Middle Stone Age bedding construction and settlement patterns at Sibudu, South Africa

The Middle Stone Age (MSA) is associated with early behavioral innovations, expansions of modern humans within and out of Africa, and occasional population bottlenecks. Several innovations in the MSA are seen in an archaeological sequence in the rock shelter Sibudu (South Africa). At ~77,000 years ago, people constructed plant bedding from sedges and other monocotyledons topped with aromatic leaves containing insecticidal and larvicidal chemicals. Beginning at ~73,000 years ago, bedding was burned, presumably for site maintenance. By ~58,000 years ago, bedding construction, burning, and other forms of site use and maintenance intensified, suggesting that settlement strategies changed. Behavioral differences between ~77,000 and 58,000 years ago may coincide with population fluctuations in Africa.     

Symptoms in slash pine seedlings following inoculation with the cone rust fungus Cronartium strobilinum

Six‐week‐old seedlings of slash pine (Pinus elliottii) were inoculated with sporidia of Cronartium strobilinum, which is the cause of southern cone rust disease, by wounding the apical tips of the seedlings. Pycnial sori developed abundantly within 1 month of inoculation on the epicotyl and primary needles. The progress of the pathogen was confirmed histologically within the cells of the stem and haustoria were observed near the nucleus of the cells. In the needles, pycnial pustules developed and the fungus was abundant in the mesophyll.     

Wildfire Effects on Understory Vegetation,Natural Regeneration,and Forest Floor Fuels in a Sierran Mixed Conifer Stand

Wildfire effects on understory shrubs and herbs, regeneration of the seedling and sapling size classes, and downed and dead fuels were assessed in a mixed conifer stand located in the Lake Tahoe Basin in which California white fir (Abies concolor var. lowiana [Gord.] Lemm.) was most abundant but with Jeffrey pine (Pinus jeffreyi Grev. & Balf.) also prevalent. In burned and unburned stand portions, prefire measurements served as a basis of comparison for the postfire measurements pertinent to each study component. Fire severely suppressed the understory vegetation, which was dominated by shrubs such as bush chinquapin (Chrysolepis sempervirens [Kellogg] Hjelmqvist) and antelope bitterbrush (Purshia tridentata [Pursh] DC.), while a tepid postfire recovery of most of the preexisting species in the burned stand portion was augmented by new ones, including shrubs such as snowbrush (Ceanothus velutinus Douglas ex Hook.) and whitethorn (Ceanothus cordulatus Kellogg) ceanothus and herbs such as Holboell's rockcress (Arabis holboellii Hornem.). Tree seedling abundance was also substantially reduced in the burned portion, but the postfire population was dominated by Jeffrey pine whereas white fir had been most prevalent originally. Sapling regeneration was eliminated from the burned stand portion regardless of species. Downed and dead fuel loading was severely diminished by the fire, especially regarding fine fuels, permitting subsequent sheet erosion to imperil new seedling regeneration. These results contribute to an understanding of the direction and pace of postwildfire succession on sites occupied by Sierra Nevada mixed conifer and similar forest cover types, which is critical in decisions concerning the need for, and extent of, postfire site rehabilitation measures.     

Peptides isolated from in vitro digests of milk enhance iron uptake by caco-2 cells

Milk proteins, during digestion, produce a range of biologically active peptides. Among those are peptides that may enhance iron absorption. The objective of this project was to investigate the effect of isolated milk peptides on iron uptake. Cow's milk, 0% fat, was subjected to a modified in vitro digestion process. The milk digest was further fractionated by gel filtration. All eluted fractions as well as beta-casein synthetic peptides (a tripeptide and a hexapeptide) were subsequently tested for effects on iron uptake with Caco-2 cell monolayers. Fractions of milk digests obtained through Sephadex G-25 gel filtration had a significant enhancing effect on iron uptake in Caco-2 cells compared to nonfractionated milk digests. Two fractions (P = 0) and the hexapeptide (P < 0.0001) enhanced iron uptake by up to 3-fold, whereas others and the tripeptide had no effect. These results suggest that selected peptides produced during the in vitro digestion of milk may enhance iron absorption; however, it remains to be demonstrated whether this effect may be nutritionally significant.     

Assessment of shoreline vegetation in relation to use by molting black brant Branta bernicla nigricans on the Alaska coastal plain

To evaluate the importance of large thaw lakes on the Alaska Coastal Plain for molting Pacific black brant Branta bernicla nigricans, distribution and life form of shoreline vegetation were assessed using several scales: satellite imagery, point-intercept transects, cover quadrats, and a parameter for water regime. Brant population and distribution estimates from aerial surveys were used to classify large lakes into high, moderate, and low use. Correlations between brant and abundance of their preferred feeding site — moss flats — were best demostrated by satellite imagery. Intercepts and cover ratings were not correlated, presumably because these techniques were less efficient at assessing area. General observations suggested that the presence of islands, large ice floes, and possibly other physical attributes of the habitat, influenced brant distribution. This area is unique because of low-lying, drained-lake basins that have ideal combinations of moss flats and large water areas where brant seek protection disturbance is vital to the success of this declining species because alternate habitats may not be available elsewhere on the Coastal Plain. in water or on ice floes. Protection of the area from     

大麦黄矮病毒(BYDV) cDNA的合成、克隆及初步应用

 以大麦黄矮病毒二叉蚜和麦长管蚜专化株的病毒核酸为模板,以小牛胸腺DNA为引物,合成cDNA的第一条链,再用缺口翻译法合成第二条链,然后采用加装BamH₁人工接头的方法将ds-cDNA插入到质粒载体pUC₈中,重组质粒于大肠杆菌JM—83中进行克隆,以克隆的颜色变化选择含有外源DNA的克隆,再用病毒核酸制备的探针筛选真正病毒cDNA插入的克隆。重组质粒中ds-DNA的插入长度在300—1600bp之间。用缺口翻译法制备质粒DNA分子探针检测同源病毒液,反应灵敏度在100pg-1ng之间。应用cDNA探针检测不同病毒和病毒株系,从中筛选出黄矮病毒株系专化克隆系,黄矮病毒专化克隆系和黄矮病毒组专化克隆系.     

Clinical features of dilated cardiomyopathy in Great Danes and results of a pedigree analysis: 17 cases (1990-2000)

OBJECTIVE: To determine clinical features of dilated cardiomyopathy (DCM) in Great Danes and to determine whether DCM is familial in this breed. DESIGN: Retrospective study. ANIMALS: 17 Great Danes with DCM. PROCEDURE: Medical records of Great Danes in which DCM was diagnosed on the basis of results of echocardiography (fractional shortening < 25%, end-systolic volume index > 30 ml/m2 of body surface area) were reviewed. Pedigrees were obtained for affected animals, as well as for other Great Danes in which DCM had been diagnosed. RESULTS: Dilated cardiomyopathy appeared to be familial and was characterized by ventricular dilatation, congestive heart failure (left-sided or biventricular), and atrial fibrillation. Pedigree analysis suggested that DCM was inherited as an X-linked recessive trait, but the mode of inheritance could not be definitively identified. CONCLUSIONS AND CLINICAL RELEVANCE: Results suggest that DCM may be an X-linked recessive trait in Great Danes. Thus, dogs with DCM probably should not be used for breeding, and female offspring of affected dogs should be used cautiously. Male offspring of affected females are at an increased risk of developing DCM and should be evaluated periodically for early signs of disease. Results of pedigree analysis were preliminary and should be used only as a guide for counseling breeders, rather than as a basis for making breeding decisions.     

Use of echocardiography for the diagnosis of heartworm disease in cats: 43 cases (1985-1997)

OBJECTIVE: To determine the usefulness of echocardiography in the diagnosis of heartworm disease in cats and to compare this modality with other tests. DESIGN: Retrospective study. ANIMALS: 43 cats with heartworm infection that had echocardiographic examinations at 2 veterinary teaching hospitals between 1985 and 1997. Twenty-two of these 43 cats also underwent radiography of the thorax and heartworm antibody and heartworm antigen testing. PROCEDURE: Cats were determined to be infected with Dirofilaria immitis infection on the basis of 1 or more of the following findings: positive modified Knott or antigen test result, echocardiographic evidence of heartworm disease, or confirmation of the disease on postmortem examination. The percentage of echocardiographs in which heartworms were evident was compared with the percentage of radiographs in which pulmonary artery enlargement was evident and results of antigen or antibody tests in cats in which all tests were performed. RESULTS: Overall, heartworms were detectable by use of echocardiography in 17 of 43 cats, most often in the pulmonary arteries. In the 22 cats in which all tests were performed, antibody test results were positive in 18, antigen test results were positive in 12, and pulmonary artery enlargement was evident radiographically and heartworms were identifiable echocardiographically in 14. Heartworm infection was diagnosed exclusively by use of echocardiography in 5 cats in which the antigen test result was negative. CONCLUSIONS AND CLINICAL RELEVANCE: Although echocardiography was less sensitive than antigen testing, it was a useful adjunctive test in cats that had negative antigen test results in which there was a suspicion of heartworm disease. The pulmonary arteries should be evaluated carefully to increase the likelihood of detection of heartworms echocardiographically.