Incorporation of dietary nitrogen from fish meal and pea meal ( Pisum sativum ) in muscle tissue of Pacific white shrimp ( Litopenaeus vannamei ) fed low protein compound diets

Stable isotope analyses were applied to explore the relative dietary nitrogen contributions from fish meal and pea meal (Pisum sativum) to muscle tissue of Pacific white shrimp postlarvae (141 ± 31 mg) fed low protein diets having different proportions of both ingredients as the sole dietary protein sources. A negative control diet was formulated to contain 100% pea meal and six more isoproteic diets to have decreasing levels of pea meal-derived nitrogen: 95%, 85%, 70%, 55%, 40% and 0% of the initial level. Growth rates were negatively correlated to dietary pea protein inclusion due to progressive essential amino acid deficiencies (sulphur amino acids, threonine, lysine, histidine). The nitrogen turnover rate significantly increased in muscle tissue of shrimps fed diets having high levels of pea meal; however, contrary to observations from a previous study using soy protein, the relative contributions of dietary nitrogen from pea meal to shrimp muscle tissue were equal or higher than expected contributions established by the dietary formulations. Results highlight the effectiveness of stable isotope analysis in assessing the nutritional contributions of alternative ingredients for aquaculture feeds and the potential suitability of pea as a source of protein (provided the diets are nutritionally balanced)

Chemical Reaction Dynamics of the Liquid/Vapor Interface Studied by Mass Spectrometry

This thesis presents investigations of chemical reactions occurring at the liquid/vapor interface studied using novel sampling methodologies coupled with detection by mass spectrometry. Chapters 2 and 3 utilize the recently developed technique of field-induced droplet ionization mass spectrometry (FIDI-MS), in which the application of a strong electric field to a pendant microliter droplet results in the ejection of highly charged progeny droplets from the liquid surface. In Chapter 2, this method is employed to study the base-catalyzed dissociation of a surfactant molecule at the liquid/vapor interface upon uptake of ammonia from the gas phase. This process is observed to occur without significant modulation of the bulk solution pH, suggesting a transient increase in surface pH following the uptake of gaseous ammonia. Chapter 3 presents real-time studies of the oxidation of the model tropospheric organic compound glycolaldehyde by photodissociation of iron (III) oxalate complexes. The oxidation products of glycolaldehyde formed in this process are identified, and experiments in a deoxygenated environment identify the role of oxygen in the oxidation pathway and in the regeneration of iron (III) following photo-initiated reduction. Chapter 4 explores alternative methods for the study of heterogeneous reaction processes by mass spectrometric sampling from liquid surfaces. Bursting bubble ionization (BBI) and interfacial sampling with an acoustic transducer (ISAT) generate nanoliter droplets from a liquid surface that can be sampled via the atmospheric pressure interface of a mass spectrometer. Experiments on the oxidation of oleic acid by ozone using ISAT are also presented. Chapters 5 and 6 detail mechanistic studies and applications of free-radical-initiated peptide sequencing (FRIPS), a technique employing gas-phase free radical chemistry to the sequencing of peptides and proteins by mass spectrometry. Chapter 5 presents experimental and theoretical studies on the anomalous mechanism of dissociation observed in the presence of serine and threonine residues in peptides. Chapter 6 demonstrates the combination of FRIPS with ion mobility-mass spectrometry (IM-MS) for the separation of isomeric peptides.

Glycogen Synthase Kinase 3 Influences Cell Motility and Chemotaxis by Regulating Phosphatidylinositol 3 Kinase Localization in Dictyostelium discoideum

Glycogen Synthase Kinase 3 (GSK3), a serine/threonine kinase initially characterized in the context of glycogen metabolism, has been repeatedly realized as a multitasking protein that can regulate numerous cellular events in both metazoa and protozoa. I recently found GSK3 plays a role in regulating chemotaxis, a guided cell movement in response to an external chemical gradient, in one of the best studied model systems for chemotaxis - Dictyostelium discoideum. It was initially found that comparing to wild type cells, gsk3- cells showed aberrant chemotaxis with a significant decrease in both speed and chemotactic indices. In Dictyostelium, phosphatidylinositol 3,4,5-triphosphate (PIP3) signaling is one of the best characterized pathways that regulate chemotaxis. Molecular analysis uncovered that gsk3- cells suffer from high basal level of PIP3, the product of PI3K. Upon chemoattractant cAMP stimulation, wild type cells displayed a transient increase in the level of PIP3. In contrast, gsk3- cells exhibited neither significant increase nor adaptation. On the other hand, no aberrant dynamic of phosphatase and tensin homolog (PTEN), which antagonizes PI3K function, was observed. Upon membrane localization of PI3K, PI3K become activated by Ras, which will in turn further facilitate membrane localization of PI3K in an F-Actin dependent manner. The gsk3- cells treated with F-Actin inhibitor Latrunculin-A showed no significant difference in the PIP3 level. I also showed GSK3 affected the phosphorylation level of the localization domain of PI3K1 (PI3K1-LD). PI3K1-LD proteins from gsk3- cells displayed less phosphorylation on serine residues compared to that from wild type cells. When the potential GSK3 phosphorylation sites of PI3K1-LD were substituted with aspartic acids (Phosphomimetic substitution), its membrane localization was suppressed in gsk3- cells. When these serine residues of PI3K1-LD were substituted with alanine, aberrantly high level of membrane localization of the PI3K1-LD was monitored in wild type cells. Wild type, phosphomimetic, and alanine substitution of PI3K1-LD fused with GFP proteins also displayed identical localization behavior as suggested by the cell fraction studies. Lastly, I identified that all three potential GSK3 phosphorylation sites on PI3K1-LD could be phosphorylated in vitro by GSK3.

DIETARY ESSENTIAL AMINO ACID SUPPLEMENTATIONS (In a Sex and Growth-Phase Split Feeding in Pig )

Penelitian ini bertujuan untuk menyelidiki pengaruh suplementasi ransum dasar (BD, ransum kontrol yang disusun menurut NRC, 1988) dengan asam amino esensial lysine, methionin, threonine (SD1 dan SD2, ransum perlakuan) terhadap konsumsi ransum dan kinerja pada ternak babi. Bahan utama ketiga ransum terdiri dari tepung barley, gandum, dan kedele. Masing-masing ransum mengandung kadar protein kasar (18% untuk grower dan 16,5% untuk finisher) dan enerji (14,2 MJ/kg). Ransum diberikan dengan cara dipecah (splitted) menurut periode pertumbuhan (grower dan finisher) dan jenis kelamin (jantan dan betina ). Ransum kg BB dan SDI dipecah menjadi 2 fase pemberian (grower: 20 - 60 kg berat badan (BB), dan finisher: 60 - 105 kg BB), ransum SD2 dipecah menjadi 4 fase pemberian (grower I: 20 - 40 kg, grower II:  40 - 60 kg, finisher I : 60 - 80 kg, dan finisher II: 80 - 105 kg BB).Babi dengan berat awal 20 kg sebanyak 72 ekor (36 jantan dan 36 betina) dikandangkan dengan kondisi lingkungan yang serupa (200C) selama penelitian. Suplementasi ransum dasar dengan asam amino esensial tidak mempengaruhi konsumsi ransum harian (2,49, 2,43, dan 2,36 kg masing-masing untuk BD, SD1 dan SD2, P>0,05). Babi pada masa pertumbuhan finisher mengonsumsi ransum harian terbanyak (2,77 - 2,83 kg) dibanding masa pertumbuhan lainnya (P<0,01). Babi jantan cenderung mengonsumsi  ransum harian  lebih banyak (P<0,11) dibanding babi betina (2,49 kg vs. 2,36 kg). Babi yang diberi ransum yang diperkaya dengan asam amino tumbuh lebih cepat (0,93 dan 0,96 kg/hari untuk SD1 dan SD2) dibanding babi yang diberi ransum kontrol (0,82 kg/hari), P<0,01. Pertumbuhan tercepat terjadi pada masa awal finisher (60 - 80 kg BB), yaitu 1,07 kg/hari, sedangkan kecepatan pertumbuhan pada masa pertumbuhan yang lain sebanding(0,85; 0,86; dan 0,83 kg/hari). Babi yang diberi ransum yang diperkaya dengan asam amino esensial dapat menggunakan ransum dengan lebih efisien (2,68 dan 2,58 kg ransum/kg PBB untuk SD1 dan SD2) dibanding babi yang diberi ransum kontrol (3,03 kg ransum/kg PBB), P<0.01. Diantara masa pertumbuhan, awal masa pertumbuhan grower (20-40kg BB) mempunyai efisiensi penggunaan ransum tertinggi(2,16 kg ransum/kg PBB) dan akhir masa pertumbuhan finisher (80-105 kg BB) mempunyai nilai efisiensi terendah(3,55 kg ransum/kg PBB),P<0.01. Babi jantan cenderung lebih efisien dalam menggunakan ransum dibanding babi betina (2,66 vs 2,87 kg ransum/kg PBB), P<0,09. (Animal Production 4(1): 1-10 (2002) Kata kunci: Ransum, suplementasi,asam amino, babi, konsumsi, kinerja