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Milk protein synthesis in the mammary gland involves expression of six major milk proteins' genes whose nutritional regulation remains poorly defined. In this study, the effect of long-term under- and overfeeding on the expression of as1-casein: CSN1S1, as2-casein: CSN1S2, β-casein: CSN2, κ-casein: CSN3, α-lactalbumin: LALBA and β-lactoglobulin: BLG gene in goat mammary tissue (MT) was examined. Twenty-four lactating dairy goat, at 90-98 days in milk, were divided into three homogenous subgroups and fed the same ration, for 60 days, in quantities which met 70% (underfeeding), 100% (control) and 130% (overfeeding) of their energy and crude protein requirements. The results showed a significant decrease in mRNA of CSN1S2, CSN2, CSN3 and LALBA genes in the MT of underfed goats compared with the overfed and on the CSN1S1 and BLG gene expressions in the MT of underfed goats compared with the respective control and overfed. CSN2 was the most abundant transcript in goat MT relative to the other milk proteins' genes. Significantly positive correlations were observed between the mRNA levels of caseins' and BLG genes with the milk yield. Moreover, a significant correlation was found between the mRNA levels of CSN1S2 with the milk protein, lactose content and lactose yield and also between the LALBA gene expression with the lactose content and lactose yield respectively. In conclusion, the feeding level and consequently the nutrients availability affected the milk lactose content, protein and lactose yield as well as the milk volume by altering the CSN1S1, CSN1S2, CSN2, CSN3, LALBA and BLG gene expression involved in their metabolic pathways.

In the laboratory under LD 12:12 h-conditions, mating behavior of D. oleae takes place during the last 3–4 h of the photophase and terminates abruptly with the onset of darkness. Mating behavior is independent of low light intensities, nor need it be graded. The acoustical components of sexual activity include ♂-courtship and strong wing-beat frequencies during copulatory attemps and pursuits in flight. Mating activity is a circadian event and in constant whitelight or redlight (600–700 nm) a free-running rhythm with τ < 24 h develops and persists for several cycles. However, the quantity of mating activity decreases rapidly. Zusammenfassung Uber den Begattungsrhythmus bei der Olivenfliege, Dacus oleae Gmel. Unter LD 12: 12 h-Bedingungen konzentriert sich das Begattungsverhalten von Dacus oleae auf die letzten 3–4 h der Lichtphase. Geringe oder graduell abnehmende Lichtintensitaten sind keine Voraussetzungen fur den Ablauf des Verhaltens. Akustische Verhaltensweisen im Rahmen der Sexualaktivitat umfassen die ♂-Balz, sowie verstarkte Flugelschlagfrequenzen wahrend der Kopulationsversuche und Verfolgungsfluge. Das Begattungsverhalten ist circadian gesteuert und hat unter konstanten Dauerlicht- und Rotlichtbedingungen eine Periode τ < 24 h. Der Rhythmus uberdauert mehrere Zyklen, aber die Anzahl der Begattungen nimmt rasch ab.

Developmental analysis of the tyrosine protein phosphorylation levels in larval integument and partial characterization of the endogenous protein tyrosine kinase activity (PTK) in Ceratitis capitata are described in this study. Larval integument contains high levels of PTK activity at the early stages of the third instar, which progressively declines to low levels in the white pupal stage. An integumental 90-kDa polypeptide was identified to have prominent endogenous PTK activity and follow a similar developmental pattern. The major integumental phosphotyrosine-containing polypeptides have apparent molecular weights of 30, 41, 44, 46, and 54 kDa, respectively. Polypeptides with molecular weights of 62 and 73 kDa were identified as Ser/Thr-containing phosphoproteins and were shown to exhibit high levels of phosphorylation at the middle stage of larval development. These differences are likely to be due to the higher activation state of the protein tyrosine kinase(s) at the early stages of larval development. Arch. Insect Biochem. Physiol. 50:9–20, 2002. © 2002 Wiley-Liss, Inc.

It is well known that activated prophenoloxidase (proPO) plays an important role in cuticular melanization and sclerotization. In addition, studies dealing with immune response of insects suggest that phenoloxidase (PO) is also critical in the defense reactions of insects against invaders. proPO is activated by elicitors derived from microbial cell wall components such as peptidoglycan, beta-1,3-glucan, and lipopolysaccharide (LPS). According to our recent studies we proposed a model clarifying the role of PO in both cellular and humoral immune responses. LPS triggers Ceratitis capitata hemocytes via induced protein tyrosine phosphorylation to release biologically active molecules, including p47 and proPO-activators. Furthermore, hemocytes in response to LPS facilitate clearance of LPS from the hemocoel of medfly. The effector molecules involved in the LPS clearance are hemocyte surface-associated p47 (mp47), soluble p47 (sp47), activated proPO, and tyrosine. A similar LPS clearance system in the integument of medfly in vitro was also demonstrated. According to our data, the proposed mechanism for LPS clearance from hemocoel and from integument is the crosslinking of LPS to p47 or certain integumental proteins via the intermediacy of reactive tyrosine derivatives generated by PO activity, as is the case for cuticular protein-chitin crosslinks during sclerotization. We also demonstrated that metabolites of the eumelanin biosynthesis and not melanin itself or N-acetyldopamine (NADA), the key precursor of sclerotizing agent, were necessary for the immune responses by hemocytes and integument.

Larval Ceratitis capitata phenoloxidases (POs) from hemocytes, serum, integument, and fat body were analyzed. Two types of PO were recorded: the tyrosinase type found in hemocytes, serum, integument, and fat body and the laccase type found in integument. Tyrosinase from all larval tissues and integumental laccase as well, showed similarity in molecular weight (93 KDa), activation by Escherichia coli at 5 mM Ca2+, and reactivity to antibodies raised against serum tyrosinase. However, the enzymes differed with respect to their glycosylation and adhesiveness. The serum and integumental enzyme forms contain concanavalin A reacting material, whereas hemocyte and integumental tyrosinase(s) are adhesive. These differences in enzyme forms, although not influencing their substrate specificity, seem to give advantages to performing their function, i.e., the adhesive enzyme form facilitates the adherence to E. coli cell wall and hemocyte surface (unpublished data) while the glycosylated form facilitated the secretion into serum. © 1994 Wiley-Liss, Inc.