diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
index 50baeb4..1a875d4 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/KmerBytesWritable.java
@@ -358,7 +358,7 @@
      * @param kmer
      *            : the next kmer
      */
-    public void mergeNextKmer(int initialKmerSize, KmerBytesWritable kmer) {
+    public void mergeWithFFKmer(int initialKmerSize, KmerBytesWritable kmer) {
         int preKmerLength = kmerlength;
         int preSize = size;
         this.kmerlength += kmer.kmerlength - initialKmerSize + 1;
@@ -372,8 +372,100 @@
         }
         clearLeadBit();
     }
+    
+    /**
+     * Merge Kmer with the next connected Kmer, when that Kmer needs to be reverse-complemented
+     * e.g. AAGCTAA merge with GGTTGTT, if the initial kmerSize = 3
+     * then it will return AAGCTAACAACC
+     * 
+     * @param initialKmerSize
+     *            : the initial kmerSize
+     * @param kmer
+     *            : the next kmer
+     */
+    public void mergeWithFRKmer(int initialKmerSize, KmerBytesWritable kmer) {
+        int preKmerLength = kmerlength;
+        int preSize = size;
+        this.kmerlength += kmer.kmerlength - initialKmerSize + 1;
+        setSize(KmerUtil.getByteNumFromK(kmerlength));
+        
+        // copy prefix into right-side of buffer
+        for (int i = 1; i <= preSize; i++) {
+            bytes[offset + size - i] = bytes[offset + preSize - i];
+        }
+        
+        // copy complement of suffix in reverse order into left side of buffer.
+        // we read two bits (one letter) at a time from leading bits of kmer, copying their complement 
+        // into my trailing bits
+        byte destByte = 0x00;
+        int destPosn = 0;
+        for (; destPosn < kmer.getKmerLength(); destPosn++) {
+            // srcPosn starts at the end of kmer, but excludes the last (initialKmerSize - 1) letters
+            // there are +1 and -1 terms in there that cancel out :P
+            int srcPosn = kmer.getKmerLength() - destPosn - initialKmerSize;
+            byte compLetter = GeneCode.getPairedCodeFromSymbol(kmer.getGeneCodeAtPosition(srcPosn));
+            if ((destPosn % 4) == 0 && destPosn >= 4) {
+                // byte is full.  write the complete byte to storage
+                bytes[offset + preSize - (destPosn / 4)] = destByte;
+                destByte &= 0x00;
+            }
+            destByte = (byte) ((destByte << 2) | compLetter);
+        }
+        // fill in the leading, partial byte
+        bytes[offset + preSize - (destPosn / 4)] = destByte;
+        clearLeadBit();
+    }
 
     /**
+     * Merge Kmer with the previous connected Kmer, when that kmer needs to be reverse-complemented
+     * e.g. AACAACC merge with TTCTGCC, if the initial kmerSize = 3
+     * then it will return GGCAGAACAACC
+     * 
+     * @param initialKmerSize
+     *            : the initial kmerSize
+     * @param preKmer
+     *            : the previous kmer
+     */
+    public void mergeWithRFKmer(int initialKmerSize, KmerBytesWritable preKmer) {
+        int preKmerLength = kmerlength;
+        int preSize = size;
+        this.kmerlength += preKmer.kmerlength - initialKmerSize + 1;
+        setSize(KmerUtil.getByteNumFromK(kmerlength));
+        byte cacheByte = getOneByteFromKmerAtPosition(0, bytes, offset, preSize);
+        
+        // copy reverse complement of prekmer
+        // copy complement of suffix in reverse order into left side of buffer.
+        // we read two bits (one letter) at a time from leading bits of kmer, copying their complement 
+        // into my trailing bits
+        byte destByte = 0x00;
+        int destPosn = 0;
+        for (; destPosn < preKmer.getKmerLength(); destPosn++) {
+            // srcPosn starts at the end of kmer
+            int srcPosn = preKmer.getKmerLength() - destPosn - 1;
+            byte compLetter = GeneCode.getPairedCodeFromSymbol(preKmer.getGeneCodeAtPosition(srcPosn));
+            if ((destPosn % 4) == 0 && destPosn >= 4) {
+                // byte is full.  write the complete byte to storage
+                bytes[offset + size - (destPosn / 4)] = destByte;
+                destByte &= 0x00;
+            }
+            destByte = (byte) ((destByte << 2) | compLetter);
+        }
+        // fill in the leading, partial byte
+        bytes[offset + preSize - (destPosn / 4)] = destByte;
+        
+        // copy current kmer
+        int k = 4;
+        for (; k < preKmerLength; k += 4) {
+            byte onebyte = getOneByteFromKmerAtPosition(k, bytes, offset, preSize);
+            appendOneByteAtPosition(preKmer.kmerlength - initialKmerSize + k - 4 + 1, cacheByte, bytes, offset, size);
+            cacheByte = onebyte;
+        }
+        appendOneByteAtPosition(preKmer.kmerlength - initialKmerSize + k - 4 + 1, cacheByte, bytes, offset, size);
+        clearLeadBit();
+    }
+    
+    
+    /**
      * Merge Kmer with the previous connected Kmer
      * e.g. AACAACC merge with AAGCTAA, if the initial kmerSize = 3
      * then it will return AAGCTAACAACC
@@ -383,7 +475,7 @@
      * @param preKmer
      *            : the previous kmer
      */
-    public void mergePreKmer(int initialKmerSize, KmerBytesWritable preKmer) {
+    public void mergeWithRRKmer(int initialKmerSize, KmerBytesWritable preKmer) {
         int preKmerLength = kmerlength;
         int preSize = size;
         this.kmerlength += preKmer.kmerlength - initialKmerSize + 1;
@@ -417,7 +509,7 @@
 
         buffer[position] = (byte) ((buffer[position] & mask) | ((0xff & onebyte) << shift));
         if (position > start && shift != 0) {
-            buffer[position - 1] = (byte) ((buffer[position - 1] & (0xff - mask)) | ((byte) ((0xff & onebyte) >> (8 - shift))));
+            buffer[position - 1] = (byte) ((buffer[position - 1] & (0xff - mask)) | ((byte) ((0xff & onebyte) >>> (8 - shift))));
         }
     }
 
@@ -427,7 +519,7 @@
             throw new IllegalArgumentException("Buffer of kmer storage is invalid");
         }
         int shift = (k % 4) << 1;
-        byte data = (byte) (((0xff) & buffer[position]) >> shift);
+        byte data = (byte) (((0xff) & buffer[position]) >>> shift);
         if (shift != 0 && position > start) {
             data |= 0xff & (buffer[position - 1] << (8 - shift));
         }
diff --git a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/NodeWritable.java b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/NodeWritable.java
index 8955aab..8aab267 100644
--- a/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/NodeWritable.java
+++ b/genomix/genomix-data/src/main/java/edu/uci/ics/genomix/type/NodeWritable.java
@@ -121,13 +121,13 @@
     public void mergeForwardNext(NodeWritable nextNode, int initialKmerSize) {
         this.forwardForwardList.set(nextNode.forwardForwardList);
         this.forwardReverseList.set(nextNode.forwardReverseList);
-        kmer.mergeNextKmer(initialKmerSize, nextNode.getKmer());
+        kmer.mergeWithFFKmer(initialKmerSize, nextNode.getKmer());
     }
 
     public void mergeForwardPre(NodeWritable preNode, int initialKmerSize) {
         this.reverseForwardList.set(preNode.reverseForwardList);
         this.reverseReverseList.set(preNode.reverseReverseList);
-        kmer.mergePreKmer(initialKmerSize, preNode.getKmer());
+        kmer.mergeWithRRKmer(initialKmerSize, preNode.getKmer());
     }
 
     public void set(NodeWritable node) {
diff --git a/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/data/test/KmerBytesWritableTest.java b/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/data/test/KmerBytesWritableTest.java
index 5a59a87..8438a44 100644
--- a/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/data/test/KmerBytesWritableTest.java
+++ b/genomix/genomix-data/src/test/java/edu/uci/ics/genomix/data/test/KmerBytesWritableTest.java
@@ -127,12 +127,12 @@
         Assert.assertEquals(text2, kmer2.toString());
         KmerBytesWritable merge = new KmerBytesWritable(kmer1);
         int kmerSize = 8;
-        merge.mergeNextKmer(kmerSize, kmer2);
+        merge.mergeWithFFKmer(kmerSize, kmer2);
         Assert.assertEquals(text1 + text2.substring(kmerSize - 1), merge.toString());
 
         for (int i = 1; i < 8; i++) {
             merge.set(kmer1);
-            merge.mergeNextKmer(i, kmer2);
+            merge.mergeWithFFKmer(i, kmer2);
             Assert.assertEquals(text1 + text2.substring(i - 1), merge.toString());
         }
 
@@ -148,7 +148,7 @@
                 Assert.assertEquals(text2, kmer2.toString());
                 for (int x = 1; x < jk; x++) {
                     merge.set(kmer1);
-                    merge.mergeNextKmer(x, kmer2);
+                    merge.mergeWithFFKmer(x, kmer2);
                     Assert.assertEquals(text1 + text2.substring(x - 1), merge.toString());
                 }
             }
@@ -168,12 +168,12 @@
         Assert.assertEquals(text2, kmer2.toString());
         KmerBytesWritable merge = new KmerBytesWritable(kmer2);
         int kmerSize = 8;
-        merge.mergePreKmer(kmerSize, kmer1);
+        merge.mergeWithRRKmer(kmerSize, kmer1);
         Assert.assertEquals(text1 + text2.substring(kmerSize - 1), merge.toString());
 
         for (int i = 1; i < 8; i++) {
             merge.set(kmer2);
-            merge.mergePreKmer(i, kmer1);
+            merge.mergeWithRRKmer(i, kmer1);
             Assert.assertEquals(text1.substring(0, text1.length() - i + 1) + text2, merge.toString());
         }
 
@@ -189,7 +189,7 @@
                 Assert.assertEquals(text2, kmer2.toString());
                 for (int x = 1; x < ik; x++) {
                     merge.set(kmer2);
-                    merge.mergePreKmer(x, kmer1);
+                    merge.mergeWithRRKmer(x, kmer1);
                     Assert.assertEquals(text1.substring(0, text1.length() - x + 1) + text2, merge.toString());
                 }
             }