Nutrient losses after clearfelling in Beddgelert Forest: a comparison of the effects of conventional and whole-tree harvest on soil water chemistry

The effects of conventional, bole only harvesting (CH) and whole-treeharvesting (WTH) on major inorganic nutrient concentrations(K, NO₃-N, NH₄-N, PO₄-P and Ca) in soil water are describedfrom Beddgelert forest in North Wales. Monitoring of nutrientleaching losses, and the timing thereof, from brash throughthe soil and into streams draining the CH areas allowed assessmentsto be made of the value of brash as a nutrient source for secondrotation crops. Most of the K (around 100 kg ha^–1) and one-third of theP (10 out of 30 kg ha^–1) leached out of the brash lyingon the CH plots within one year of felling. A pulse of K passedthrough the soil profile, but less than half this K reachedthe streams. In contrast, the P was immobilized in the soil.The lack of brash resulted in the absence of K and P pulseson the WTH plots. On the CH plots, brash was a net sink forinorganic-N for 3 years after felling. However, in both CH andWTH, a pulse of nitrate was observed in the soil and also instreams draining CH areas. The source of this nitrate may havebeen death of fine tree roots, followed by rapid mineralizationand nitrification. Calculation of a nutrient budget for a complete crop rotationindicates that P and Ca losses in harvested material are likelyto result in long-term depletion of these elements, and thatthe effects will be significantly more severe if WTH is practised.     

Lipids of Ankistrodesmus braunii

Ankistrodesmus braunii wasgrown to stationary phase on a chemically defined medium and its cellular lipids were analyzed. The lipid content was found to vary from 18 to 73 percent of dry weight for cultures of different age and method of analysis. The pigments of the nonsaponifiable fraction were separated by adsorption chromatography and counter-current extraction and tentatively identified. The fatty acid fraction was converted to the corresponding methyl esters and analyzed by gas chromatography. The principal fatty acids present were: palmitic, oleic, and linolenic acids. Traces were detected of caprylic, capric, lauric, and palmitoleic acids.     

Pregnancy-related diabetes mellitus in two dogs

CASE SUMMARIES: Two cases of diabetes mellitus occurring in bitches in association with pregnancy are reported. In the first case, a bitch with suspected acromegaly developed diabetes mellitus within 2 weeks of the due date. Despite insulin therapy, euglycaemia was not achieved. Tw o live, small pups were delivered by elective Caesarean section but died within 2 days. Signs consistent with acromegaly resolved but diabetes mellitus was permanent in the bitch. In the second case, diabetic ketosis with severe gastrointestinal disease was diagnosed 2 days after Caesarean section was performed due to dystocia. The pups delivered all died within 5 days. The bitch recovered fully from diabetes mellitus within 2 weeks and has remained euglycaemic without insulin for a period of at least 18 months.

CLINICAL RELEVANCE: These two cases demonstrate that diabetes mellitus can occur in association with pregnancy in dogs, that diabetic ketosis can occur during transient diabetes mellitus in dogs, and suggest that acromegaly may occur during pregnancy-related dioestrus in dogs. The scarcity of previous reports of this nature, however, suggests that such cases are unusual.

Lack of prompt resolution of hyperglycaemia may result in secondary diabetes mellitus becoming permanent. Management should focus on immediate insulin therapy or ovariohysterectomy to minimise this risk. Even mild hyperglycaemia should not be ignored during pregnancy. The insulin antagonistic effects of pregnancy, stressful illness, surgery and dystocia can be enough to result in diabetic ketosis in the absence of permanent insulin deficiency. Maternal hyperglycaemia may contribute to adverse fetal outcomes in dogs but further study is required regarding the nature of the risk.     

Horizontal and vertical movements of juvenile bluefin tuna (Thunnus orientalis) in relation to seasons and oceanographic conditions in the eastern Pacific Ocean

Electronically tagged juvenile Pacific bluefin, Thunnus orientalis, were released off Baja California in the summer of 2002. Time‐series data were analyzed for 18 fish that provided a record of 380 ± 120 days (mean ± SD) of ambient water and peritoneal cavity temperatures at 120 s intervals. Geolocations of tagged fish were estimated based on light‐based longitude and sea surface temperature‐based latitude algorithms. The horizontal and vertical movement patterns of Pacific bluefin were examined in relation to oceanographic conditions and the occurrence of feeding events inferred from thermal fluctuations in the peritoneal cavity. In summer, fish were located primarily in the Southern California Bight and over the continental shelf of Baja California, where juvenile Pacific bluefin use the top of the water column, undertaking occasional, brief forays to depths below the thermocline. In autumn, bluefin migrated north to the waters off the Central California coast when thermal fronts form as the result of weakened equatorward wind stress. An examination of ambient and peritoneal temperatures revealed that bluefin tuna fed during this period along the frontal boundaries. In mid‐winter, the bluefin returned to the Southern California Bight possibly because of strong downwelling and depletion of prey species off the Central California waters. The elevation of the mean peritoneal cavity temperature above the mean ambient water temperature increased as ambient water temperature decreased. The ability of juvenile bluefin tuna to maintain a thermal excess of 10°C occurred at ambient temperatures of 11–14°C when the fish were off the Central California coast. This suggests that the bluefin maintain peritoneal temperature by increasing heat conservation and possibly by increasing internal heat production when in cooler waters. For all of the Pacific bluefin tuna, there was a significant correlation between their mean nighttime depth and the visible disk area of the moon.     

Detection of Water Buffalo Sex Chromosomes in Spermatozoa by Fluorescence in situ Hybridization

In order to identify X‐ and Y‐bearing spermatozoa in water buffalo by fluorescence in situ hybridization (FISH), some available probes of closely related species were examined. An X‐ and Y‐specific probe set, made from flow sorted yak chromosomes, labelled in somatic metaphases of water buffalo the whole X and Y, respectively, except their centromere regions. A cattle Y‐chromosome repeat sequence (BC1.2) showed strong signal on the telomere region of the buffalo Y‐chromosome, demonstrating the evolutionary conservation of this locus in water buffalo. In hybridization experiments with spermatozoa from five buffaloes, the yak X‐Y paint set demonstrated clear signals in more than 92% (46.8% X and 45.8% Y) of the cells. Using the cattle Y‐chromosome specific BC1.2 probe, clear hybridization signal was detected in more than 48% of the cells. Statistical analysis showed that there was no significant difference between bulls or from the expected 50 : 50 ratio of X‐ and Y‐bearing cells. The probes presented here are reliable to assess separation of X‐ and Y‐bearing spermatozoa.     

腹腔注射N-甲基-D-天冬氨酸对母鼠发情率、早期胚胎及胚子数的影响

为研究腹腔注射N-甲基-D-天冬氨酸(NMDA)对母鼠发情率和早期胚胎及胚子数的影响,试验选取40只昆明小鼠[(26±1.37)g],随机分为对照组和试验组(每组各20只),对照组腹腔注射0.2mL生理盐水,试验组腹腔注射0.2mLNMDA溶液,采用棉签蘸取母鼠阴道黏液,涂片后用苏木精(HE)染色,判定母鼠发情情况。随后在发情母鼠与公鼠合笼后第3天,每组随机取10只颈椎脱臼法处死小鼠,冲胚后在体视镜下捡胚观察胚胎个数;第9天处死剩余小鼠,取出子宫统计胚子数。试验结果显示,腹腔注射NMDA试验组母鼠发情率、胚胎数和胚子数分别比对照组提高28.57%、18.18%和12.94%。该试验表明腹腔注射NMDA可促进母鼠的发情,提高早期胚胎和胚子数,为NMDA在动物繁殖中的应用提供了理论基础。     

Successful Vitrification of In vivo Embryos Collected from Superovulated Japanese Black Cattle (Wagyu)

The aim of this study was to determine whether vitrification is an effective method when used for Japanese Black Cattle (Wagyu) in vivo‐derived embryos, collected following a superovulation treatment and embryo transfer (MOET) programme. In vivo‐derived morula and blastocysts collected on day 7 after artificial insemination, were vitrified using a modified droplet vitrification (MDV) procedure and subsequently warmed for transfer (ET) into synchronized recipients. Fresh embryos, and embryos cryopreserved using a standardized slow freezing procedure (direct thaw/direct transfer, DT) served as ET controls. Two different follicle‐stimulating hormone (FSH) sources, Folltropin^® Canada (FSH BAH, 24 donors) and a brand prepared by the Chinese Academy of Science (FSH CAS, 16 donors), were compared in a series of superovulation outcomes following well‐established FSH administration protocols. Following data analysis, the total number of ovulations recorded at the time of embryo flushing (10.5 vs 8.5; p = 0.28) and the total number of transferable embryos (6.2 vs 5.1; p = 0.52) were similar between the two FSH sources. ET for MDV (39.7%, n = 78), DT (35.2%, n = 71) and fresh controls (47.1%, n = 34) resulted in similar pregnancy rates (p > 0.05). When MDV was used, a higher pregnancy rate (42.6%) resulted from the transfer of vitrified morulae, when compared to the DT counterparts (24.3%), (p = 0.05). Transfer of vitrified morulae resulted also in higher pregnancy rate, when compared to the transfer of vitrified blastocysts (42.6% vs. 29.4%; p < 0.05). Transfer of DT blastocysts resulted in higher pregnancy rate than morulae, similarly cryopreserved (47.1% vs. 24.3%, p < 0.05). In conclusion, MDV is an effective alternative methodology for cryopreservation of in vivo‐derived embryos. This study gives also indication that, compared to vitrified blastocysts, MDV of morula stage embryos results in higher pregnancy rates following warming and transfer into synchronized recipients.