The trans Golgi network: sorting at the exit site of the Golgi complex

The Golgi complex is a series of membrane compartments through which proteins destined for the plasma membrane, secretory vesicles, and lysosomes move sequentially. A model is proposed whereby these three different classes of proteins are sorted into different vesicles in the last Golgi compartment, the trans Golgi network. This compartment corresponds to a tubular reticulum on the trans side of the Golgi stack, previously called Golgi endoplasmic reticulum lysosomes (GERL).     

Efficient inhibition of the Alzheimer's disease beta-secretase by membrane targeting

beta-Secretase plays a critical role in beta-amyloid formation and thus provides a therapeutic target for Alzheimer's disease. Inhibitor design has usually focused on active-site binding, neglecting the subcellular localization of active enzyme. We have addressed this issue by synthesizing a membrane-anchored version of a beta-secretase transition-state inhibitor by linking it to a sterol moiety. Thus, we targeted the inhibitor to active beta-secretase found in endosomes and also reduced the dimensionality of the inhibitor, increasing its local membrane concentration. This inhibitor reduced enzyme activity much more efficiently than did the free inhibitor in cultured cells and in vivo. In addition to effectively targeting beta-secretase, this strategy could also be used in designing potent drugs against other membrane protein targets.     

Gametogenesis and breeding of Ostrea edulis on the west coast of Ireland

Gametogenesis, spawning and larval production of the European flat oyster Ostrea edulis L. were studied in sublittoral beds in Ballinakill Harbour and Kilkieran Bay, Co. Galway, from April 1977 to November 1978 and from November 1978 to May 1980 respectively. Histol ogical preparations of gonads and percentages of oysters brooding larvae were used to monitor breeding.Maturation began in March/April with ripe gametes appearing in some oysters in mid-May. Incubating oysters were observed from mid-June to August/September. Spent oysters were numerous in September. Gametogenesis was at a minimum from October to February depending on the year of study. Ripeness as measured by four different parameters was observed to peak around 29 June 1977 and 4 July 1978 in Ballinakill Harbour, and on 10 July 1979 in Kilkieran Bay. The onset of maximum ripeness in both populations could be predicted using the formula:

$\text{D=}\text{∑}\text{i=1}\text{N}\text{(t}{}_{\mathrm{i}}\text{? t}{}_0$

where D is the thermal constant in degree-days, n = the number of days required to reach ripeness, t_i = temperature to which the oysters were exposed daily (°C) and t₀ is the developmental zero for gametogenesis. The mean thermal constant as calculated from the gametogenesis study was 554.52 ± 44.52 degree-days. Redevelopment of gametes began during late winter at mean seawater temperatures above approximately 7.0°C.     

Germination requirements of <Emphasis Type="Italic">Allanblackia parviflora</Emphasis> seeds and early growth of seedlings

Allanblackia parviflora A. Chev, is an indigenous fruit tree species that could be used in agroforestry systems with both environmental and economic benefits. The seed oil is of prime importance as a foreign exchange earner and is being developed as a rural based enterprise in many African countries notably Ghana, Nigeria, Cameroon and Tanzania. Methods for propagation and conservation of the species are therefore of prime importance. The seeds of the species are however difficult to germinate hindering its domestication process. Allanblackia parviflora seeds were collected from seven different populations in Ghana and were subjected to four different seed germination trials at the nursery of CSIR-Forestry Research Institute of Ghana at Fumesua, Kumasi. This was followed by studying the effect of stage of seed germination on establishment after potting. Intact seeds began germination at 7 months after sowing and at 24 months, significant (P < 0.001) variations were observed in the seed germination ability of 74 accessions. Mean seed germination ranged from 0 to 35%. Significant differences in seed germination percentages among populations (P < 0.001) and provenances (P < 0.05) were also observed. Removal of seed coat significantly (P < 0.001) enhanced seed germination. Germination percentages of seeds with seed coat removed ranged from 6 to 43% while seed germination percentages for intact seeds were less or equal to 3%. Incubation of seeds with seed coat removed in polythene bags gave an added advantage. Seeds with seed coat removed and kept in polythene bags started germinating from 2 weeks and within 10 months, 75 and 68% germination were obtained for plane and black polythene bags, respectively. Removal of germinants and potting when shoot length was at least 1 cm gave significantly higher growth (P < 0.001 for shoot height, P < 0.05 for stem diameter, P < 0.001 for number of leaves produced) compared to when only radicle had emerged. It became evident in this study that seeds should be classified as fully germinated only when shoots begin to grow.     

Reproductive performance in South Australian dairy herds

SUMMARY Herd breeding records (161) were examined from a random 10% sample of dairy farms (96) in South Australia with more than 40 cows and suitable breeding records for 1988 and/or 1989. Of these farms, 53 (55.2%) had a year-round calving pattern, 42 (43.8%) claimed to be seasonal and one was changing from a year-round to a seasonal pattern. Only 14.6% of farmers observed oestrous behaviour outside milking times and 18.8% used tailpaint. Overall, the average proportion of unobserved heats was estimated to be 32%. Artificial insemination (AI) was carried out on 85.4% of farms (16.7% used AI alone and 68.7% also used bulls) of which 32.9% used commercial technicians and 67.1% were do-it-yourself operators. Overall, the average 30-day submission rate was 59.9% and the average 49-day non-return to service rate was 58.9%. Investigation into the probable causes of suboptimal reproductive performance gave a tentative diagnosis of inefficient oestrous detection, deferral of service, inadequate nutrition, poor AI technique, insufficient bulls, and venereal/other diseases in 69.1, 32.1, 27.2, 28.4, 13.6 and 7.4% of records, respectively.     

The Presence of Borrelia miyamotoi,A Relapsing Fever Spirochaete,in Questing Ixodes ricinus in Belgium and in The Netherlands

Borrelia miyamotoi is a tick‐borne bacterium that may cause relapsing fever in humans. As this pathogen has been discovered in Europe only recently, only little is known about its local impact on human health and its spatial distribution. In this study, we show the results of PCR screenings for B. miyamotoi in flagged Ixodes ricinus from Belgium and the Netherlands. B. miyamotoi was detected in nine of thirteen, and three of five locations from the Netherlands and Belgium, respectively. These outcomes indicate that B. miyamotoi is more spread than previously thought. The mean infection rate B. miyamotoi was 1.14% for Belgium and 3.84% for the Netherlands.     

Serratospiculosis in a New Zealand Falcon (Falco novaeseelandiae)

CASE HISTORY: An adult New Zealand falcon was presented with metacarpal fractures in the left wing.

CLINICAL FINDINGS: In addition to the fractures, radiographs revealed an area of opacity in the air sacs. A few days after hospitalisation and initiation of treatment of the fractures, the bird developed signs of respiratory disease; the area of opacity was found to have increased in size and density. Treatment with antibiotics and nebulisation was commenced; the bird initially responded but respiratory signs subsequently worsened and the bird died. At necropsy, air sacculitis and bronchopneumonia were associated with numerous nematodes in the air sacs, which were morphologically consistent with Serratospiculum guttatum.

DIAGNOSIS: Serratospiculosis

CLINICAL RELEVANCE: The discovery of this parasite and the associated disease for the first time in New Zealand indicates that it should be considered in the differential diagnosis of respiratory disease in falcons and possibly other raptors in New Zealand.     

Biological control of Otiorrhynchus sulcatus with Heterorhabditid nematodes in the glasshouse

AHeterorhabditis species, found in dead larvae ofOtiorrhynchus sulcatus, was tested for its efficacy as a biological control agent of this insect in glasshouse experiments. In a preliminary test all weevil larvae were killed in pots with primula, 88% in strawberry and 50% in cyclamen. In a second test with strawberry plants good results were obtained when the nematodes were applied about the hatching time of the weevil eggs. At a dosage of 100 nematodes per cm² of soil area, 90–97% of the larvae were killed and 90% of the plants remained undamaged. A dosage of 50 nematodes per cm² produced roughly the same level of larval mortality, but left 30% of the plants damaged. Both early and late application of nematodes protected the plants insufficiently, because too many larvae survived. In a third test with strawberry, cyclamen and primula, soil treatment with 50 and 100 nematodes per cm² gave comparable results at both application times, i.e. one and three weeks after hatching of the weevil eggs. In strawberry 100% of the larvae were killed and all plants remained in good condition. Also in cyclamen nearly all larvae were killed and the plants remained in good condition, although the root systems had, less fine roots in comparison with control plants without insects. In primula 4–12% of the weevil larvae survived, whereas up to 20% of the plants died, indicating that soil structure, soil moisture, and condition of the plants have an important impact on the control results. A dosage of 25 nematodes per cm² appeared to be too low in all cases. The results of these experiments open new perspectives for control of the black vine weevil in glasshouses.Samenvatting Een inheemse, nematode van het geslachtHeterorhabditis werd door middel van potproeven in kassen getoetst op zijn werkzaamheid als biologisch bestrijdingsmiddel tegen larven van de gegroefde lapsnuitkever,Otiorrhynchus sulcatus. In een oriënterende proef werden in potten met primula's alle keverlarven gedood, bij aardbeiplanten werden 88% gedood en bij cyclamen 50%. In een tweede proef met alleen aardbeiplanten werden goede resultaten verkregen als de aaltjes werden toegediend in de periode dat de kevereieren uitkwamen. Bij een dosering van 100 aaltjes per cm² grondoppervlak werd 90–97% van de keverlarven gedood en bleef 90% van de planten onbeschadigd. Bij een dosering van 50 aaltjes per cm² was de doding van de keverlarven weliswaar vrijwel hetzelfde, maar de schade aan de planten was te groot; 30% van de planten ging dood. Ook bij een eerder of later bestrijdingstijdstip was de schade aan de planten aanzienlijk en was de doding van de keverlarven onvoldoende. In een derde proef werd in zowel aardbei als in cyclamen vrijwel 100% van de keverlarven gedood bij een dosering van zowel 50 als 100 aaltjes per cm² en op beide bestrijdingstijdstippen, te weten toen de keverlarven circa 1 en 3 weken oud waren. Alle aardbeiplanten en cyclamen bleven in goede staat, hoewel bij cyclamen het aantal fijne wortels minder was dan bij de controle planten zonder keverlarven. De resultaten met primula's waren in deze proef iets minder goed. Het percentage overlevende keverlarven variëerde van 4 tot 12, terwijl tot 20% van de planten dood ging. Een dosering van 25 aaltjes per cm² was in alle gevallen te laag. De resultaten van deze proeven bieden gunstige perspectieven voor toepassing van dit aaltje bij de bestrijding van de gegroefde lapsnuitkever in kassen.