Lhx2 selector activity specifies cortical identity and suppresses hippocampal organizer fate

The earliest step in creating the cerebral cortex is the specification of neuroepithelium to a cortical fate. Using mouse genetic mosaics and timed inactivations, we demonstrated that Lhx2 acts as a classic selector gene and essential intrinsic determinant of cortical identity. Lhx2 selector activity is restricted to an early critical period when stem cells comprise the cortical neuroepithelium, where it acts cell-autonomously to specify cortical identity and suppress alternative fates in a spatially dependent manner. Laterally, Lhx2 null cells adopt antihem identity, whereas medially they become cortical hem cells, which can induce and organize ectopic hippocampal fields. In addition to providing functional evidence for Lhx2 selector activity, these findings show that the cortical hem is a hippocampal organizer.     

A cytokinin perception mutant colonized by Rhizobium in the absence of nodule organogenesis

In legumes, Nod-factor signaling by rhizobia initiates the development of the nitrogen-fixing nodule symbiosis, but the direct cell division stimulus that brings about nodule primordia inception in the root cortex remains obscure. We showed that Lotus japonicus plants homozygous for a mutation in the HYPERINFECTED 1 (HIT1) locus exhibit abundant infection-thread formation but fail to initiate timely cortical cell divisions in response to rhizobial signaling. We demonstrated that the corresponding gene encodes a cytokinin receptor that is required for the activation of the nodule inception regulator Nin and nodule organogenesis.     

The effect of phosphorus fertilization on the chemical quality of Katahdin potatoes

The influence of phosphorus fertilization on the content of ascorbic acid, lipids, total nitrogen, protein, and non-protein nitrogen of Katahdin potatoes was investigated. Phosphorus in the form of mono ammonium phosphate was applied at rates of 0, 56, 112, and 168 Kg/ha (0, 50, 100, and 150 lb/acre). Ascorbic acid, total nitrogen, protein and non-protein nitrogen content were significantly increased (p<.01) and the phospholipid content was significantly reduced (p<.01) by phosphorus application.     

Assessment of Nitrogen Leaching at ICP-Waters Sites (Europe and North America)

The International Cooperative Programme on Assessment and Monitoring of Acidification of Rivers and Lakes (ICP-Waters) is designed to assess the degree and geographical extent of acidification of surface waters. During the last 20 years, international emission reduction measures in Europe and North America have resulted in a decrease in atmospheric S-deposition of up to 50%, while N-deposition has stayed almost constant. Empirical relationships between N-deposition and stages of nitrogen saturation are used to assess the importance of nitrogen leaching at the ICP-Waters sites in Europe and North America. There is a clear coherence between high N saturation stages and high N deposition loads and more than 50% of the analysed ICP Waters sites show a high degree of nitrogen saturation, defined as stages 2 or 3 in Stoddard's classification system. Significant leaching of inorganic N also occurs at most sites with deposition greater than 10 kg/ha/yr.     

Packed red blood cell transfusions in dogs with gastrointestinal hemorrhage: 55 cases (1999-2001)

Fifty-five dogs received packed red blood cell (PRBC) transfusions for gastrointestinal (GI) hemorrhage during a 26-month period (1999 to 2001), accounting for 11.7% of the PRBC transfusions in that time. Thirty-nine (61%) dogs had an intestinal pathology (primary or secondary) as the cause of GI hemorrhage, including intestinal masses, gastroenteritis, hepatic disease, and renal disease. Nonsteroidal and steroidal anti-inflammatory drug use was found frequently in dogs with GI hemorrhage. Sixteen (39%) dogs were identified as having immune-mediated thrombocytopenia (IMT) and associated GI hemorrhage. Dogs with IMT received more transfusions of PRBC than nonIMT dogs (P<0.03) and received a significantly larger total volume of PRBC (P<0.01) during hospitalization.     

Initial Experience with Norepinephrine Infusion in Hypotensive Critically III Foals

Seven critically ill foals that continued to be hypotensive despite fluid resuscitation and the infusion of dobutamine and/or dopamine were treated with an infusion of norepinephrine (noradrenaline). The norepinephrine was administered concurrently with dobutamine, and the combination therapy was titrated by use of indirect mean arterial pressure measurements. The highest dose of norepinephrine used was 1.5 mcg/kg/min. In six foals the administration of norepinephrine was associated with an increase in blood pressure. In one foal the mean arterial pressure did not increase in response to the doses of norepinephrine administered. All of the foals experienced an increase in urine output coincident with the start of the norepinephrine infusion. Three of the foal survived to hospital discharge.     

1,4-Dimethylnaphthalene treatment of seed potatoes affects tuber size distribution

1,4-DMN is a relatively new sprout inhibitor for use on maincrop and seed potatoes. Despite its registration as a “dormancy enhancer” for seed, relatively little is known about its effects on plant establishment and productivity. The main objective of this study was to evaluate the effects of 1,4-DMN on the productivity of seed potatoes. ‘Umatilla Russet’ (UR), ‘Ranger Russet’ (RR), and ‘Russet Burbank’ (RB) seed tubers were stored at 4, 7, and 9 C over three seasons to create 80-, 554- and 642-degree-day seed, and 1,4-DMN was applied to maintain dormancy several times during each season. 1,4-DMN residue levels at the end of storage were lower in seed aged at higher temperatures. Multiple applications of 1,4-DMN at higher-than-label rates were necessary to effectively inhibit sprouting of seed of all cultivars stored above 4 C. In field trials, depending on cultivar and year, 1,4-DMN either delayed plant emergence slightly or had no effect. 1,4-DMN increased stem numbers from RB and UR seed, but not from RR seed. 1,4-DMN reduced total tuber yields by 3.2 to 5.6 t ha^?1 (5% to 9%), and U.S. No. 1 tuber yields by 4.8 to 7.8 t ha^?1 (8% to 15%) in all cultivars, regardless of seed tuber age. 1,4-DMN also reduced the average tuber weight for all three cultivars and shifted the size distribution from larger (> 284 g) to smaller tubers. 1,4-DMN reduced the respective yields of > 397-g, 340-to 397-g, and 284-to 340-g tubers by 43%, 19%, and 18% for RR seed, 31%, 14%, and 11% for RB seed, and 40%, 47%, and 27% for UR seed. Conversely, depending on cultivar, yields of smaller tubers (≤170 g) were 11% to 38% higher from 1,4-DMN-treated seed. The shift in tuber size distribution for RR was accompanied by a 1,4-DMN-induced increase in tuber number per plant and per hectare. However, no such effects on tuber set occurred in RB and UR. Moreover, in most cases, the 1,4-DMN effects on yield and tuber size distribution were independent of seed age. Since the 1,4-DMN-induced shifts in tuber size distribution were greater than the reductions in total and U.S. No. 1 yields, 1,4-DMN may be a suitable treatment to reduce average tuber size and increase yield and uniformity of specific size classes of tubers to more closely match market requirements.     

Auxin Modulates Gibberellin-Induced Effects on Growth,Yield, and Raw Product Recovery for Frozen Processing in Potato (<Emphasis Type="Italic">Solanum tuberosum</Emphasis> L.)

Tuber shape phenotype is an important determinant of raw product (≥7.6-cm-long French fries) recovery for frozen processing. Tuber length-to-width (L/W) ratios ≥1.8 translate to maximum yield of raw product; however, some cultivars produce tubers with much lower L/W ratios. While gibberellin (GA) can be used to elongate tubers, it also decreases tuber size and can thereby attenuate raw product recovery. We investigated the utility of GA and naphthaleneacetic acid (NAA) combination treatments for modifying tuber set, size, and shape to increase yield of raw product from ‘Payette Russet’ and ‘Alturas’; two late-season frozen-processing cultivars that often produce tubers with undesirably low L/W ratios. Models describing L/W ratio and fry yield by tuber size class were developed to translate total U.S. No. 1 tuber yields (>113 g) into yield of raw product. Increases in the L/W ratios of 113–284-g tubers had a greater effect on recovery of French fries (% fresh wt) than for tubers >284 g. Undersize (<113 g) and oversize (>340 g) tubers yielded 0 and 96% fries, respectively, regardless of L/W ratio. GA applied as a seed treatment effectively hastened emergence and altered tuber shape by increasing the L/W ratios of ‘Alturas’ and ‘Payette Russet’ tubers, enhancing total fry yield for the 113–340-g tubers by 24–46%, depending on concentration and application technique (dip, spray, in-furrow). However, GA also decreased apical dominance and shifted tuber size distribution away from >284-g tubers toward higher yields of <170-g tubers, erasing the gains in fry yield when all size classes (>113 g) were considered. When combined with GA, NAA maintained apical dominance, attenuated the shift in tuber size distribution, had no effect on the GA-induced increase in tuber L/W ratio, and only partly moderated the GA-induced stimulation of plant emergence. Raw product yield from ‘Payette Russet’ increased 12–39% in spray application trials by using NAA to confine the effect of GA to tuber shape and limit the loss of U.S. No. 1 tubers to undersize. Increases in tuber L/W ratio with GA/NAA seed treatments translated to increased yield of fries only when the relative concentrations were adjusted to minimize loss of >284-g tubers and gain in undersize tubers, as dictated by cultivar sensitivity to GA. ‘Alturas’ was less sensitive to GA than ‘Payette Russet’ for shifts in tuber size distribution but not shape, resulting in 17% increase in raw product with GA alone in pre-plant seed spray application studies. GA/NAA combination treatments provide an effective approach to manipulate tuber size distribution and enhance the yield of raw product for frozen processing in cultivars with a rounder tuber shape phenotype.     

Comparison of early life history stages of the bay scallop, Argopecten irradians: Effects of microalgal diets on growth and biochemical composition

The culture of bay scallops, Argopecten irradians, is limited by a reliable and affordable supply of spat and the ability to ensure that animals attain market size within a single growing season. The main goals of our study were thus: (1) to develop growth-optimizing algal diets for implementation in hatcheries, and (2) to identify and compare bay scallop postlarval and juvenile dietary requirements, especially of lipids and fatty acids, which if met may enhance production. Nutritional needs of postlarval bay scallops (present study) are compared with those of sea scallops, Placopecten magellanicus, offered the same diets in a previous companion study. To this end, postlarval (initial shell height, SH = 240 μm) and juvenile (initial SH = 10 mm) bay scallops were offered 6–7 microalgal diet combinations at 20 °C, for 3 weeks. A similar growth ranking among diets was observed between the two developmental stages. A combination diet of Pavlova sp. (CCMP 459) and Chaetoceros muelleri was far superior to any other diet tested, yielding growth rates of 58 and 357 μm day^− 1 which were 65% and 25% higher than the next highest performing diet of Tetraselmis striata/C. muelleri in postlarvae and juveniles, respectively. The T. striata/C. muelleri diet, which is limited in the n-3 fatty acid docosahexaenoic acid (DHA), yielded very poor growth of sea scallop postlarvae in a prior study, indicating that bay scallops may have less stringent requirements for DHA than sea scallops. The Pav 459/C. muelleri diet, which also supported the highest growth of sea scallop postlarvae, is characterized by elevated levels of the n-6 fatty acids, arachidonic (AA) in C. muelleri and 4,7,10,13,16-docosapentaenoic (DPA) in Pav 459. The two diets deficient in AA and n-6 DPA, Pavlova lutheri/Thalassiosira weissflogii and P. lutheri/Fragilaria familica, yielded the lowest growth rates in both bay scallop postlarvae and juveniles. Tissue enrichment of these two fatty acids relative to the diet, as well as overall enrichment in ∑n-6 fatty acids was observed across developmental stages and dietary treatments. A similar pattern has previously been observed in sea scallop postlarvae, suggesting a dietary requirement for n-6 fatty acids in pectinids that has often been overlooked in the past.