The Earth's Magnetic Field: A Simple Measurement of its Strength

Although most teachers agree that a field trip is an important educational experience for their students, many struggle with finding a way to make it connect with their classroom curriculum. Creating an effective field trip involves creating an effective lesson plan and using the resources of the museum, zoo, or aquarium to foster inquiry and learning. By incorporating the learning cycle into their field trip, students are able to use their explorations with animal-based exhibits to develop basic life science concepts.     

Recurrent microbial community types driven by nearshore and seasonal processes in coastal Southern California

A multitude of concurrent biological and physical processes contribute to microbial community turnover, especially in highly dynamic coastal environments. Characterizing what factors contribute most to shifts in microbial community structure and the specific organisms that correlate with changes in the products of photosynthesis improves our understanding of nearshore microbial ecosystem functions. We conducted high frequency sampling in nearshore Southern California in order to capture sub-weekly microbial community dynamics. Microbial communities were characterized by flow cytometry and 16S rRNA gene sequencing, and placed in the context of physicochemical parameters. Within our time-series, season and nutrient availability corresponded to changes in dominant microbial community members. Concurrent aseasonal drivers with overlapping scales of variability were also apparent when we used network analysis to assess the microbial community as subsets of the whole. Our analyses revealed the microbial community as a mosaic, with overlapping groups of taxa that varied on different timescales and correlated with unique abiotic and biotic factors. Specifically, a subnetwork associated with chlorophyll a exhibited rapid turnover, indicating that ecologically important subsets of the microbial community can change on timescales different than and in response to factors other than those that govern turnover of most members of the assemblage.     

Central connections of Limulus ventral photoreceptors revealed by intracellular staining

We stained the central terminations of Limulus ventral photoreceptors by intracellular injection of cobalt chloride into the cell bodies. Axons of these photoreceptors enter the protocerebrum via the ventral optic nerve and pass to the medulla. As they reach the surface of the medullar neuropil they branch profusely in fine processes with intermittent varicosities. Each axonal arborization covers about 0.01-0.02 mm2 of this surface immediately adjacent to the medullar ganglion cell layer. Each point on the surface of the medullar neuropil receives, on the average, input from about 6 ventral photoreceptor axons.     

Genes influencing milk production traits predominantly affect one of four biological pathways

In this study we introduce a method that accounts for false positive and false negative results in attempting to estimate the true proportion of quantitative trait loci that affect two different traits. This method was applied to data from a genome scan that was used to detect QTL for three independent milk production traits, Australian Selection Index (ASI), protein percentage (P%) and fat percentage corrected for protein percentage (F% – P%). These four different scenarios are attributed to four biological pathways: QTL that (1) increase or decrease total mammary gland production (affecting ASI only); (2) increase or decrease lactose synthesis resulting in the volume of milk being changed but without a change in protein or fat yield (affecting P% only); (3) increase or decrease protein synthesis while milk volume remains relatively constant (affecting ASI and P% in the same direction); (4) increase or decrease fat synthesis while the volume of milk remains relatively constant (affecting F% – P% only). The results indicate that of the positions that detected a gene, most affected one trait and not the others, though a small proportion (2.8%) affected ASI and P% in the same direction.