of apoptosis and cell proliferation should provide a means to modulate cell turnover in the mammary gland. A change in the ratio of epithelial proliferation to cell death during lactation will affect the persistency of lactation.

AbstractFollowing attack by Dendroctonus brevicomisLeConte, ponderosa pines were periodically sampled over 7 weeks. Xylem water conduction was assessed using a dye flow technique. Fungal isolations were made from functioning and occluded xylem. Neither Ophiostoma nigrocarpum(Davids.) de Hoog or other bluestain fungi were commonly found at the interface of the occluded and functioning xylem. Instead, blue-stain fungi appear to colonize already occluded xylem, not cause xylem occlusion by direct hyphal penetration of functioning sapwood. No evidence for a mutualistic association of D. brevicomisand its vectored bluestain fungi was found.

AbstractSurvival and development of Ips paraconfususLanier larvae reared individually in intact Pinus ponderosaLaws. phloem without associated fungi and dietary supplements was demonstrated. Survival was reduced.in intact ponderosa pine phloem previously occupied by other larvae or by bluestaining fungi [i.e. Ophiostoma ips(Rumb.) vectored by I. paraconfusus, O. minus(Hedge.) H. & P. Syd. vectored by Dendroctonus brevicomisLeConte, O. clavigerum(Robins.-Jeff. & Davids.) vectored by D. ponderosaeHopkins, and Leptographium terebrantisBarras & Perry vectored by D. valensLeConte] compared with those reared without fungi or symbiotic yeasts. The highest proportion of larvae initiating tunnels and surviving to adult was observed for untreated eggs, and the lowest proportion occurred in the L. terebrantistreatment. Size was reduced and developmental rate was slower for larvae reared without fungi compared with larvae reared with associated fungi.Tunnels excavated by first- and second-instar larvae reared without associated fungi were longer than those excavated by larvae reared with associated fungi. The most frequent larval turnabouts occurred with larvae reared axenically and reared with Ipsyeast and O. ips. The fewest occurred with larvae reared with Ipsegg niche plugs and from untreated eggs. Females reared free of any fungi or with Penicilliumor Aspergillusdid not oviposit in surface-sterilized ponderosa pine logs. Naturally eclosed females from ponderosa pine logs in which they developed, laid eggs in these sterilized logs. Potential for a new association among bark beetles and fungi is discussed.

We studied differences in lipid composition of milk from Jersey cows with US sires and from Jersey cows with Danish sires. Milk samples were obtained on DHIA test day from 32 cows with Danish sires and 32 herdmates with US sires in two herds. The Jerseys with US sires were paired with those with Danish sires by parity and stage of lactation. Mean percentage of milk fat was 5.7% for Jerseys with Danish sires and 4.8% for Jerseys with US sires. Total fat per day was the same (.91kg) for both groups. Detailed analysis of milk lipids indicated that lipid composition of milk was similar for cows with US sires and those with Danish sires. However, milk from Jerseys with Danish sires contained more free cholesterol than milk from Jerseys with US sires, 17.5 versus 14.3±.6 mg/dl. The proportion of polyunsaturated fatty acids was greater for milk from Jerseys with US sires than for milk from Jerseys with Danish sires (2.3 vs. 2.1%). Although lipid composition of milk from both groups was generally similar, the milk of Jersey cows with Danish sires had higher concentrations of free cholesterol and lower proportions of polyunsaturated fatty acids, both of which are possible negative factors for health of consumers.

Lipids in milk and blood were examined in Holstein and Jersey cows (8 lactating and 4 dry) fed two TMR containing either 10% whole cottonseed or a control concentrate mixture of corn, cottonseed hulls, and cottonseed meal in a switchback experiment. Milk from Jersey cows contained more total lipid than did milk from Holstein cows (4.4 vs. 3.5 g/dl), had a higher proportion of lipid as triglyceride (97.3% vs. 96.7%), and had a lower proportion of lipid as phospholipid (0.8% vs. 1.0%). Milk from the group fed cottonseed contained fewer medium-chain fatty acids (24.4% vs. 29.4%) and more C18fatty acids (35.9% vs. 25.8%) than did milk from the control group. Total blood lipids were 234 mg/dl for Holsteins and 168 mg/dl for Jerseys. Total blood lipids were higher for dry cows fed cottonseed (100 vs. 72 mg/dl), particularly Jersey cows. As determined by gravimetric or TLC analysis, milk fat percentages of cows fed cottonseed were not different from those of cows fed control rations. However, as determined by infrared instrumentation, milk fat appeared to be lower (4.3%) for cows fed cottonseed than that (4.6%) for control cows. Changes in milk fatty acids that were related to diets might explain the difference between infrared and gravimetric determinations of milk fat.

Four groups of 400 12-week-old CBA/H mice were injected i.p. with 69, 139, 280 and 550 Bqg-1 224Ra. A further group of 400 mice were injected i.p. with diluting solution only. The mice were then allowed unrestricted access to food and water until they died or were killed. 53 cases of myeloid leukaemia and 22 cases of osteosarcoma were confirmed in the 2000 mice injected, and for both tumour types direct relationships were shown to exist between the amount of 224Ra administered and the incidence of tumours. It is concluded that mouse is at a greater risk from myeloid leukaemia than from osteosarcoma in the region of administered 224Ra below that which causes a maximum yield of osteosarcoma. These results are discussed in the light of the present acceptance of osteosarcoma as the major risk to man from bone-seeking α-particle emitters.

Not Available

AbstractIps mexicanus(Hopkins) and I. paraconfususLanier can transmit a frugal pathogen that causes pitch canker [Fusarium subglutinans(Wollenw, and Reink.) Nelson, Toussoun, andMarasas], a disease recently identified in Monterey pines (Pirns radiataD. Don) in California. In Santa Cruz County, F. subglutinanswas recovered from Ipsspp. that emerged from pitch canker-in fee ted P. radiataand were captured in multiple-funnel traps baited with racemic Ipsspp. pheromones. Ips paraconfususadults experimentally contaminated with propagules of the fungus transmitted it to seedlings and mature pines. Field transmission was demonstrated when cankers were produced following pheromone-induced beetle attacks on pines. Ipsspp. inoculated F. subglutinansinto pine slash, thus creating reservoirs of this fungus. Larvae, pupae, and young adults acquired the fungus when their parents introduced it into logs. Ipsspp. progeny production and development were not significantly altered by the fungus. In proximity to other bark beetle-associated fungi, growth of F. subglutinanswas reduced and patchy. A new association may be developing among native Ipsspp. and F. subglutinans.

AbstractTo test the hypothesis that bark beetles and some associated insect species are attracted to ponderosa pines infected by Ceratocystis wageneri, insect visitations on 11 severely diseased, 9 moderately diseased, and 10 apparently healthy trees were monitored from 1 August to 15 October 1972. Larger numbers of Dendroctonus brevicomis, D. ponderosae, Temnochila chlorodia, and buprestids were captured on diseased trees uninfested by bark beetles than on apparently healthy ones, thus possibly indicating attraction to diseased trees. There was strong evidence that D. valensand Spondylis upiformiswere attracted more frequently to wounds on diseased than on healthy trees. Arrival patterns of beetles were recorded for trees that became infested during the study. Predators became abundant on traps as bark beetle catches increased.

Methods for mass producing pheromone-laden male frass in kg quantities are described. Individual male productivity is 9·4 mg/day and lasts for about 15 days. Three kg were utilized in the described isolation work. Experiments established decisively the presence of the pheromone on and throughout the dense faecal pellet. The attractant was found to be present in frass produced by males boring in white fir and Douglas fir, indicating that the sex pheromone does not function in initial host discrimination. A previously described bio-assay which utilizes simultaneously released groups of female or male beetles was refined. Their movement to the source of the attractant and their klinotactic behaviour in the olfactometer established the basis of the bio-assay. A detectable response is evoked by dilutions of benzene extracts equivalent to 3 × 10−8g of frass, which is about that produced by one male in one-third of a second. Isolation is initiated by soaking and pulverizing the frass several times in warm benzene. Benzene was removed by distillation and the concentrate distilled over a short path under reduced pressure. The distillate was chromatographed on silica gel by gradient elution with an ethyl ether-benzene mixture. Two internal markers bracketing the active silica gel fraction were identified as nonanal and geranyl acetate. The active fraction was subjected to gas-liquid chromatography, using a column of silicone rubber SE 30 on Chromosorb G, and good recovery of active material was achieved representing only 0·0007 per cent of the weight of starting material. Further GLC fractionation was performed on Carbowax 20M with the activity occurring as a number of partially resolved minor peaks.

Halocarbon fluids (FXCCF2)n, where X = Cl or Br have been used to index-match silica in the 800–2000 nm region. These fluids, unlike silicones or hydrocarbon fluids, are free of CH and OH absorption, and are resistant to hydrolysis and moisture absorption.

A 25 cm−1splitting of one of the fluorescence lines of Cr3+in LiGa5O8is reported. This cannot be explained by a pure electronic splitting of the Cr3+levels. An explanation is offered in terms of a strong interaction between the Cr3+and a local vibrational mode.