Nursery and site preparation interaction research in the United States

Researchers in the United States have generally taken a ``segregated' approach to regeneration research. As a result, trials involving nurserytreatments are usually separated from trials involving site preparationtreatments. Researchers have concentrated on just the main treatmenteffects. Little effort has been placed on examining potential interactionsbetween nursery and site preparation treatments. Only a few nursery bysite preparation (NxSP) studies have been established. The profession hasgenerally assumed that gains from nursery and site preparation treatmentsare simply additive, or that the relative gains from nursery treatmentswould be insignificant when compared to intensive site preparationtreatments. Both of these assumptions may be incorrect.This review examines some of the NxSP interaction trials that have beenestablished in the United States during the last half of the 20thcentury. We predict that as rotation ages for plantations decrease, the needfor NxSP interaction trials will increase. NxSP interaction studies will berequired if researchers wish to include both nursery and site preparationtreatments in their early establishment models. To date, only a fewestablishment models have been developed in the United States.     

Two new alkaloids from Hornschuchia obliqua

The stem and roots of Hornschuchia obliqua provided two new alkaloids, 4,5-didehydroguadiscine and demethoxyguadiscine. Four known alkaloids, roemerine, guadiscine, liriodenine and cleistopholine were also isolated. The structures of the novel compounds were elucidated by spectroscopic analysis, including 2D NMR and MS.     

Multipliers in a Central Place Hierarchy

Open economy multipliers, at the community level, capture only a portion of the system-wide impact of changes in local autonomous spending. Multiplier effects for the central place system will include the community-specific multiplier, where the autonomous expenditure was initiated, plus all of the cross-community multiplier effects generated through linkages among communities in the hierarchy. Import leakages, in the form of shopping at higher levels, result in “filtering up” of expenditure increases initiated at lower levels of the system. In an earlier paper (Olfert and Stabler 1994), community-level multipliers for a central place system in the Great Plains were estimated. In this paper, the distribution of direct and induced spending, resulting from autonomous spending increases initiated at particular levels of a central place hierarchy, is derived and empirically estimated over all levels of the hierarchy. Building on (1) own-community level multipliers, (2) an exhaustive set of cross-community multipliers are derived and empirically estimated. The combination of own- and cross-community multipliers produces (3) system-wide multipliers that show the system-wide impact of spending initiated at any level in the hierarchy. Finally, (4) level-specific impact multipliers resulting from autonomous spending originating at any (every) level in the system are calculated. Results indicate that the induced impact of autonomous expenditure increases anywhere in the system will be the greatest at the top of the hierarchy, that autonomous increases at higher levels have a larger local impact than they do at lower levels, and that equal expenditure increases across the hierarchy will have a disproportionate impact at the top of the hierarchy, as well, dueto a combination of higher own-community multipliers and spending up the hierarchy by residents of lower level centers.     

Assisted Selection by Specific DNA Markers for Genetic Elimination of the Kunitz Trypsin Inhibitor and Lectin in Soybean Seeds

Summary The antinutritional factors found in soybean, lectin (SBL) and Kunitz trypsin inhibitor (SKTI), are usually inactivated by heat treatment. However, residual activity of these factors can be found in several types of soy-derived products. Heat treatment does not completely eliminate these factors, and in addition it may considerably decrease protein solubility. The genetic elimination of these antinutritional factors could be an alternative to the heat treatment. This study aimed to develop soybean lines devoid of SKTI and SBL in their seeds. The population under study was obtained by crossing the normal cv. Monarca with a soybean line lacking SKTI and SBL. Specific DNA primers were designed for the identification of the recessive alleles that condition the absence of SKTI and SBL. F₂ seeds presenting the DNA markers that identify the recessive alleles were selected and the corresponding F₂ plants were backcrossed with the recurrent parent (‘Monarca’), producing the BC₁F₁ generation. The F₂ generation was analyzed by SDS-PAGE in order to confirm the genotypes of the F₂ selected. The segregation tests confirmed that these traits are governed by two genes that segregate independently.     

Evidence of sexuality in induced tetraploids of Brachiaria brizantha (Poaceae)

Difficulties in obtaining new breeding lines of Brachiaria (Trin.) Griseb., an important forage grass in Brazil, are mostly related to differences in ploidy among the accessions, and to apomixis, an asexual mode of reproduction. Usually, sexual accessions are diploid while apomicts are polyploid. Induced tetraploids of Brachiaria brizantha (A. Rich.) Stapf have been successfully obtained and this paper presents the results of a study of their reproductive modes and fertility. Despite frequent meiotic aberrations during microspore development, the induced tetraploids produced viable pollen and produced progeny after controlled self-pollination. Similarly to the original diploid sexual progenitor, embryo sacs of the Polygonum type with confirmed meiotic origin were present in the induced tetraploids suggesting chromosome doubling did not alter the reproductive mode. The embryo sac of the Polygonum type was also observed in progenies obtained after self and open pollination. Nevertheless, embryo sacs of the Polygonum and the Panicum types within the same ovule were observed in some progenies obtained after open pollination, probably having resulted from hybridization with tetraploid, apomictic plants. Indeed, the compatibility of the progeny with tetraploid, apomictic B. brizantha was confirmed by the formation of mature caryopses after controlled pollination. Evidence is presented that the induced tetraploids and their progeny are sexual plants and that they are compatible with natural tetraploid B. brizantha. The induced tetraploids will be useful for analyses of apomictic inheritance as well as in the development of sexual tetraploid lines in Brachiaria breeding programs.     

Light quality on the in vitro growth and production of pigments in the genus Alternanthera

In tissue culture, several chemical and physiological factors can influence the production of secondary metabolites. The growth response and increased secondary metabolite production generated by a high irradiance environment, can be used to determine a favorable habitat for the growth and conservation of medicinal plants. Thus, the present study aimed to evaluate the influence of light quality on growth and production of secondary metabolites in Alternanthera sessilis (L.) R. Br. ex DC. (sessile joyweed), Alternanthera philoxeroides (Mart.) Grisebach (alligatorweed), Alternanthera tenella Colla (joyweed), and Alternanthera brasiliana (L.) Kuntze (Brazilian joyweed) plants cultured in vitro. The species were grown in MS medium, for 45 days in different light qualities (blue, white, and red). Growth parameters and biochemical analysis were performed at the end of the study. The results show that the red light allowed a higher accumulation of biomass in most species; red and white light were great inductors for the production of betacyanin and the blue light favored the enhancement of flavonoids. In this manner, the quality of light can affect the betacyanin, betaxanthin, and flavonoid biosynthesis as well as growth patterns in the related Alternanthera species. Based on the data presented, we suggest that specific genes can encode the pigment production according to the light quality which exhibit distinct activation patterns in different plant species.     

Distinct adiponectin profiles might contribute to differences in susceptibility to type 2 diabetes in dogs and humans

Dogs develop obesity-associated insulin resistance but not type 2 diabetes mellitus. Low adiponectin is associated with progression to type 2 diabetes in obese humans. The aims of this study were to compare total and high molecular weight (HMW) adiponectin and the ratio of HMW to total adiponectin (S_A) between dogs and humans and to examine whether total or HMW adiponectin or both are associated with insulin resistance in naturally occurring obese dogs. We compared adiponectin profiles between 10 lean dogs and 10 lean humans and between 6 lean dogs and 6 age- and sex-matched, client-owned obese dogs. Total adiponectin was measured with assays validated in each species. We measured S_A with velocity centrifugation on sucrose gradients. The effect of total and HMW adiponectin concentrations on MINMOD-estimated insulin sensitivity was assessed with linear regression. Lean dogs had total and HMW adiponectin concentrations three to four times higher than lean humans (total: dogs 32 ± 5.6 mg/L, humans 10 ± 1.3 mg/L, P<0.001; HMW: dogs 25 ± 4.5 mg/L, humans 6 ± 1.3 mg/L, P<0.001) and a higher S_A (dogs: 0.78 ± 0.05; humans: 0.54 ± 0.08, P = 0.002). Adiponectin concentrations and S_A were not lower in obese dogs (0.76 ± 0.05 in both groups; P=1). Total adiponectin, HMW adiponectin, and S_A were not associated with insulin sensitivity in dogs. We propose that differences in adiponectin profiles between humans and dogs might contribute to the propensity of humans but not dogs to develop type 2 diabetes. Dogs with chronic, naturally occurring obesity do not have selectively reduced HMW adiponectin, and adiponectin does not appear to be important in the development of canine obesity-associated insulin resistance.     

Exercising Blood Gas Analysis, Dynamic Upper Respiratory Tract Obstruction, and Postexercising Bronchoalveolar Lavage Cytology—A Comparative Study in Poor Performing Horses

Respiratory abnormalities are common causes of decreased performance in horses presumably because of impaired pulmonary gas exchange. The objectives of the present study were to describe respiratory abnormalities in poorly performing horses and to investigate the relationships between dynamic upper respiratory tract (URT) videoendoscopy, postexercising bronchoalveolar lavage (BAL) cytology, and exercising arterial blood gas analysis. Medical records of 93 horses with exercise intolerance, which presented for treadmill evaluation, were reviewed. Relationships between horse demographics, treadmill endoscopic findings, exercising blood gas values, and BAL cytology results were examined. A total of 25 (27%) horses had a URT obstruction and 91 (98%) horses had abnormal BAL cytology; 73 (78%) had evidence of inflammatory airway disease (IAD) and 83 (89%) had exercise-induced pulmonary hemorrhage (EIPH). In all, 39 (42%) horses had abnormal blood gas values. Dynamic URT obstruction was significantly associated with exercising hypoxemia (P = .036). There were no significant relationships between gas exchange and IAD or between EIPH. Out of 24 (26%) horses with combined URT obstruction and abnormal BAL, horses with URT obstruction and EIPH were more likely to be hypoxic during exercise (P = .037). It was concluded that horses with dynamic URT abnormalities are likely to have exercising hypoxemia. Although IAD and EIPH were commonly indentified in poor performers, they were not significantly associated with abnormal exercising blood gas analysis.     

Effect of diets containing potato protein or soya bean meal on the incidence of spontaneously-occurring subclinical necrotic enteritis and the physiological response in broiler chickens

1. An experiment was conducted to compare and explain the incidence of spontaneously occurring subclinical necrotic enteritis in broiler chickens that were fed on two practical broiler diets that differed in the major protein concentrates (soya bean meal or potato protein concentrates) and examine the relationships between the severity of the disease and the growth performance and physiological responses of the chickens. 2. A total of 840, 20-d-old birds were randomly allocated to 12 pens. Two maize-based nutritionally complete diets that either contained some potato protein or soya bean meal as the major protein supplement were fed for 16 d. Twelve birds were randomly sampled from each pen at the end of the feeding period and their blood sampled and intestinal tracts and livers dissected. 3. The birds fed on the potato protein diet had a significantly 7·7% lower feed intake and a significantly 7·8% lower growth rate compared with the birds fed on the soya-based diet. There were no significant differences in feed conversion efficiency or mortality. There were no differences in the determined apparent metabolisable energy concentrations, however, the apparent dry matter digestibility of the potato protein diet was significantly higher than that of the soya based diet and the apparent crude protein digestibility of the potato protein diet was significantly lower. 4. A significantly higher alpha toxin antibody titre was found in the birds fed on the potato protein diet compared with those fed on the soya protein diet. There was a significantly increased incidence of hepatic lesions in the birds fed on the potato protein diet compared with the birds fed on the soya diet. The mean incidence of intestinal necroses tended to be greater in the birds fed on the potato protein diet (23·6%) compared with the birds fed on the soya-based diet (15·3%). 5. There was a significant linear relationship between ileal digesta sialic acid concentration and serum alpha toxin antibodies, although there were a considerable number of outliers to this relationship. Measurement of sialic acid concentration may be a useful variable to indicate the severity of necrotic enteritis in broiler flocks.