Metabolizable energy requirements for maintenance and growth of Awassi lambs

Twenty four Awassi lambs (mean BW 24.4 kg) were used in a two periods experiment to measure maintenance (zero growth) and growth requirements of metabolizable energy (ME). During the pre-treatment period (period 1, 3 weeks) all lambs were maintained at a constant level of feed intake (2% BW). During the treatment period (period 2, 10 weeks) the lambs were divided into four equal groups and fed different amounts (2, 3, 4 and 5% of BW). Six additional lambs of similar BW and age were killed at the beginning of the experiment to compare final empty body weight (FEBW) with initial body weight (IBW). Twelve lambs, divided into four equal groups were fed the experimental diet in the same amounts as in the growth experiment (period 2) to determine the digestibility of energy.

Energy requirement for maintenance (EM) was measured by both constant weight technique, using data collected during period 1, and regression technique by regressing ME intake on body weight gain (BWG) and empty body weight gain (EBWG). EM measured during the constant weight period (pre-treatment) and overall experimental period (pre-treatment plus treatment periods) were 0.482 and 0.466 MJ of ME per kg M^0.75 per day. Predicted energy requirements for growth (Eg) calculated from equations derived during the treatment period were 0.433, 0.623, 0.782, 0.910 and 1.007 (MJ per kg M^0.75 per day) for the growth rates 50, 100, 150, 200, and 250 (g per day) respectively. It is concluded to be more appropriate to use the values derived during the overall experimental period for maintenance and the overall treatment period for growth as they are most applicable to production situations.     

Purification and properties of a hemagglutination factor from Arabian Gulf catfish (Arius thalassinus) epidermal secretion

A galactose specific lectin was isolated from an epidermal proteinaceous gel secretion of the Arabian Gulf catfish, Arius thalassinus, Ruppell. The lectin was extracted and purified to near homogeneity by exclusion chromatography, affinity chromatography and isoelectric focusing. The lectin appears to be active as a single polypeptide chain with a mol. wt near 200,000, which can form oligomers and heteropolymers. The lectin comprises about 2% of the total gel protein, lacks carbohydrates and contains no unusual types or amounts of amino acids. The lectin agglutinates a wide range of red blood cell types.     

Cellulolytic Bacteria in the Foregut of the Dromedary Camel (Camelus dromedarius)

Foregut digesta from five feral dromedary camels were inoculated into three different enrichment media: cotton thread, filter paper, and neutral detergent fiber. A total of 283 16S rRNA gene sequences were assigned to 33 operational taxonomic units by using 99% species-level identity. LIBSHUFF revealed significant differences in the community composition across all three libraries.     

A role for wingless in an early pupal cell death event that contributes to patterning the Drosophila eye

Programmed cell death (PCD) is utilized in a wide variety of tissues to refine structure in developing tissues and organs. However, little is understood about the mechanisms that, within a developing epithelium, combine signals to selectively remove some cells while sparing essential neighbors. One popular system for studying this question is the developing Drosophila pupal retina, where excess interommatidial support cells are removed to refine the patterned ommatidial array. In this paper, we present data indicating that PCD occurs earlier within the pupal retina than previously demonstrated. As with later PCD, this death is dependent on Notch activity. Surprisingly, altering Drosophila Epidermal Growth Factor Receptor or Ras pathway activity had no effect on this death. Instead, our evidence indicates a role for Wingless signaling to provoke this cell death. Together, these signals regulate an intermediate step in the selective removal of unneeded interommatidial cells that is necessary for a precise retinal pattern.     

A highly sensitive assay for adenosine triphosphate employing an improved firefly luciferase reagent

An improved firefly luciferase reagent allowed reliable detection of as little as 80 fmo1/1 adenosine triphosphate (ATP). Contamination by ATP of the deionized water diluent limited the sensitivity of the assay in some laboratories. The reagent can be used to measure ATP from less than ten bacterial cells if care is taken to eliminate ATP from equipment and reagents.     

Comparative electrophoretic studies of muscle and eye lens proteins in freshwater fish of Iraq

Muscle myogens and eye lens proteins have been studied in ten species of freshwater fish from Iraq. The electrophoretic analysis revealed that the muscle myogens can be considered as a good taxonomic criterion to differentiate the family Mugilidae from the Cyprinodontidae and Cyprinidae, but not between the families Poeciliidae and Cyprinodontidae. Within the Cyprinidae the muscle myogens can be used to diferentiate Barbus grypus from the remaining species of this family. Eye lens proteins are not considered a good taxonomic criterion to differentiate the members of the four families studied, but can distinguish B. belawayei and B. grypus from the other Cyprinid species.     

Oospore production of Pythium artotrogus

The addition of cholesterol, b-sitosterol, stigmasterol and compost infusion to corn meal agar induced marked increases (four-fold) in oospore production, with only a small stimulation of growth rate. Progesterone stimulated oospore production, but inhibited growth. Estrone had no effect on reproduction, but inhibited growth. Testosterone greatly inhibited both growth and reproduction. The optimum concentration of cholesterol for maximum oospore production was 20–100 mg per liter. Growth and oospore production occurred over the initial pH range of 4.5–8.5, and over the temperature range of 12–38°C. Growth occurred at 9°, but no oospores formed. Cholesterol increased the temperature tolerance of the mycelium. Nystatin had no effect on growth or reproduction at 15 mg per liter; filipin and fungichromin completely prevented, and amphotericin B strongly inhibited oospore production at this concentration. Fungichromin was the most inhibitory to growth, filipin was intermediate and amphotericin B only slightly inhibitory. Cholesterol (15 mg/liter) annulled the growth inhibition, but not the inhibition of reproduction. Fluorodeoxyuridine and bromodeoxyuridine inhibited growth and oospore production. Deoxyadenosine had no effect. These experiments indicate that the metabolic processes involved in mycelium synthesis are markedly different from the processes involved in sexual reproduction since they were affected differently by the sterols, antibiotics, and the thymidine analogues.

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Zusammenfassung Der Zusatz von Cholesterol, beta Sitosterol, Stigmasterol und Kompost Infusion zu Maismehlagar verursachte eine vierfache Zunahme der Oosporenbildung, mit nur einer geringen Stimulierung des Wachstumanteiles. Progesterone stimulierte die Oosporenbildung, verhinderte jedoch das Wachstum. Estrone hat keine Wirkung an Reproduktion, aber verhinderte das Wachstum. Testosterone verhinderte wesentlich sowohl das Wachstum als auch die Reproduktion. Die optimale Konzentration von Cholesterol war für die höchste Oosporenbildung 20–100 mg pro Liter. Wachstum und Oosporenbildung erfolgte über die ursprüngliche pH-Weite von 4.5–8.5, und über die Temperaturweite von 12°–38°C. Wachstum erfolgte bei 9°C, aber keine Oosporenbildung. Cholesterol vergrößerte die Temperaturtoleranz des Myceliums. Nystatin hat keinen Einfluß an Wachstum oder Reproduktion bei 15 mg pro Liter: Filipin und Fungichromin verhinderte völlig und Amphotericin B sehr stark die Produktion bei dieser Konzentration. Fungichromin B Zeigte nur eine geringe Wachstum, Filipin war in der Mitte und Amphotericin B zeigte nur eine geringe Verhinderung. Cholesterol (15 mg/liter) vernichtete die Wachstumverhinderung jedoch nicht die Reproduktion. Fluorodeoxyuridine und Bromodeoxyuridine verhinderten Wachstum und Oosporenbildung. Deoxyadenosine hatte keine Wirkung. Diese Versuche zeigen, daß die metabolischen Prozesse, die in der Synthese des Myzeliums mitwirken, wesentlich verschieden von den Prozessen sind, die in Sexual-reproduktion mitwirken, da sie verschiedentlich von Sterols, Antibiotiks und von den Thymidine-analogen beeinflußt worden sind.

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Contribution No. 26 from the Botany Section, The Department of Biology.     

Engineering Grain Boundaries in Cu2ZnSnSe4 for Better Cell Performance: A First‐Principle Study

Through first‐principle density functional theory (DFT) calculations, the atomic structure and electronic properties of intrinsic and passivated Σ3 (114) grain boundaries (GBs) in Cu₂ZnSnSe₄ (CZTSe) are studied. Intrinsic GBs in CZTSe create localized deep states within the band gap and thus act as Shockley‐Read‐Hall recombination centers, which are detrimental to cell performance. Defects, such as Zn_Sn (Zn atoms on Sn sites), Na⁺_i (interstitial Na ions), and O_Se (O atoms on Se sites), prefer to segregate into GBs in CZTSe. The segregation of these defects at GBs exhibit two beneficial effects: 1) eliminating the deep gap states via wrong bonds breaking or weakening at GBs, making GBs electrically benign; and 2) creating hole barriers and electron sinkers, promoting effective charge separation at GBs. The results suggest a unique chemical approach for engineering GBs in CZTSe to achieve improved cell performance.     

Stock differentiation of the greater lizardfish Saurida tumbil (Teleostei: Synodontidae) collected along the western coast of the Arabian Gulf and Sea of Oman using meristic characters

Meristic variation among stocks of greater lizardfish Saurida tumbil through the western coasts of the Arabian Gulf and Sea of Oman was examined using meristic characters. Statistical analysis of meristic traits proposed that there is constrained migration of populations of greater lizardfish along the western coast of the Arabian Gulf and Sea of Oman. Overlapping of the two samples from the northern part of the Arabian Gulf (Iraq-Kuwait waters), three samples from the middle region of the Arabian Gulf (Bahrain-Qatar-Saudi Arabia) and two samples from the southern part of the Arabian Gulf/Sea of Oman (United Arab Emirates–Sultanate of Oman) suggested that there are three self-recruiting populations in the studied area. Inspection of the role of each meristic trait variable to Canonical discriminant analysis showed that changes among samples appeared to be linked with the pattern of distribution of water temperature and configuration of current in both the Arabian Gulf and Sea of Oman areas.