Gas chromatography for detection of citrus infestation by fruit fly larvae (Diptera: Tephritidae)

Tephritid fruit flies are serious economic pests worldwide. As larvae, they feed and develop within the pulp of host fruits, making infestation difficult to detect by visual inspection. At U.S. ports of entry, incoming produce shipments are checked for infestation by manually cutting open a small sample of fruit and searching for tephritid larvae. Consequently, there is a need for more sensitive, high-throughput screening methods. This study evaluated gas chromatography (GC) as a potential technology for improved detection of hidden infestation. Grapefruits (Citrus × paradisi Macfad.) infested with immature stages of the Caribbean fruit fly Anastrepha suspensa (Loew) (Diptera: Tephritidae) were examined to determine if infested fruit emitted a chemical profile distinct from that of non-infested fruit. Peaks identified by GC analysis were grouped into three classes. Chemicals detected in similar quantities in all samples, or slightly elevated in infested samples, were regarded as non-diagnostic background volatiles. Chemicals highly elevated after oviposition, during the last instar exit stage, and in experimentally-pierced fruit were interpreted to be indicators of citrus peel injury, and included d-limonene and β-ocimene. Chemicals elevated exclusively in the larval infestation stages were considered indicators of feeding damage and potentially diagnostic of infestation, and included hexyl butanoate and an unidentified compound. The peaks associated with injury and feeding were also detectable with a portable ultra-fast GC analyzer that required less than 80 s per sample. Further studies will investigate the potential application of these results for development of a rapid, non-destructive screening method for detection of tephritid infestation.     

Distribution and abundance of overwintering Calanus finmarchicus in the Faroe–Shetland Channel

The distribution and abundance of overwintering Calanus finmarchicus in the Faroe–Shetland Channel was studied during December 1994 and January 1995. Maximum abundance of animals in the Channel was approximately 50 000 m⁻², with a peak concentration of 627 m⁻³ at a depth of 930 m. Copepodite stages IV and V accounted for > 98% of the population. A clear association was found between the horizontal and vertical distribution of animals and the Arctic water masses in the bottom of the Faroe–Shetland Channel. The Wyville–Thomson Ridge formed a barrier to the southern distribution of Arctic waters and the abundance of overwintering C. finmarchicus was 25 times lower to the south of the Ridge than to the north. Spatial variability in lipid content and composition indicated that overwintering C. finmarchicus in the southern Norwegian Sea were in poorer condition with respect to wax ester content, and in a more advanced state of emergence from overwintering, than the animals within the Channel. The overwintering stock in the Channel probably originated from the Norwegian Sea or from north of the Faroe Islands. The Faroe–Shetland Channel is an important source of animals advected into the northern North Sea in the spring (March/April). The population abundance in the Faroe–Shetland Channel was estimated to be 4.5 × 10¹⁴ individuals, which is more than adequate to account for the mean concentration of adult stages observed in the northern North Sea in April.     

Seasonal changes in respiration rates of copepodite stage V Calanus finmarchicus (Gunnerus)

Copepodite stage V Calanus finmarchicus were collected at locations on the continental shelf north of Scotland, in the Faroe–Shetland Channel and west of Ireland on six occasions covering winter, spring and summer from October 1993 to June 1995. Oxygen consumption by the overwintering and active spring/summer population of animals was determined at temperatures close to in situ temperatures. Laboratory measurements of oxygen consumption were also made at standardized temperatures (0°C, 5°C, 7°C and 12.5°C) to determine the sensitivity of animals to temperature change in the different seasons. Rates of oxygen consumption were very low (7–30 μmol O₂ gC⁻¹ h⁻¹) at in situ temperatures during the winter and early spring and significantly higher (105–219 μmol O₂ gC⁻¹ h⁻¹) for the active surface population in May and June. Animals collected from the overwintering population showed no significant response to changes in temperature. Due to the low respiration rates, the calculated rate of decrease in carbon content in diapausing copepodite stage CV was very low (approximately 0.250 μgC day⁻¹). The respiration rates were used to construct a model to estimate survival of the animals with an initial carbon content equivalent to that expected of animals in October. The results showed that in order to survive during winter and have enough energy for moulting and migration to the surface in the spring, these animals have to live at temperatures close to 0°C and be in a diapause state.     

A model of the spring migration into the North Sea by Calanus finmarchicus overwintering off the Scottish continental shelf

A particle tracking model was used to investigate the annual spring invasion of the North Sea by Calanus finmarchicus copepodites which overwinter in deep water off the Scottish continental shelf. Flow fields generated by a hydrodynamic model (HDM) were used to simulate the advection of zero drag particles representing the copepods. Particles were released simultaneously from a regular lattice of start positions at a given depth ( D ₁), and ascended at a fixed rate ( dD/dt ) until they reached a final depth ( D ₂) in the surface layers. The proportion of particles reaching target areas in the northern North Sea was relatively insensitive to a moderate degree of variation (±20%) around chosen default values of the vertical migration parameters ( D ₁, D ₂ and dD/dt ), derived from field data. The inclusion of horizontal diffusion velocities and diel vertical migration in surface layers did not significantly affect the results. Sensitivity to wind direction was investigated by applying flow fields from HDM runs with different wind forcing scenarios. For the default vertical migration parameters, only north-westerly winds resulted in particles entering the North Sea from release locations north of the Iceland–Scotland Ridge, where dense aggregations of overwintering copepods were encountered during field surveys. The particle tracking model predicted that the major routes for the spring Calanus invasion into the North Sea were the East of Shetland Atlantic Inflow and the Norwegian Trench Atlantic Inflow, which agreed with seasonal trends observed in Continuous Plankton Recorder data. Overall, despite its relative simplicity, particle tracking was confirmed as a robust tool to explore the causal mechanisms behind the annual invasion of the North Sea by C. finmarchicus emerging from diapause in the deep waters off the Scottish continental shelf.     

Expression and localization of BCRP,MRP1 and MRP2 in intestines,liver and kidney in horse

Tydén, E., Bj?rnstr?m, H., Tjälve, H., Larsson, P. Expression and localization of BCRP, MRP1 and MRP2 in intestines, liver and kidney in horse. J. vet. Pharmacol. Therap. doi: 10.1111/j.1365‐2885.2009.01140.x. The gene and protein expression and the cellular localization of the ABC transport proteins breast cancer resistance protein (BCRP), multidrug resistance‐associated protein 1 (MRP1) and multidrug resistance‐associated protein 2 (MRP2) have been examined in the intestines, liver and kidney in horse. High gene and protein expression of BCRP and MRP2 were found in the small intestines, with cellular localization in the apical membranes of the enterocytes. In the liver, MRP2 was present in the bile canalicular membranes of the hepatocytes, whereas BCRP was localized in the cytoplasm of hepatocytes in the peripheral parts of the liver lobuli. In the kidney both BCRP and MRP2 were predominantly present in the distal tubuli and in the loops of Henle. In most tissues, the gene and protein expression of MRP1 were much lower than for BCRP and MRP2. Immunostaining of MRP1 was detectable only in the intestines and with localization in the cytoplasm of enterocytes in the caecum and colon and in the cells of serous acini of Brunner’s glands in the duodenum and the upper jejunum. The latter cells were also stained for BCRP, but not for MRP2. Many drugs used in horse are substrates for one or more of the ABC transport proteins. These transporters may therefore have important functions for oral bioavailability, distribution and excretion of substrate compounds in horse.     

Leukotrienes Affect Secretory Function of Ovarian Cells In Vitro*

The aim of this study was to determine which cells are the source of production and target for leukotriene (LTs) action within the bovine ovary. Luteal (CL, days 14–16 of the oestrous cycle), steroidogenic cells (LSC) and endothelial cells (LEC) of the bovine corpus luteum (CL), and granulosa cells (GC) were isolated enzymatically, cultured in a monolayer and incubated with LTC₄, LTB₄, Azelastine (an antagonist of LTC₄) or Dapsone (an antagonist of LTB₄). Then cells were collected for determination of mRNA expression for LT receptors (LTRs) and 5‐lipoxygenase (5‐LO) by real time RT‐PCR, and media were collected for determination of prostaglandin (PG)E₂, F_2α, progesterone (P4; LSC only), endothelin‐1 (ET‐1; LEC only) and 17‐β oestradiol (E2; GC only). The greatest mRNA expression for LTR‐II and 5‐LO were found in LEC, whereas LTR‐I mRNA expression did not differ among cell types. The level of PGE₂ increased after LTs treatment in each type of ovarian cell, excluding LTC₄ treatment in LEC. The secretion of PGF_2α was also increased by LTs, but decreased after LTB₄ treatment of LSC. In GC cultures, both LTs stimulated E2 secretion; in LEC cultures, LTB₄ stimulated whereas LTC₄ inhibited P4 secretion; in LEC cultures, LTC₄ stimulated but LTB₄ inhibited ET‐1 secretion. The results show that LTs are produced locally and are involved in PGs production/secretion in all examined cells (LSC, LEC and GC) of bovine ovary. Leukotriene treatment modulate secretion of E2, by GC, P4 by LSC and ET‐1 by LEC, which indicates that LTs are involved in regulation of ovarian secretory functions.